EXAMINATION 1 Chemistry 3B. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B:

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1 1 EXAMINATIN 1 Chemistry 3B Name: Print first name before second! Use capital letters! SID #: Peter Vollhardt February 23, 2006 Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 17 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. (30) II. (30) III. (50) IV. (50) V. (40) VI. (30) VII. (20) Total: (250)

2 2 I. [30 Points] Name or draw, as appropriate, the following molecules according to the IUPAC rules. Indicate stereochemistry where necessary (cis, trans, R, or S). a. C I Br b. c. R-4-Methyl-2-cyclohexenone d. Meta-(1-methylethyl)(methoxymethyl)benzene

3 3 e. II. [30 Points] 1-Methylthio-4-nitrobenzene A undergoes preferential electrophilic attack by E + to give only one of the two products shown. SC 3 SC 3 SC E E or E N 2 A N 2 N 2 a. Which one? Mark the box below your choice with an X. b. Write the resonance forms of the intermediate formed on attack of E + at: C-2: Four resonance forms

4 4 C-3: Three resonance forms c. Circle (in your answers above): a. the most strongly contributing resonance form of the attack at C-2 and b. the least contributing resonance form of the attack at C-3. III. [50 Points] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Aqueous work-up (when required) is assumed to be part of a step. It is not part of any answer. a. + Cl Thermodynamic product b. Δ 3 C C 3 3 C C 3 A cyclobutene

5 5 c. CN + CN d. hν A hexatriene isomer of product. e. C 3 C 3 K + - C(C 3 ) 3 13 C NMR: 7 lines A salt; 13 C NMR: 4 lines f. Cl S 3, 2 S 4 C 3 N 2

6 6 g. + C 3 CC C NMR: 4 lines h. 1. Cl, AlCl 3 2. Zn(g), Cl, Δ i. 1. P(C 6 5 ) 3 2. C 3 Li 3. I

7 7 j. 2 NN 2, Δ, and IR Spectrum of product : A hydrocarbon cm -1 IV. [50 Points] Treatment of acetal A with conc. nitric acid and 2 S 4 led to unknown B. The IR and NMR spectra of this product are shown below. 1. N 3, 2 S , +, Δ B (unknown) 3 S A

8 8 a. After consideration of the spectral data, write the structure of the product in the box below. Structure of unknown b. Interpret the spectral data as requested in the spaces provided. 1. IR Spectrum Confirm or rule out the presence or absence (circle one) of the following bonds. Enter an approximate expected stretching frequency in the box. ~ ν 2 (Csp ) is: present absent at cm -1

9 9 ~ ν ( ) is: present absent at cm -1 ~ ν (C=) is: present absent at cm C NMR Spectrum (these are all single lines; ignore the seeming splitting of some). A D B C ppm The proton-coupled spectrum leaves the singlets for B, C, and D unchanged.

10 10 Draw your suggestion for the unknown in the box below and label the types of carbon atoms A, B, C, and D, giving rise to the corresponding signals in the spectrum. For the assignment of B, C, and D, consider that the order of chemical shifts parallels roughly the order of electronegativity of the attached atom NMR Spectrum (for expanded sections, see next two pages). A B C D E ppm

11 11 The signal due to protons A disappears in D 2 solvent. B A ppm C

12 12 ppm D E ppm Draw your suggestion for the unknown in the box and label the hydrogens A, B, C, D, and E giving rise to the corresponding signals in the spectrum.

13 13 V. [40 Points] Write detailed step-wise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! Work from left to right in the following spaces. There is much more space than you will need. a. N 2 N + +

14 14 b. C 3 CC 3 + C 3 C + C 3 CC 3 + C 3 C Work from left to right in the following spaces. There is much more space than you will need.

15 15 VI. [30 Points] Provide a reasonable synthetic route from starting material to product. Note: Several steps are required, and there may be more than one solution to the problem. Do not write mechanisms! a. ere, you may use any additional organic or organometallic reagents to effect your conversions. Work from left to right in the following spaces. There is much more space than you will need.

16 16 b. Synthesize compound A using only the materials shown and no additional reagents. N,, 2 NN 2 N A Work from left to right in the following spaces. There is much more space than you will need.

17 17 VII. [20 Points] Place an X mark in the box next to the most accurate statement. a. The equilibrium constant for hydration of 1, 2, and 3 increases in the order F 3 C 3 C C 3 C 3 C , 2, 3 3, 2, 1 2, 3, 1 3, 1, 2 b. Circle the compounds which are aromatic : The End

18 1 EXAMINATIN 1 Chemistry 3B Name: Print first name before second! Use capital letters! SID #: Peter Vollhardt September 28, 2006 Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 20 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. (30) II. (30) III. (50) IV. (60) V. (30) VI. (30) VII. (20) Total: (250)

19 I. [30 Points] Name or draw, as appropriate, the following molecules according to the IUPAC rules. Indicate stereochemistry where necessary (cis, trans, R, or S). 2 a. Br Cl b. F c. S-4-Methyl-2-cyclohexenone d. 4-Methyl-3-nitrobenzenecarbaldehyde

20 3 e. II. [30 Points] Compound A undergoes preferential electrophilic attack by E + to give only one of the two products shown. C 3 C 3 C 3 2 N N 2 5 A E N N 2 2 N N 2 or E E a. Which one? Mark the box below your choice with an X. b. Write the resonance forms of the intermediate formed on attack of E + at: C-4: Three resonance forms

21 4 C-5: Three resonance forms c. Circle (in your answers above): a. the most strongly contributing resonance form of the attack at C-4 and b. the most strongly contributing resonance form of the attack at C-5. III. [50 Points] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Aqueous work-up (when required) is assumed to be part of a step. It is not part of any answer. a. C 3 S Solvolysis Thermodynamic product b. C(C 3 ) 3 hν C(C 3 ) 3

22 5 c. + d. Δ C 3 C 3 An octatetraene isomer of product. e. RR + NBr + N

23 6 f. N C 3 S3, 2S4 F g. +, C 3 IR spectrum of product :

24 7 h. C 3 Br 2, FeBr 3 C 3 Monobromination i S 3 3. N 2

25 8 j. 1. S S 2. Mass spectrum of product :

26 9 IV. [60 Points] eating compound A with acetylene gas under pressure generated the unknown B. The complete spectral data for this product are shown below in the sequence : 1. 1 NMR, C NMR, 3. Mass, 4. IR, 5. UV. C 3 Δ + C C B (unknown) Cl C 3 A a. After consideration of the spectral data, write the structure of the product in the box below.

27 NMR Spectrum (for expanded section, see bottom spectrum). C A B ppm 9 z A B ppm

28 b. Draw again your suggestion for the unknown in the box and label the hydrogens A, B, and C giving rise to the corresponding signals in the spectrum. Consider resonance in your assignments of A and B C NMR Spectrum (these are five single lines). C D E A B ppm

29 12 The proton-coupled 13 C NMR spectrum leaves the singlets for A and B unchanged, but shows that each of the carbons giving rise to signals C and D are attached to one hydrogen, while the carbon due to E bears three hydrogens. Draw again your suggestion for the unknown in the box below and label the types of carbon atoms A E giving rise to the corresponding signals in the spectrum. For the assignments of A versus B and C versus D, consider the effect of electronegativity of the attached atom and the effect of resonance, respectively.

30 13 3. Mass spectrum a. Clearly mark on the spectrum the molecular ion as M +. b. In the box above the fragment ion m/z = 199, indicate the molecular piece that has fragmented from M +, e.g. Cl, or C 3, or C 3 C 2, or?

31 14 4. IR Spectrum Confirm or rule out the presence or absence (circle one) of the following bonds. Enter an approximate expected stretching frequency in the box. ~ ν 2 (Csp ) is: present absent at cm 1 ~ ν (Csp ) is: present absent at cm 1 ~ ν (C C) is: present absent at cm 1

32 15 5. UV spectrum nm Place an X mark into the box next to the most accurate statement. The spectrum depicts a nonconjugated compound. The spectrum is that of a colored compound. The unknown is aromatic. The λ max is at 300 nm.

33 16 V. [30 Points] Write detailed step-wise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! Work from left to right in the following spaces. There is much more space than you will need. a. Catalytic +

34 17 b. Cl 3 CC Cl 3 C C Work from left to right in the following spaces. There is much more space than you will need.

35 18 VI. 30 Points] Provide a reasonable synthetic route from starting material to product. Note: Several steps are required, and there may be more than one solution to the problem. Do not write mechanisms! a. C 3 C 3 3 C C 3 3 C C 3 N 2 Work from left to right in the following spaces. There is much more space than you will need.

36 19 b. Synthesize compound A from any materials containing six carbons or less. C 3 C 2 C 3 A Work from left to right in the following spaces. There is much more space than you will need.

37 20 VII. [20 Points] Place an X mark in the box next to the most accurate statement. a. The electron donating power of benzene substituents 1 4 increases in the order C 3 N C 3 C 3 C 3 N , 2, 3, 4 4, 3, 2, 1 4, 2, 3, 1 4, 1, 2, 3 b. Circle the compounds which are aromatic : : The End

38 1 EXAMINATIN 1 Chemistry 3B Name: Print first name before second! Use capital letters! SID #: Peter Vollhardt ctober 2, 2008 GSI (if you are taking Chem 3BL): Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 20 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. (30) II. (30) III. (50) IV. (60) V. (30) VI. (30) VII. (20) Total: (250)

39 I. [30 Points] Name or draw, as appropriate, the following molecules according to the IUPAC rules. Indicate stereochemistry where necessary (cis, trans, R, or S). 2 a. Br b. c. (S)-3-Methylcyclohexanone d. trans-4-bromo-2-oxo-3-butenal

40 3 e. II. [30 Points] Compound A undergoes preferential electrophilic attack by E + to give only one of the three products shown. C 3 C 3 C 3 C N 2 E + N or E E N 2 or E N 2 C 3 C 3 C 3 C 3 A a. Which one? Mark the box below your choice with an X. b. Write the resonance forms of the intermediate formed on attack of E + on A at: C-3: Three resonance forms

41 4 C-5: Three resonance forms C-6: Four resonance forms c. Circle (in your answers above) the most strongly contributing resonance forms of the attack at C-3, C-5, and C-6. d. Considering all of the above most strongly contributing resonance forms, which one is the best overall? Redraw it in the box below.

42 5 III. [50 Points] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Show stereochemistry when appropriate. Aqueous work-up (when required) is assumed to be part of a step. It is not part of any answer. a. S C 3 (solvent) Thermodynamic product b. C 3 hν C 3 c. +

43 6 d. C 3 Δ C 3 Product of ring opening e. hυ + NBr + N f. N C 3 S3, 2S4 F

44 7 g. +, C 2 C 2 IR spectrum of product: h. C 3 Br 2, FeBr 3 Cl Monobromination

45 8 i S 3 3. N 2 C 3 C 3 j

46 9 IV. [60 Points] An attempt to effect allylic bromination of A generated the unknown B. The complete spectral data for this product are shown below in the sequence: 1. 1 NMR, C NMR, 3. Mass, 4. IR, 5. UV. + NBr B (Unknown) 3 C A a. After consideration of the spectral data, write the structure of the product in the box below.

47 NMR Spectrum (for expanded section, see bottom spectrum). A B C D B C ppm

48 b. Draw again your suggestion for the unknown in the box and label the hydrogens A, B, C and D giving rise to the corresponding signals in the 1 NMR spectrum on p. 10. Consider resonance in your assignments of B and C C NMR Spectrum (these are six single lines). E C F A B D ppm

49 12 DEPT spectra (don t worry if you don t remember what that is) shows that the carbons giving rise to signals A, C, and E are attached to one hydrogen each. Signal F is due to a carbon with 3 attached hydrogens. Signals B and D are associated with carbons without any bound hydrogens. Draw again your suggestion for the unknown in the box below and label the types of carbon atoms A F giving rise to the corresponding signals in the 13 C NMR spectrum on p. 11. For the assignments of B versus D and C versus E, consider the effect of electronegativity of the attached atom and the effect of resonance, respectively.

50 3. Mass spectrum Atomic weights of all the elements in the reaction on p. 9: 1; C 12; N 14; 16, Br 79 and 81 (1:1 isotope ratio). Caution: Not all of these elements are incorporated in the product a. Clearly mark on the spectrum the molecular ion as M + and the base peak as B +. b. In the box above the fragment ion m/z = 135, indicate the structure of this fragment.

51 14 4. IR Spectrum Confirm the presence or absence (circle one) of the following bonds. Enter an approximate expected stretching frequency in the box. ~ ν 2 (Csp ) is: present absent at cm 1 ~ ν 3 (Csp ) is: present absent at cm 1 ~ ν (C=) is: present absent at cm 1

52 15 5. UV spectrum nm Place an X mark into the box next to the most accurate statement. The spectrum depicts a nonconjugated compound. The spectrum is that of a colored compound. The unknown is aromatic. The λ max is at 300 nm.

53 V. [30 Points] Write detailed stepwise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! Work from left to right in the following spaces. There is much more space than you will need. 16 a. N 2 Catalytic + N

54 17 b. Work from left to right in the following spaces. There is much more space than you will need.

55 VI. [30 Points] Provide a reasonable synthetic route from starting material to product. Note: Several steps are required, and there may be more than one solution to the problem. Do not write mechanisms! Write out each step separately, including reagents and products. 18 a. C 2 Caution: You cannot introduce the C 2 group directly. int: To do so, think alcohol synthesis. Work from left to right in the following spaces. There is much more space than you will need.

56 b. Synthesize compound A from any acyclic materials containing six carbons or less. int: Think Diels-Alder reaction. Caution: Work backwards. What compound must precede A for a retro-diels-alder step? 19 CN CN A Work from left to right in the following spaces. There is much more space than you will need.

57 20 VII. [20 Points] Place an X mark in the box next to the most accurate statement. a. The electron withdrawing power of benzene substituents 1 4 decreases and their electron donating power increases in the order C 3 C 3 F N , 2, 3, 4 4, 3, 1, 2 4, 2, 3, 1 4, 1, 2, 3 b. Circle the compounds which are aromatic : : The End

58 1 EXAMINATIN 1 Chemistry 3B Name: Print first name before second! Use capital letters! SID #: Peter Vollhardt ctober 1, 2009 GSI (if you are taking Chem 3BL): Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 15 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. (30) II. (30) III. (50) IV. (40) V. (40) VI. (40) VII. (20) Total: (250)

59 2 I. [30 Points] Name or draw, as appropriate, the following molecules according to the IUPAC rules. Indicate stereochemistry where necessary (cis, trans, E, Z, R, or S). a. b. c. (R)-2-Methylcyclohexanone d. (E)-3-(p-Methylphenyl)but-2-en-1-ol

60 3 e. II. [30 Points] Compound A undergoes preferential electrophilic nitration to give only one product CF 3 CF 3 CF 3 2 N CF 3 N 3, 2 S 4 or or N 2 2 N C 3 C 3 C 3 C 3 A a. Which one? Mark the box below your choice with an X, preferably after you have completed questions b. d. b. Write all the resonance forms of the intermediate formed by attack of E + (= N 2 + ) on A at: C-3: CF C 3 Note: A first stencil is provided for format. Leave out the numbering in any additional structures.

61 4 C-5: CF C 3 Note: A first stencil is provided for format. Leave out the numbering in any additional structures CF C-6: C 3 Note: A first stencil is provided for format. Leave out the numbering in any additional structures. c. Circle (in your answers above) the most strongly contributing resonance forms of the attack at C-3, C-5, and C-6. d. Considering all of the above most strongly contributing resonance forms, which one is the best overall? Redraw it in the box below CF C 3

62 5 III. [50 Points] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Show stereochemistry when appropriate. Aqueous work-up (when required) is assumed to be part of a step. It is not part of any answer. a. b. C 3, + c. C 3 CN C 3 + C 3 CN Use the stencil above and add all the groups missing from the hashed and wedged bonds.

63 6 d. C 3 Δ C 3 Product of ring opening e. f. C 3 3 C S 3, 2 S 4 2 N F

64 7 g. h. C 3 Br 2, FeBr 3 Cl Monobromination i

65 8 j. C 3 C 3 C 3 C 3 Two diastereomers. Add the missing pieces. IV. [40 Points] a. In the reaction shown, which product is the result of 1,4-addition, and which is the thermodynamic product, respectively? Circle the appropriate answer. 3 C Cl Cl 3 C + 3 C Cl A B Product of 1,4-addition: A B Thermodynamic product: A B

66 9 b. Rank compounds 1 5 in order of increasing acidity. Mark the box next to the best answer below. 1, 2, 3, 4, 5 1, 4, 2, 3, 5 3, 1, 5, 4, 2 5, 3, 1, 4, 2 4, 1, 2, 5, 3 c. Circle the compounds which are aromatic: C 3 C 3

67 10 d. Rank compounds 1 5 in order of increasing reactivity as dienes in the Diels-Alder reaction: 1, 2, 3, 4, 5 1, 4, 2, 3, 5 3, 1, 5, 4, 2 5, 3, 1, 4, 2 3, 1, 2, 4, 5

68 11 V. [40 Points] Write detailed stepwise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! a. Work from left to right in the following spaces. There is much more space than you will need.

69 b. Intramolecular Friedel-Crafts alkylation of A provided the expected B, but also 10% of C, suggesting the operation of a competing pathway to the normal mechanism. Propose such a pathway to C. Caution: Do not propose a pathway to B, it will not be graded! int: While unusual in this case, what is the normally preferred position of electrophilic attack in naphthalene? 12 Work from left to right in the following spaces. There is much more space than you will need.

70 VI. [40 Points] Provide a reasonable synthetic route from starting material to product. Note: Several steps are required, and there may be more than one solution to the problem. Do not write mechanisms! Write out each step separately, including reagents and products. 13 a. Work from left to right in the following spaces. There is much more space than you will need.

71 14 b. Synthesize compound A from any acyclic materials and any other reagent. int: Think Diels-Alder reaction. Caution: Work backwards. A (racemate) Work from left to right in the following spaces. There is much more space than you will need.

72 15 VII. [20 Points] Place an X mark in the box next to the most accurate statement. a. Kinetic versus thermodynamic control is present when a racemate is formed in a reaction the (4N+2) rule overrides the Lewis octet rule of two isomeric products the less stable one is formed the reaction requires heat to go to completion everything happens all at once b. The reactivity of the carbonyl group increases with increasing electrophilic character of the carbonyl carbon with electron donating substituents on formation of acetals on reduction on going from aldehydes to ketones The End

73 1 EXAMINATIN 2 Chemistry 3B Name: Print first name before second! Use capital letters! SID #: Laboratory GSI (if applicable): Peter Vollhardt April 6, 2006 Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 18 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. (20) II. (50) III. (60) IV. (40) V. (60) VI. (20) Total: (250)

74 2 I. [20 Points] Write a detailed mechanism of the following aldol condensation using arrow pushing techniques. Na, 2 C 3 +

75 ~ ν 3 II. a. [50 Points] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Aqueous work-up (when required) is assumed to be part of a step. It is not part of any answer. 2, + IR: = 3350 (broad), 1720 cm 1 b. 1. SCl 2 2. C 3 C 3 Mass spectrum of starting material:

76 4 c. Cl d. Na, Br 2 N 2 e C f. N 2 N 3, NaB 3 CN 13 C NMR : δ = 208.9, 45.7, 29.8, 17.4, 13.7 ppm

77 5 g. N N N C 3 C 3 h. 3 C C 3 3 C C 3 i. + +, TF N IR: No peaks >3010 cm 1 j. + 2 C 3 MgBr

78 6 III. [60 Points] Subjecting acid A to the three step sequence shown below led to unknown B. The mass, IR, and NMR spectra of this product are shown on the following pages. 1. PBr 3 2. Br 2 3. N 3 (excess) B (unknown) A a. After consideration of the spectral data, write the structure of the product in the box below. Structure of unknown b. Interpret the spectral data as requested in the spaces provided, starting on the following page.

79 7 1. Mass Spectrum Label the molecular ion as M + and the base peak as BP. Using the partial periodic table on the previous page for atomic weights, draw the structures of the fragment ions at m/z = 148, 120, 91, and 77, respectively, in the boxes below. Draw a + charge at the point of the dangling valence in your line structure. m/z = 148 m/z = 120 m/z = 91 m/z = 77

80 8 2. IR Spectrum Confirm or rule out the presence or absence (circle one) of the following bonds. Enter an approximate expected stretching frequency in the box. ~ ν 3 (Csp ) is: present absent at cm 1 ~ ν 2 (Csp ) is: present absent at cm 1 ~ ν (N ) is: present absent at cm 1 ~ ν (C=) is: present absent at cm 1

81 C NMR Spectrum (these are all single lines; ignore the seeming splitting of some). B C D A ppm Draw your suggestion for the unknown in the box below and label the types of carbon atoms A, B, C, and D, giving rise to the corresponding signals in the spectrum. Note that B is a group of four signals, which belong to a group of similar carbon atoms all of which should be labeled B.

82 NMR Spectrum (for expanded sections, see below and the next page). A,B D E F G C ppm B A C ppm

83 11 As indicated on the spectra, the signals due to protons A, C, and G disappear in D 2 solvent ( exchanges ). ppm Draw your suggestion for the unknown in the box and label the hydrogens A G giving rise to the corresponding signals in the spectrum. Note: A and C can be assigned arbitrarily. B corresponds to a group of five hydrogens that can be assigned as such. E and F are due to hydrogens attached to the same carbon and can also be assigned arbitrarily.

84 12 IV. [40 Points] Write detailed step-wise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! Work from left to right in the following spaces. There is much more space than you will need. a. N C 2, Pd C, Δ N Note: Disregard the mechanism of catalytic hydrogenation.

85 13 b. + Cl 2 Cl Cl Work from left to right in the following spaces. There is much more space than you will need.

86 V. [60 Points] Provide a reasonable synthetic route from starting materials to product. Note: Several steps are required, and there may be more than one solution to the problem. You may use any additional organic or organometallic reagents to effect your conversions. Do not write mechanisms! 14 a. 2 N C 3 Work from left to right in the following spaces. There is much more space than you will need.

87 15 b. Na +- CN In 3 steps or less Work from left to right in the following spaces. There is much more space than you will need.

88 16 c. P(C 6 5 ) 3 Br Work from left to right in the following spaces. There is much more space than you will need.

89 17 VI. [20 Points] a. Name the following molecule according to the IUPAC rules. N C 3 b. The mass spectrum of 2-propylcyclohexanone is shown below. What is the origin of the large fragmentation peak at m/z = 98? Show your answer in the form of a scheme using e- pushing.

90 The End 18

91 EXAMINATIN 2 Chemistry 3B Name: Print first name before second! Use capital letters! Peter Vollhardt November 2, 2006 SID #: Laboratory GSI (if applicable): Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 21 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. (25) II. (50) III. (50) IV. (45) V. (45) VI. (35) Total: (250)

92 Chemistry 3B, Examination 2 Page 2 I. [25 Points] Write the products of the following reactions of the starting material, methyl 3- methylbutanoate. C 3 C 2, + C 3 N 2, Δ 1. C 3 MgBr (2 equiv.) 2. +, 2 work-up C 3 1. LiAl , 2 work-up 1. Al 2. +, 2 work-up 2

93 Chemistry 3B, Examination 2 Page 3 II. [50 Points] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Aqueous work-up (when required) is assumed to follow each step. It is not part of any answer. a. N, + Mass spectrum of product::

94 Chemistry 3B, Examination 2 Page 4 b. 1. CN 2. +, 2 C 13 C Spectrum of starting material: c.

95 Chemistry 3B, Examination 2 Page 5 d. C 3 C e. C 3 Na, 2, Δ C f. C Br C

96 Chemistry 3B, Examination 2 Page 6 g. C 3 +, C 3 C IR spectrum of product : h. CN C 2 N 2

97 Chemistry 3B, Examination 2 Page 7 i. Cl 2, Na N 2 IR spectrum of starting material : j. C 3 N

98 Chemistry 3B, Examination 2 Page 8 III. [50 Points] Treatment of 2-bromopropanoic acid A with base gave, after work-up with aqueous Br, mainly 2-propenoic acid, but, in addition, a small amount of a side product B. The spectral data for this product are shown below in the sequence : 1. 1 NMR, C NMR, 3. Mass, 4. IR. Br 1. Na 2. Br, 2 + B (unknown) A 2-Propenoic acid a. After consideration of the spectral data, write the structure of the product in the box below.

99 Chemistry 3B, Examination 2 Page NMR Spectrum (for expanded section, see bottom spectrum).

100 Chemistry 3B, Examination 2 Page 10 b. Draw again your suggestion for the unknown in the box and label the hydrogens A, B, and C giving rise to the corresponding signals in the spectrum. Use the Table below, if necessary.

101 Chemistry 3B, Examination 2 Page C NMR Spectrum. Draw again your suggestion for the unknown in the box below and label the types of carbon atoms A C giving rise to the corresponding signals in the spectrum. int: The carbon giving rise to the signal labeled B above is attached to the hydrogens giving rise to signal B in the 1 NMR spectrum. Similarly, the carbon giving rise to the signal labeled C above is attached to the hydrogens giving rise to signal C in the 1 NMR spectrum.

102 Chemistry 3B, Examination 2 Page Mass spectrum. int: Atomic weights: C = 12; = 1; = 16; Br exists in nature as a 1:1 mixture of Br = 79 and Br = 81. a. Clearly mark on the spectrum the molecular ion(s) as M +. b. In the boxes above the respective fragment ions, indicate the molecular piece that has fragmented from M +, e.g. Cl, or C 3, or C 3 C 2, or?

103 Chemistry 3B, Examination 2 Page IR Spectrum. Confirm or rule out the presence or absence (circle one) of the following bonds. Enter an approximate expected stretching frequency in the box. ~ ν 2 (Csp ) is: present absent at cm 1 ~ ν 3 (Csp ) is: present absent at cm 1 ~ ν ( ) is: present absent at cm 1 ~ ν (C=) is: present absent at cm 1

104 Chemistry 3B, Examination 2 Page 14 IV. [45 Points] Write detailed step-wise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! a. Catalytic + Work from left to right in the following spaces. There is more space than you will need.

105 Chemistry 3B, Examination 2 Page 15 b Work from left to right in the following spaces. There is more space than you will need.

106 Chemistry 3B, Examination 2 Page 16 c. Na, 2, Δ (Don t worry about stereochemistry). Work from left to right in the following spaces. int: Work backwards to unravel the product!

107 Chemistry 3B, Examination 2 Page 17 V. [45 Points] Provide a reasonable synthetic route from starting material to product. Note: Several steps are required, and there may be more than one solution to the problem. Do not write mechanisms! a. + any other material N Work from left to right in the following spaces. There is more space than you will need.

108 Chemistry 3B, Examination 2 Page 18 b. Synthesize (racemic) compound A from 2-butanone and any materials containing four carbons or less. A Work from left to right in the following spaces. There is more space than you will need.

109 Chemistry 3B, Examination 2 Page 19 c. ne step in this sequence will not work. Circle the reaction arrow denoting this step. Note: Appropriate aqueous work-up (when required) follows each step and is not indicated. + cat. LiAl 4 Mn 2 CC 3 Cr 3, 2 2, Pd C C (C 3 C 2 ) 2 CuLi Na, 2, Δ VI. [35 Points] Place an X mark in the box next to the most accurate statement. a. The reactivity of 1 4 toward N 3 increases in the order C3CCl C 3 CN 2 C 3 CC 3 C 3 CCC , 2, 3, 4 4, 3, 2, 1 2, 3, 4, 1 3, 2, 1, 4

110 Chemistry 3B, Examination 2 Page 20 b. The acidity of 1 4 increases in the order + N 4 C 3 CC 3 C 3 CC 3 C , 2, 3, 4 4, 3, 2, 1 2, 3, 4, 1 3, 2, 1, 4 c. A researcher finds two unlabeled bottles containing liquids in a cabinet. e knows that one of them is azacyclohexane A, the other is the ether analog B. A 13 C NMR spectrum of the contents of bottle 1 shows δ = 25.5, 27.2, and 47.5 ppm, while that of bottle 2 shows δ = 23.6, 26.6, and 68.0 ppm. What is in bottle 1, A or B? Bottle 1 contains N A Bottle 1 contains B

111 Chemistry 3B, Examination 2 Page 21 d. In problem c., give one (and only one) other spectral technique that would solve it and why or how. Place your respective answers into the boxes below. ther spectral technique ow will this technique distinguish between A and B? (ne sentence or expression only!) "A little knowledge is a dangerous thing. But, then, so is a lot." A. Einstein The End

112 EXAMINATIN 2 Chemistry 3B Name: Print first name before second! Use capital letters! Peter Vollhardt November 4, 2008 SID #: Laboratory GSI (if applicable): Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 20 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. (25) II. (50) III. (50) IV. (45) V. (45) VI. (35) Total: (250)

113 Chemistry 3B, Examination 2 Page 2 I. [25 Points] Write the organic products of the following reactions of the starting amide. 2 S 4, 2 N : Li : (LDA) 1. Al 2. +, 2 work-up N 2 1. LiAl , 2 work-up Cl 2, Na

114 Chemistry 3B, Examination 2 Page 3 II. [50 Points] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Aqueous work-up (when required) is assumed to follow each step. It is not part of any answer. a. D 2, NaD Mass spectrum of product: m/z = 102 b. 1. CN 2. +, 2, Δ 13 C Spectrum of product:

115 Chemistry 3B, Examination 2 Page 4 c. d. C 3 C e. 3 C C 3 Na, 2, Δ C 6 8

116 Chemistry 3B, Examination 2 Page 5 f. C C Cl g. Cl C 3 h. MgBr 2 equiv. C 3

117 Chemistry 3B, Examination 2 Page 6 i. + Cl, C 3 C 2 (solvent) N Two additional neutral reagents Product after basic work-up j. 3 C Two reagents N C 3

118 Chemistry 3B, Examination 2 Page 7 III. [50 Points] In an attempt to hydrolyze lactone A with concentrated aqueous Br, a student obtained compound B. The complete spectral data for this product are shown below in the sequence: 1. 1 NMR, C NMR, 3. Mass, 4. IR. Br, 2 B (unknown) A a. After consideration of the spectral data, write the structure of the product in the box below.

119 Chemistry 3B, Examination 2 Page NMR spectrum (for expanded section, see bottom spectrum). B C D A ppm B C D ppm

120 Chemistry 3B, Examination 2 Page 9 b. Draw again your suggestion for the unknown in the box and label the hydrogens A, B, C, and D giving rise to the corresponding signals in the spectrum. Use the Table below, if necessary.

121 Chemistry 3B, Examination 2 Page C NMR spectrum. B A ppm Draw again your suggestion for the unknown in the box below and label the types of carbon atoms A and B giving rise to the corresponding signals in the spectrum.

122 Chemistry 3B, Examination 2 Page Mass spectrum. int: Atomic weights: C = 12; = 1; = 16; Br exists in nature as a 1:1 mixture of Br = 79 and Br = 81. a. Clearly mark on the spectrum the molecular ion(s) as M +. b. In the boxes above the respective fragment ions, indicate the structure of the fragment.

123 Chemistry 3B, Examination 2 Page IR spectrum. Confirm the presence or absence (circle one) of the following bonds. Enter an approximate expected stretching frequency in the box. ~ ν 3 (Csp ) is: present absent at cm 1 ~ ν ( ) is: present absent at cm 1 ~ ν (C=) is: present absent at cm 1

124 Chemistry 3B, Examination 2 Page 13 IV. [45 Points] Write detailed step-wise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! a. Catalytic Work from left to right in the following spaces. There is more space than you will need.

125 Chemistry 3B, Examination 2 Page 14 b. C 3 CN +, 2 N 2 Work from left to right in the following spaces. There is more space than you will need.

126 Chemistry 3B, Examination 2 Page 15 c., 2 Work from left to right in the following spaces.

127 Chemistry 3B, Examination 2 Page 16 V. [45 Points] Provide a reasonable synthetic route from starting material to product. Note: Several steps are required, and there may be more than one solution to the problem. Do not write mechanisms! Write out each step separately, including reagents and products. You need to apply retrosynthesis! a. N + any other material Work from left to right in the following spaces. There is more space than you will need.

128 Chemistry 3B, Examination 2 Page 17 b. CN Work from left to right in the following spaces. There is more space than you will need.

129 Chemistry 3B, Examination 2 Page 18 c. Synthesize ketone A from starting materials containing one or two carbons only. Work from left to right in the following spaces. There is more space than you will need. A

130 Chemistry 3B, Examination 2 Page 19 VI. [35 Points] Place an X mark in the box next to the most accurate statement. a. The reactivity of 1 4 toward 2 increases in the order C3CCl C 3 CN 2 C 3 CC 3 C 3 CCC , 2, 3, 4 4, 3, 2, 1 2, 3, 4, 1 3, 2, 1, 4 b. The acidity of 1 4 increases in the order C 3 N 3 + C 3 CC 3 C 3 CC 3 C , 2, 3, 4 4, 3, 2, 1 2, 3, 4, 1 3, 2, 1, 4

131 Chemistry 3B, Examination 2 Page 20 c. Explain the following finding in one sentence. For the equilibria shown below, K 1 = ~1, but K 2 > 1 + C 3 + K 1 C K 2 Place your answer into the box below. The End

132 EXAMINATIN 2 Chemistry 3B Name: Print first name before second! Use capital letters! SID #: Peter Vollhardt November 5, 2009 GSI (if you are taking Chem 3BL): Please provide the following information if applicable. Making up an I Grade If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 13 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. (30) II. (30) III. (50) IV. (60) V. (60) VI. (20) Total: (250)

133 Chemistry 3B, Examination 2 Page 2 I. [30 Points] Name or draw, as appropriate, the following molecules according to the IUPAC rules. Indicate stereochemistry where necessary (cis, trans, E, Z, R, or S). a. Cl Br C b. c. (R)-trans-3-Penten-2-amine d. 3-Methyl- N-bromo-N-ethylbutanamide e.

134 Chemistry 3B, Examination 2 Page 3 II. [30 Points] Write the organic products of the following reactions of the starting acyl bromide. Br 2, Br N 3 1. Al Li , 2 work-up 1. (C 3 ) 2 CuLi 2. +, 2 work-up C 3 C

135 Chemistry 3B, Examination 2 Page 4 III. [50 Points] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Aqueous work-up (when required) is assumed to follow each step. It is not part of any answer. a. (C 3 ) 2 N, NaB 3 CN b. 1. LDA 2. C 3 I 3. LiAl 4 c. d.

136 Chemistry 3B, Examination 2 Page 5 e ne pot reaction C 3 f. C C Cl g. 1. PCC 2. +, 2 3. Na, 2, Δ C h. MgBr 2 equiv. C

137 Chemistry 3B, Examination 2 Page 6 i j.

138 Chemistry 3B, Examination 2 Page 7 IV. [60 Points] Write detailed step-wise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! a. Na +- C 2 C 3,C 3 C 2 C 3 C 2 C 3 Work from left to right in the following spaces. There is more space than you will need.

139 Chemistry 3B, Examination 2 Page 8 b. Work from left to right in the following spaces. There is more space than you will need.

140 Chemistry 3B, Examination 2 Page 9 c. The following atom-economical reaction occurs in a dry solvent (this means: no water!). Although it is new to you, you can apply the principles that you have learned to write a mechanism. Work from left to right in the following spaces. There is more space than you will need.

141 Chemistry 3B, Examination 2 Page 10 V. [60 Points] Provide a reasonable synthetic route from starting material to product. Note: Several steps are required, and there may be more than one solution to the problem. Do not write mechanisms! Write out each step separately, including reagents and products. You need to apply retrosynthesis! a. Work from left to right in the following spaces. There is more space than you will need.

142 Chemistry 3B, Examination 2 Page 11 b. Work from left to right in the following spaces. There is more space than you will need.

143 Chemistry 3B, Examination 2 Page 12 c. Synthesize compound A from benzene. Work from left to right in the following spaces. There is more space than you will need.

144 Chemistry 3B, Examination 2 Page 13 VI. [20 Points] Place an X mark in the box next to the most accurate statement. a. The reactivity of 1 4 toward N 3 increases in the order C3CCl 1 2 C 3 CC , 2, 3, 4 4, 3, 2, 1 2, 3, 4, 1 3, 2, 1, 4 b. The acidity of 1 4 (above) increases in the order 1, 2, 3, 4 4, 3, 2, 1 2, 3, 4, 1 3, 2, 1, 4 c. Circle the most likely product of the following reaction: Br 2, excess Br or Br or or The End

145 1 FINAL EXAMINATIN Chemistry 3B Name: Print first name before second! Use capital letters! SID #: Peter Vollhardt May 17, 2006 Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 25 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Grades will be posted on May 25, by 5 pm, outside 320 Latimer all. Good Luck! D NT WRITE IN TIS SPACE I. (60) II. (175) III. (60) IV. (40) V. (60) VI. (60) VII. (45) Total: (500)

146 2 I. [60 Points] Provide the IUPAC name or draw the structure, as appropriate, of the following molecules. Remember the priority of functional groups in choosing names, indicate the correct stereochemistry (e.g., R, S, and E, Z), and do not forget about the alphabetical ordering of substituents! (a) C 2 N (b) Methyl cis-4-bromocyclohexanecarboxylate (c) S

147 3 (d) N CC 2 CC 2 C 3 (e) (4R)-Bromo-N-ethyl-N-methylpentanamide (f) C 2 N C 2 C 2 SC 3 (This is the amino acid methionine)

148 4 II. [175 Points; (a) - (j) 10 points each, (k) - (o) 15 points each] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Aqueous work-up (when required) is assumed to be part of a step. It is not part of any answer. (a) S C 3 C 3 -C 3 S 3 (b) N 3 C C - (c) C 3 hν C 3 13 C NMR: δ = 23.4, 32.9, ppm

149 5 (d) +, 2 1 NMR: δ = 6.20 (s, 2), 2.01 (s, 6) ppm (e) C 3 C 3 CI (f) C 3 C 3 +, C 3 (g) C 3 N 2, Na + NCB 3

150 6 (h) + (i) C 3 (C 3 ) 2 N C N C 3 13 C NMR spectrum of starting material: Mass spectrum of starting material: (j) + Na +, 2

151 7 (k) N 2 CN 3. (l) (m) 1. PBr 3 2. NaCN 3. MgBr 4. +, 2

152 8 (n) N 1. LiAl 4 2. C 3 I (2 equiv) 3. Ag 2 m/z = 99 (o) C C 3 C 3 3 C N C 3

153 9 III. [60 Points] Treatment of chloroacetic acid A with methoxybenzene B and AlCl 3 led to unknown C. The mass, IR, and NMR spectra of this product are shown in the following pages. AlCl 3 ClC 2 C + C 3 C (Unknown) A B (a) After consideration of the spectral data, write the structure of the product in the box below. Structure of unknown b. Interpret the spectral data as requested in the spaces provided, starting on the following page.

154 10 1. Mass Spectrum Label the molecular ion as M + and the base peak as BP. Using the partial periodic table on the previous page for atomic weights, draw the structures of the fragment ions at m/z = 148, 135, and 121, respectively, in the boxes below. Draw a + charge at the point of the dangling valence in your line structure. m/z = 148 m/z = 135 m/z = 121

155 11 2. IR Spectrum Confirm or rule out the presence or absence (circle one) of the following bonds. Enter an approximate expected stretching frequency in the box. ~ ν 3 (Csp ) is: present absent at cm 1 ~ ν 2 (Csp ) is: present absent at cm 1 ~ ν ( ) is: present absent at cm 1 ~ ν (C=) is: present absent at cm 1

156 C NMR Spectrum (scale in ppm). Draw your suggestion for the unknown in the box below and label the types of carbon atoms A, B, C, and D, giving rise to the corresponding signals in the spectrum. Note that B is a group of four signals, which belong to a group of similar carbon atoms, all of which should be labeled B.

157 NMR Spectrum (scale in ppm; for expanded sections, see below and the next page). As indicated on the spectrum above, the signal due to proton A disappears in D 2 solvent ( exchanges ).

158 Draw your suggestion for the unknown in the box and label the hydrogens A E giving rise to the corresponding signals in the spectrum. Note: For the assignment of B and C, consider the effect of close lying substituents. 14

159 IV. [40 Points] You are asked to assign the structures of the two pentoses D-arabinose and D- xylose. Ruff degradation of the former gives D-erythrose, that of the latter D-threose. Kiliani- Fischer extension of D-arabinose furnishes D-glucose and D-mannose, that of D-xylose results in D-gulose and D-idose. 15 C C C 2 C 2 D-(-)-Erythrose D-(-)-Threose D-Arabinose D-Xylose C C C C C 2 C 2 C 2 C 2 D-(+)-Glucose D-(+)-Mannose D-(-)-Gulose D-(-)-Idose 1. Draw your assignments in the respective boxes, using Fischer projections.

160 16 2. Specify the conditions of (a) the Ruff degradation (b) the Kiliani-Fischer extension 1. 2.

161 17 V. [60 Points] Write detailed step-wise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! Work from left to right in the following spaces. There is much more space than you will need. (a) Br Br Na, Br 2 Br

162 18 (b) 1. LiAl , 2, Δ Work from left to right in the following spaces. There is much more space than you will need.

163 19 (c) + C 2 = + C 3 N 2 +, C 3 C 2 3 C N C 3 Work from left to right in the following spaces. There is much more space than you will need.

164 VI. [60 Points] Provide a reasonable synthetic route from starting materials to product. Note: Several steps are required, and there may be more than one solution to the problem. You may use any additional organic or organometallic reagents to effect your conversions. Do not write mechanisms! Br (a) 20 Br Work from left to right in the following spaces. There is much more space than you will need.

165 21 (b) C(C 3 ) 2 2 NCC and 2 NC 2 C Valine Glycine 1. Protection of valine C(C 3 ) 2 2NCCNC 2 C Val-Gly 2. Protection of glycine 3. Dipeptide formation

166 22 (c) Work from left to right in the following spaces. There is much more space than you will need.

167 23 VII. [45 Points] Place an X mark in the box next to the most accurate statement. (a) The longest wavelength band in the UV spectra of the hydrocarbons below moves to lower energy in the order , 2, 3 3, 2, 1 2, 3, 1 3, 1, 2 (b) Circle the compounds which are aromatic N +

168 24 (c) The pk a values of the following compounds decrease in the order C 3 N + N , 2, 3, 4 4, 3, 2, 1 2, 3, 4, 1 3, 4, 2, 1 (d) The rates of electrophilic aromatic nitration of the following compounds increases in the order N 2 N 2 Cl S Cl , 2, 3 2, 1, 3, 3, 2, 1 2, 3, 1

169 25 (e) xidation of idose to idaric acid causes C C N 3 C 2 C Idose Idaric acid the specific rotation to go to zero the 13 C NMR spectrum to simplify to 3 lines the sugar to become reducing mutarotation The End ave a great summer!

170 1 FINAL EXAMINATIN Chemistry 3B Name: Print first name before second! Use capital letters! Peter Vollhardt December 15, 2006 SID #: Laboratory GSI (if applicable): Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 25 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Grades will be posted on Wednesday, December 20, by 5 pm, outside 320 Latimer all. Good Luck! D NT WRITE IN TIS SPACE I. (60) II. (175) III. (60) IV. (40) V. (60) VI. (60) VII. (45) Total: (500)

171 2 I. [60 Points] Provide the IUPAC name or draw the structure, as appropriate, of the following molecules. Remember the priority of functional groups in choosing names, indicate the correct stereochemistry (e.g., R, S, and E, Z), and do not forget about the alphabetical ordering of substituents! (a) (2S)-Amino-6-heptynoic acid (b) Br Cl Cl (c) (R)-2, 3-Dihydroxypropanal

172 3 (d) C 2 C 3 (e) N-(2-Methylpropyl)ethanamide (f)

173 4 II. [175 Points; (a) - (j) 10 points each, (k) - (o) 15 points each] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Aqueous work-up (when required) is assumed to be part of a step. It is not part of any answer. (a) S C 3 Na +- C 3, C 3 (b) 1. N 2 2. C 3 C 3 C 3 C 3 (c)

174 5 (d) P 2 S 5 1 NMR: δ =2.35 (s, 6), 2.01 (s, 6) ppm (e) C 3 N 3, + N (f) C 3, + (g) C 3 N 2, Na + NCB 3

175 6 (h) + CN (i) C 3 C 13 C NMR δ = 220.2, 38.3, 23.3 ppm (j) Na + C 3, C 3 C 3 1 NMR spectrum:

176 7 (k) 1. + N N N (l) C3CC 3 C 3 CC 2 CC 3 (m) 1. C 3, C 3 MgBr +, C 3

177 8 (n) C 3 I 1. NaCN 2. C 3 C 2 C 2 MgBr 3. C 2 =P(C 6 5) 3 Mass spectrum of product: (o) C C 3 C 3 3 C N C 3

178 III. [60 Points] In an attempt to effect electrophilic methoxylation, benzene carbaldehyde A was treated with methyl hydroperoxide B in the presence of acid. The mass, IR, and NMR spectra of this product are shown in the following pages. From the complex mixture of products, traces of unknown C were obtained. 9 + C 3 + C (Unknown) A B (a) After consideration of the spectral data, write the structure of the product in the box below. Structure of unknown b. Interpret the spectral data as requested in the spaces provided, starting on the following page.

179 1. 1 NMR Spectrum (for expanded section, see bottom spectrum). 10

180 11 b. Draw again your suggestion for the unknown in the box and label the hydrogens A, B, C, and D giving rise to the corresponding signals in the spectrum. Use the Table below, if necessary C NMR Spectrum.

181 12 Draw again your suggestion for the unknown in the box below and label the types of carbon atoms A E giving rise to the corresponding signals in the spectrum. 3. Mass spectrum.

182 13 a. Clearly mark on the spectrum the molecular ion as M +. b. In the boxes above the respective fragment ions, indicate the molecular piece that has fragmented from M +, e.g. Cl, or C 3, or C 3 C 2, or? 4. IR Spectrum.

183 14 Confirm or rule out the presence or absence (circle one) of the following bonds. Enter an approximate expected stretching frequency in the box. ~ ν 2 (Csp ) is: present absent at cm 1 ~ ν 3 (Csp ) is: present absent at cm 1 ~ ν ( ) is: present absent at cm 1 ~ ν (C=) is: present absent at cm 1

184 15 IV. [40 Points] You are asked to assign the structures of the two pentoses D-ribose and D- lyxose. Ruff degradation of the former gives D-erythrose, that of the latter D-threose. Kiliani- Fischer extension of D-ribose furnishes D-allose and D-altrose, that of D-lyxose results in D- galactose and D-talose ribose. C C C 2 C 2 D-(-)-Erythrose D-(-)-Threose D-Ribose D-Lyxose C C C C C 2 C 2 C 2 C 2 D-Allose D-Altrose D-Galactose D-Talose 1. Draw your assignments in the respective boxes, using Fischer projections.

185 16 2. Specify the conditions of (a) the Ruff degradation (b) the Kiliani-Fischer extension 1. 2.

186 17 V. [60 Points] Write detailed step-wise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! Work from left to right in the following spaces. There is much more space than you will need. (a) Na, Δ

187 18 (b) N C 3 1. LiAlD , 2 (work up) N C 2 D C 3 Work from left to right in the following spaces. There is much more space than you will need.

188 19 (c) 2N NaB 3 CN, C 3 N Work from left to right in the following spaces. There is much more space than you will need.

189 VI. [60 Points] Provide a reasonable synthetic route from starting materials to product. Note: Several steps are required, and there may be more than one solution to the problem. You may use any additional organic or organometallic reagents to effect your conversions. Do not write mechanisms! (a) 20 N Work from left to right in the following spaces. There is much more space than you will need.

190 21 (b) 2 N C 2 N CN C

191 22 (c) The only organic starting materials: N N C 3 C 3 Work from left to right in the following spaces. There is much more space than you will need.

192 23 VII. [45 Points] Place an X mark in the box next to the most accurate statement. (a) The longest wavelength band in the UV spectra of the hydrocarbons below moves to lower energy in the order , 2, 3 3, 2, 1 2, 1, 3 3, 1, 2 (b) Circle the compounds which are aromatic 2 N N N N N +

193 (c) In the collection below, circle the most abundant fragments formed during the mass spectral ionization of 2-pentanone ev + C C 3 + C 3 C 2 + C 2 + 3C 2 C C C (d) The rates of electrophilic aromatic nitration of the following compounds increases in the order Cl N Cl N C , 2, 3 2, 1, 3, 3, 2, 1 2, 3, 1

194 25 (e) Give the products and their molar amounts per mole of starting material of the complete periodic acid oxidation of D-erythrose and D-erythrulose. C C 2 I 4 D-Erythrose C 2 C 2 D-Erythrulose The End Merry Christmas!

195 1 FINAL EXAMINATIN Chemistry 3B Name: Print first name before second! Use capital letters! Peter Vollhardt December 17, 2008 SID #: Laboratory GSI (if applicable): Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 25 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. (60) II. (175) III. (60) IV. (40) V. (60) VI. (60) VII. (45) Total: (500)

196 2 I. [60 Points] Provide the IUPAC name or draw the structure, as appropriate, of the following molecules. Remember the priority of functional groups in choosing names and indicate the correct stereochemistry (cis, trans, E, Z, R, and S, as appropriate)! (a) Trans-3-oxo-4-hexenal (b) 1-Bromo-4-(2,2-dichloropropyl)benzene (c) (R)-2,3-Dihydroxypropanenitrile (Fischer projection) The numbers refer to the main chain

197 3 (d) 2 N C 2 C 3 (e) N-Chloro-N-methyl-3-pentanamine (f)

198 4 II. [175 Points; (a) - (j) 10 points each, (k) - (o) 15 points each] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Aqueous work-up (when required) is assumed to be part of a step. It is not part of any answer. (a) S C 3 + Na + C 3 (b) 1. 3 C N C I 3 C C 3 C 3 C 3 (c)

199 5 (d) N 3, + 13 C NMR spectrum: (e) 3 C N N 3, + N 2 (f) C 3 3 C 3 C 3 C C 3 2, + mildly acidic

200 6 (g) C 3 N Two reagents (h) 3 C CN + CN (i) + Na 2 N N 2

201 7 (j) 1. LiAl , 2 3 C IR spectrum of starting material: 13 C NMR spectrum of starting material:

202 8 (k) C (l) Br 3. N 2 (m) N 2 I 4 2 C + 1 C 2 = An aldose

203 9 (n) 1. N Br 2. C 3 Mass spectrum of product: 1 NMR spectrum of product: ppm (o) 1. Mn 2 2. N N 2 C

204 III. [60 Points] Diethyl malonate A was treated with bromine to give a product B. The mass, IR, and NMR spectra of B are shown in the following pages in the sequence : 1. 1 NMR, C NMR, 3. Mass, 4. IR. 10 Br 2 B A (a) After consideration of the spectral data, write the structure of B in the box below. Structure of B

205 NMR spectrum (for expanded sections, see bottom spectra). C B A ppm B (J = 8 z) C ( J = 8 z) A ppm ppm

206 b. Draw again your suggestion for B in the box and label the hydrogens A, B, and C giving rise to the corresponding signals in the 1 NMR spectrum. Use the Table below, if necessary. 12

207 C NMR spectrum. D B A C

208 14 Draw again your suggestion for B in the box below and label the types of carbon atoms A D giving rise to the corresponding signals in the spectrum. 3. Mass spectrum. int: Atomic weights: C = 12; = 1; = 16; Br exists in nature as a 1:1 mixture of Br = 79 and Br = 81. a. Clearly mark on the spectrum the molecular ion(s) M +. b. In the boxes below, indicate the structure of the fragment ions with the m/z value given under the box. m/z = 193/195 29

209 15 4. IR Spectrum. Confirm the presence or absence (circle one) of the following bonds. Enter an approximate expected stretching frequency in the box. ~ ν 2 (Csp ) is: present absent at cm 1 ~ ν 3 (Csp ) is: present absent at cm 1 ~ ν ( ) is: present absent at cm 1 ~ ν (C=) is: present absent at cm 1

210 IV. [40 Points] (a) D-Ribulose is a non-reducing pentose. Treatment with NaB 4 gives two alditols. ne of them is identical to the product of NaB 4 reduction of D-ribose, the other is identical to the product of NaB 4 reduction of D-arabinose. Fill in the blanks below and provide a structure for D-ribulose. 16 NaB 4 D-Ribulose An alditol An alditol NaB 4 NaB 4 C C C 2 D-Ribose C 2 D-Arabinose (b) D-Erythrose was treated with aqueous bromine to give the aldonic acid A, which was subsequently thermally dehydrated to B, and then treated with acidic acetone to give the final product C. Provide structures for A and B. C Br 2, 2 Δ 2 C 2 D-Erythrose A B +, 3 C C 3 C 2 Note: These "corners" are not atoms. C 3 C 3 C 2 C

211 17 V. [60 Points] Write detailed step-wise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! (a) Work from left to right in the following spaces. There is much more space than you will need. 3 C + Na, 2, Δ C 3 C 3

212 18 (b) Br 2 N 2 Na, 2 2 N N 2 Work from left to right in the following spaces. There is much more space than you will need. N 2

213 19 (c) +, 2 C 3 3 C C 3 C 3 Work from left to right in the following spaces. There is much more space than you will need.

214 VI. [60 Points] Provide a reasonable synthetic route from starting material to product. Note: Several steps are required, and there may be more than one solution to the problem. Do not write mechanisms! Write out each step separately, including reagents and products. You need to apply retrosynthesis! You may use any additional organic or organometallic reagents to effect your conversions. (a) 20 N 2 Note: CCl, CCl, 2 NCCl, and ClC 2 N 2 do not exist and are not allowed as reagents. N Work from left to right in the following spaces. There is much more space than you will need.

215 21 (b) C C 2 N N 2 N

216 22 (c) For this problem, use the materials given below as the only organic compounds: I Starting material I Additional organic reagents Work from left to right in the following spaces. There is much more space than you will need.

217 23 VII. [45 Points] Place an X mark in the box next to the most accurate statement. (a) The acidity of 1 4 increases in the order C 3 N 3 3 NC 2 C C 3 C N , 2, 3, 4 4, 3, 2, 1 4, 1, 2, 3 3, 2, 1, 4 (b) In the 1 NMR spectrum of the compund below circle the hydrogens that you expect to show peaks in the left half of the spectrum (that is δ > 5 ppm). Cl N N

218 24 (c) The following Diels-Alder reaction follows the endo rule. True or false? Circle the correct answer below C 3 C 3 C 2 C 3 + C 2 C 3 C 2 C 3 C 2 C 3 True False (d) The mass spectrum of N,N-dipropylpropanamine (see below) shows only a relatively small molecular ion peak at m/z = 143. The base (100%) peak is a fragment at m/z = 114. In the box below the spectrum, draw the structure of this fragment (including charges). N N,N-dipropylpropanamine

219 (e) Aromatic heterocycles are frequently constructed in one step by a combination of aldol and imine condensations. With this statement in mind provide the most suitable retrosynthetic disconnection of A into two starting materials (boxes). 25 C 3 C 3 + A N C 3 The End Merry Christmas!

220 1 FINAL EXAMINATIN Chemistry 3B Name: Print first name before second! Use capital letters! SID #: GSI (if you are taking Chem 3BL): Peter Vollhardt December 16, 2009 Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 19 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. II. III. IV. V. VI. VII. (60) (175) (60) (40) (60) (60) (45) Total: (500)

221 2 I. [60 Points] Name or draw, as appropriate, the following molecules according to the IUPAC rules. Indicate stereochemistry where necessary (cis, trans, E, Z, R, or S). (a) (R)-4-bromo-N-ethyl-N-methyl-pentanamide (b) 1-Bromo-4-(2,2-dichloropropyl)benzene (c) (R)-2,3-Dihydroxypropanal (Fischer projection) The numbers refer to the main chain

222 3 (d) (e) Methyl 3-oxo-butanoate (f)

223 4 II. [175 Points; (a) - (j) 10 points each, (k) - (o) 15 points each] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Aqueous work-up (when required) is assumed to be part of a step. It is not part of any answer. (a) 2, Pd C (b) C C N C C 3 (c)

224 5 (d) (e) (f) (g) 2 C= + NaB 3 CN, C 3 C 3 N

225 6 (h) C 3 Complete the stencil above (i) 3 C (j) 3 C

226 7 (k) (l) (m) I 4 2 C + 1 C 2 = An aldose

227 8 (n) (o) 1. Mn 2 2. N 4 CN 3. +, 2, Δ

228 III. [60 Points] The wavy lines in the following structure indicate four possible retrosynthetic disconnections of four bonds (numbered 1-4) Show the respective four reactions that would lead to the generation of each of these strategic bonds in the four boxes below. Note: It is fine to use a protected or otherwise modified fragment to make the desired connection, as long as it can be elaborated later into the target structure. owever, do not show such elaboration. Each box should contain only the reagents that you would use to make the bond in question. Bond 1: Bond 2: Bond 3: Bond 4:

229 IV. [40 Points] (a) D-Ribulose is a pentaketose. Treatment with NaB 4 gives two alditols. ne of them is identical to the product of NaB 4 reduction of D-ribose, the other is identical to the product of NaB 4 reduction of D-arabinose. Fill in the blanks below and provide a structure for D-ribulose. 10 NaB 4 D-Ribulose An alditol An alditol NaB 4 NaB 4 C C 2 D-Ribose C C 2 D-Arabinose (b) D-Erythrose was treated with nitric acid to give the aldaric acid A, which was treated with acidic acetone to give B. n heating, B dehydrated to the final product C. Provide structures for A and B.

230 V. [60 Points] Write detailed step-wise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! Work from left to right in the following spaces. There is more space than you will need. (a) 11 +, 2, TF

231 12 (b) +, 2 Work from left to right in the following spaces. There is much more space than you will need.

232 13 (c) +, 2, Δ Work from left to right in the following spaces. There is much more space than you will need.

233 VI. [60 Points] Provide a reasonable synthetic route from starting material to product. Note: Several steps are required, and there may be more than one solution to the problem. Do not write mechanisms! Write out each step separately, including reagents and products. You need to apply retrosynthesis! You may use any additional organic or organometallic reagents to effect your conversions. (a) 14 Work from left to right in the following spaces. There is much more space than you will need.

234 15 (b) N 2 C S S N Work from left to right in the following spaces. There is much more space than you will need.

235 16 (c) Work from left to right in the following spaces. There is much more space than you will need.

236 17 VII. [45 Points] Place an X mark in the box next to the most accurate statement. (a) The acidity of 1 4 increases in the order: C 3 N 3 3 NC 2 C C 3 C N , 2, 3, 4 4, 3, 2, 1 1, 4, 2, 3 3, 2, 1, 4 (b) The following two sugars are: C C 2 C 2 C Identical Enantiomers Diastereomers Anomers

237 18 (c) The following heterocycle will undergo electrophilic bromination at position: N N S (d) The following reaction will give Na + C 2 C 3,C 3 C 2

238 19 (e) Which of the following molecules are reduced by LiAl 4? Check all the boxes that apply. N Cl The End Merry Christmas!

239 1 EXAMINATIN 1 Chemistry 3B Name: Print first name before second! Use capital letters! SID #: Peter Vollhardt September 23, 2010 GSI (if you are taking Chem 3BL): Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 15 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. (30) II. (30) III. (50) IV. (40) V. (40) VI. (40) VII. (20) Total: (250)

240 I. [30 Points] Name or draw, as appropriate, the following molecules according to the IUPAC rules. Indicate stereochemistry where necessary (cis, trans, E, Z, R, or S). 2 a. (S)-1-(2-Chlorobutyl)-2-nitrobenzene b. cis-exa-1,3-diene c. C 3 C 3 Pure enantiomer d.

241 3 e. 4-xopentanal II. [30 Points] Compound A undergoes preferential electrophilic nitration to give only one product. CF 3 CF 3 CF 3 CF N 2 2 N N 3, 2 S 4 or or N A a. Which one? Mark the box below your choice with an X, preferably after you have completed questions b. d. b. Write all the resonance forms of the intermediate formed by attack of N 2 + on A at: CF 3 C-2: Note: A first stencil is provided for format. Leave out the numbering in any additional structures. Write the nitro group as N 2 (no need for the Lewis structure).

242 4 CF 3 C-5: Note: A first stencil is provided for format. Leave out the numbering in any additional structures. Write the nitro group as N 2 (no need for the Lewis structure). CF 3 C-6: Note: A first stencil is provided for format. Leave out the numbering in any additional structures. Write the nitro group as N 2 (no need for the Lewis structure). c. Circle (in your answers above) the most strongly contributing resonance forms of the attack at C-2, C-5, and C-6. d. Considering all of the above most strongly contributing resonance forms, which one is the best overall? Redraw it in the box below. CF

243 III. [50 Points] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Show stereochemistry when appropriate. Aqueous work-up (when required) is assumed to be part of a step. It is not part of any answer. 5 a. Two isomers. Add the missing pieces. b. Br 2 C Br 2 Kinetic product Thermodynamic product int: Electrophilic attack occurs preferentially at C-1.

244 6 c. C 3 CN + CN Complete the stencil above, showing clearly stereochemistry (hashed and wedged bonds). d. hν Product of ring opening e. Mn 2

245 7 f g. C 3 3 S N 3, 2 S 4 2 N F h. 2 N Br 2,FeBr 3 Cl Monobromination

246 8 i. j C C C , 2 3 C C C 3 S 3, 2 S 4 2 N

247 9 IV. [40 Points] a. Rank the following arenes in order of reactivity (highest to lowest) toward electrophilic aromatic substitution. Mark the box next to the best answer below. Cl C 3 N 2 Br CF , 2, 3, 4 3, 1, 2, 4 3, 2, 1, 4 3, 1, 4, 2 b. Among the compounds shown below, circle those that are stabilized by conjugation.

248 10 c. ne of the compounds shown below is aromatic. Circle its structure. C 3 C 3 d. Rank compounds 1 5 in order of increasing reactivity as dienes in the Diels-Alder reaction: 1, 2, 3, 4, 5 1, 4, 2, 3, 5 3, 1, 5, 4, 2 5, 3, 1, 4, 2 3, 5, 1, 2, 4

249 11 V. [40 Points] Write detailed stepwise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! a. Work from left to right in the following spaces. There is much more space than you will need.

250 b. ydrocarbon A is doubly deprotonated by methyllithium to give the aromatic dianion B. Treatment of B with bromine at low temperatures gave C. Write a plausible mechanism that leads from B to C. 12 Work from left to right in the following spaces. There is much more space than you will need.

251 VI. [40 Points] Provide a reasonable synthetic route from starting material to product. Note: Several steps are required, and there may be more than one solution to the problem. Do not write mechanisms! Write out each step separately, including reagents and products. 13 a. Work from left to right in the following spaces. There is much more space than you will need.

252 14 b. Synthesize compound A from any acyclic materials and any other reagent. int: Think Diels-Alder reaction. Caution: Work backwards. C 2 C 3 A (racemate) Work from left to right in the following spaces. There is much more space than you will need.

253 15 VII. [20 Points] Place an X mark in the box next to the most accurate statement. a. The Diels-Alder reaction is made possible because a racemate is formed the (4N+2) rule overrides the Lewis octet rule of two isomeric products the less stable one is formed the reaction requires heat to go to completion an aromatic transition state b. The bromine substituent in bromobenzene directs electrophiles ortho/para because it is inductively donating it is inductively electron-withdrawing it stabilizes the cationic intermediates by resonance it is sterically hindered it is an electron acceptor by resonance The End

254 EXAMINATIN 2 Chemistry 3B Name: Print first name before second! Use capital letters! SID #: Peter Vollhardt ctober 28, 2010 GSI (if you are taking Chem 3BL): Please provide the following information if applicable. Making up an I Grade If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 13 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. (30) II. (30) III. (50) IV. (60) V. (60) VI. (20) Total: (250)

255 Chemistry 3B, Examination 2 Page 2 I. [30 Points] Name or draw, as appropriate, the following molecules according to the IUPAC rules. Indicate stereochemistry where necessary (cis, trans, E, Z, R, or S). a. b. N-Methylpent-2-ynamide c. 2 N C d. Br e. (Z)-4-ydroxybut-2-enal

256 Chemistry 3B, Examination 2 Page 3 II. [30 Points] Write the organic products of the following reactions of the starting ester. Neutralizing aqueous work up is assumed. (C 3 ) 2 N, 250 C 1. N Li + 2. Molecular formula = C LiAl 4 C 3 MgBr (2 equiv) Na, 2

257 Chemistry 3B, Examination 2 Page 4 III. [50 Points] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Aqueous work-up (when required) is assumed to follow each step. It is not part of any answer. a. C 3 C 2, C 3 C 2 Na + b. 1. LDA 2. C 3 I 3. LiAl 4 c. 2 d.

258 Chemistry 3B, Examination 2 Page 5 e. Br Br + f. PCl 5 g h. C 3 CN MgBr

259 Chemistry 3B, Examination 2 Page 6 i. j. NaCNB 3, C 3

260 Chemistry 3B, Examination 2 Page 7 IV. [60 Points] Write detailed step-wise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! a. catalytic 2 S 4, TF Work from left to right in the following spaces. There is more space than you will need.

261 Chemistry 3B, Examination 2 Page 8 b. Work from left to right in the following spaces. There is more space than you will need.

262 Chemistry 3B, Examination 2 Page 9 c. Work from left to right in the following spaces. There is more space than you will need.

263 Chemistry 3B, Examination 2 Page 10 V. [60 Points] Provide a reasonable synthetic route from starting material to product. Note: Several steps are required, and there may be more than one solution to the problem. Do not write mechanisms! Write out each step separately, including reagents and products. Apply retrosynthesis! It will help you obtain at least partial credit. a. You may use any additional simple reagents. NC 3 and as starting materials Work from left to right in the following spaces. There is more space than you will need.

264 Chemistry 3B, Examination 2 Page 11 b. Work from left to right in the following spaces. There is more space than you will need.

265 Chemistry 3B, Examination 2 Page 12 c. Synthesize compound A from benzene. Work from left to right in the following spaces. There is more space than you will need.

266 Chemistry 3B, Examination 2 Page 13 VI. [20 Points] Place an X mark in the box next to the most accurate statement. a. The equilibrium constant K for the hydration of 1 4 increases in the order 1, 2, 3, 4 4, 3, 2, 1 2, 3, 4, 1 2, 3, 1, 4 b. The basicity of 1 4 increases in the order 1, 2, 3, 4 4, 3, 2, 1 2, 1, 4, 3 3, 2, 1, 4 They failed Chem 3B. The End

267 1 FINAL EXAMINATIN Chemistry 3B Name: Print first name before second! Use capital letters! SID #: GSI (if you are taking Chem 3BL): Peter Vollhardt December 15, 2010 Please provide the following information if applicable. Making up an I Grade (If you are, please indicate the semester during which you took previous Chem 3B: Semester Instructor Please write the answer you wish to be graded in the spaces provided. Do scratch work on the back of the pages. This test should have 19 numbered pages. Check to make sure that you have received a complete exam. A good piece of advice: Read carefully over the questions (at least twice); make sure that you understand exactly what is being asked; avoid sloppy structures or phrases. It is better to be pedantic in accuracy now than sorry later! Good Luck! D NT WRITE IN TIS SPACE I. II. III. IV. V. VI. VII. (60) (175) (60) (40) (60) (60) (45) Total: (500)

268 2 I. [60 Points] Name or draw, as appropriate, the following molecules according to the IUPAC rules. Indicate stereochemistry where necessary (cis, trans, E, Z, R, or S). (a) N (b) 2-Chloro-1-methyl-4-(2-propenyl)benzene (c)

269 3 (d) (e) 4-Fluoro-2-iodopyrrole (f) N-Ethyl-3-methylpent-4-ene-1-amine

270 4 II. [175 Points; (a) (j) 10 points each, (k) (o) 15 points each] Add the missing components (starting materials, reagents, or products) of the following reactions in the boxes provided. Aqueous work-up (when required) is assumed to be part of a step. It is not part of any answer. (a) Cl 2 (b) 1. Cl 2. N 2 C 3 C 3 (c) Δ

271 5 (d) 1. N N (e) (f)

272 6 (g) NC CN 2 C= + N 3 + N (h) (i) Na + C 3, C 3, Δ C 3 (j) 1. Li 2.

273 7 (k) MgBr (l) Δ (m) I 4 1 C + 2 C 2 = + 1 C 2 A D-ketose

274 8 (n) C 6 13 N (o) 1. Mn N 4 CN 3. +, 2, Δ

275 III. [60 Points] The wavy lines in the following structure indicate four possible retrosynthetic disconnections of four bonds (numbered 1-4) N Show the respective four reactions that would lead to the generation of each of these strategic bonds in the four boxes below. Note: It is fine to use a protected or otherwise modified fragment to make the desired connection, as long as it can be elaborated later into the target structure. owever, do not show such elaboration. Each box should contain only the reagents that you would use to make the bond in question. Bond 1: Bond 2: Bond 3: Bond 4:

276 IV. [40 Points] In water, ribose exists mainly in its cyclic furanose form (both structures are shown below). A researcher finds a bottle of ribose monomethyl ether and wants to know the position of the methoxy group. There are five options, indicated by boxes in the two structures given for ribose. NaB 4 reduction of ribose monomethyl ether gave an optically active compound A. N 3 produced optically active dicarboxylic acid B. Ruff degradation of ribose monomethyl ether, followed by NaB 4 reduction led to optically active compound C. Fill in the blank boxes below with the structures of A, B, C, and ribose monomethyl ether. 10 NaB 4 Ribose monomethyl ether A A 1. Ruff degradation 2. NaB 4 B C

277 11 V. [60 Points] Write detailed step-wise mechanisms for the following transformations. Use only structures and arrow-pushing techniques. Note: These are not synthetic problems. Do not add any reagents! What you see is what you have! (a) Work from left to right in the following spaces. There is more space than you will need.

278 12 (b) Work from left to right in the following spaces. There is much more space than you will need.

279 13 (c) int: There is no water. Work from left to right in the following spaces. There is much more space than you will need.

280 VI. [60 Points] Provide a reasonable synthetic route from starting material to product. Note: Several steps are required, and there may be more than one solution to the problem. Do not write mechanisms! Write out each step separately, including reagents and products. Apply retrosynthesis! It will help you obtain at least partial credit. (a) 14 Work from left to right in the following spaces. There is much more space than you will need.

281 15 (b) Work from left to right in the following spaces. There is much more space than you will need.

282 16 (c) You may use additional organic or organometallic reagents containing seven carbons or less to effect your conversions. Work from left to right in the following spaces. There is much more space than you will need.

283 17 VII. [45 Points] Place an X mark in the box next to the most accurate statement. (a) The product of the following Diels-Alder reaction is + C 3 C 3 endo exo entropically favored kinetically disfavored (b) Show by an arrow the most likely site of protonation of the following molecule: N N 2 2 N N N

284 18 (c) In the following molecule, circle all possible sites of reduction by excess LiAl 4 : CN N C 3 (d) The following scheme describes part of an industrial synthesis of the drug Chantix. ne step will not work. Circle which one ,Pt C C 6 5 C 2 N 2, +, 2,Pt NC 2 C 6 5 +, 2 C N CF 3CCCF 3 NCCF 3 N 3, + 2 N NCCF 3 2 N

285 19 (e) Circle the most thermodynamically stable of the following isomers: The End Merry Christmas!