1.5 h; 120 points please print clearly Dr. Kathleen Nolta Dr. Jordan Walk. Problem Points Score GSI I 23 II 27 III 24 IV 22 V 24 Total 120

Transcription

1 hemistry 10 econd Examination First ame Last ame 1.5 h; 10 points please print clearly Dr. Kathleen olta Dr. Jordan Walk ignature UM ID # PRIT TE FIRT LETTER F YUR LAT AME ERE: Problem Points core GI I II 7 III IV V Total 10 omplete Lewis structures are required unless you are given other specific instructions. Precision in drawing counts. heck all three-dimensional representations to ensure you are implying an unequivocal direction of bonding. Do not forget to include important features such as nonbonding electron pairs and formal charges when appropriate. Individual point values are given in the corner of each answer space. The exam has 6 pages in addition to this cover page. A pka table is on the last page.

2 I. ( points) Valnoctamides have been used as sedatives and inducers of hypnosis for decades. The most biologically active molecule from this class of compounds is shown. Using ewman projections, analyze two of the bonds in this molecule. view 1 - view - 1 Valnoctamide-1 ame Page 1 (a) Draw a ewman projection of the 1 - bond in Valnoctamide-1 in the conformation shown; view with the 1 in front. (b) Draw a ewman projection of the - bond in Valnoctamide-1 in the conformation shown; view with the in front. (c) Draw a ewman projection of the - bond in Valnoctamide-1 after a 180 bond rotation; continue to view with the in front bond rotation (d) Describe the relationship (if any) between the drawing (and conformation) of Valnoctamide-1provided for you in part (a) above and each of the drawings (P, Q, R, and ) shown below. heck all the descriptions that apply when comparing valnoctamide-1 (above) with each of these other drawings. (i) (ii) (iii) (iv) P Q R valnoctamide-1 with P, valnoctamide-1 with Q, valnoctamide-1 with R, valnoctamide-1 with,

3 II. (7 points) ame Page A. Telapravir is an antiviral drug that acts as a protease inhibitor. It has been a very successful treatment for hepatitis. It was approved for use in 011. ircle and label every chiral (tetrahedral) stereocenter in Telaprevir. Telaprevir 18 B. onvert name to structure or structure to name as needed. Be sure to include all information on connectivity and stereochemistry in both your drawings and your naming. (i) Draw this compound: ()-1-cyclobutyl-6-propylcyclohex-1-ene (ii) ame this compound: Br This compound should show: 1 MR signals with ratio 1

4 A. III. ( points) The transformation shown (M to F) demonstrates a highly regioselective addition of methanol. Draw the stepwise, curved arrow mechanism for this complete transformation. Be sure to use appropriate acid/base choices, and clearly show the resonance effect that explains this regioselection. Ignore stereochemistry. M ame Page (cat.) ompound F ompound F 1 B. The energy diagram shown could represent the transformation you have shown above in conjunction with the formation of the regioisomeric product, Q. Provide the structure of the missing regioisomer and answer questions about the energy diagram using positional labels. L (i) Define the E a for the rate determining step in the formation of Q: A (iii) Under reversible reaction conditions the favored product is: (ii) Draw Q; if the product forms as a stereoisomeric mixture, draw one showing stereochemistry clearly and write "+ enantiomer" or "+ diastereomer" in the box. Energy Q P M B starting materials M D E F (iv) Define the ΔG rxn for the formation of F? reaction progress reaction progress + ompound F +

5 A. IV. ( points) ame Page Provide the structures of all starting materials with structural formula 1 that can lead to the product shown. Be sure to draw them in the box with the matching MR data. 1 isomers, 1 -MR: 10 draw all possible starting materials 1 -MR: 6 (cat.) according to -MR data 6 B. omplete the following reaction by providing missing product(s). If more than one compound can be formed, only provide one drawing and discuss the other products in (ii). (i) (ii) This ionic compound product forms l () with only its enantiomer with only one diastereomeric molecule with >1 stereoisomer with regioisomer(s) alone, with no other isomers (iii) Provide a transition state drawing that represents the single step that occurs in this reaction. The missing starting material ( 1 10 ) yields only product(s) with molecular formula Provide the missing information. (i) 1 10 (1 equivalent) (cat.) (ii) This organic product forms with only its enantiomer with only one diastereomeric molecule with >1 stereoisomer with regioisomer(s) and stereoisomers alone, with no other isomers (iii) Provide a transition state drawing that represents the ratedetermining step that occurs in this multi-step reaction. Be sure to choose your reactants carefully.

6 V. ( points) The following addition reaction yields mainly stereoisomeric products, and. Provide the structure of. ame Page 5 (a) other product l l + 1 (b) Describe the relationship (if any) between the drawings indicated. heck all the descriptions that apply. (i) compound 1 with A, (ii) compound with B, the l the A B (c) Draw the two chair conformations for ompound and indicate the K eq for your pair of chairs. As always, be sure to clearly and accurately show the axial and equatorial positions for all substituted ring atoms. You do not have to show axial and equatorial hydrogen atoms for unsubstituted ring atoms. circle one K eq > 1 = 1 < 1 1 (d) Based on the conformational analysis you have done for compound, what do you predict about the relative amounts of each product ( and ) that forms? ircle one of the options and explain. ompound > ompound ompound < ompound ompound = ompound Briefly explain:

7 AID (trongest Acid) l I l F pk a JUGATE BAE (Weakest Base) -1 l -7. I l -.6 F AID l l l pk a JUGATE BAE l l l (Weakest Acid) 9 (trongest Base)