R or S? 2) oxidation numbers of the designated carbon atoms: note: An oxidation number must have a sign. F 3 C OCH 3 oxidation #: OH.

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2 ame 5 F0-Exam o. Page I. ( points) The following compounds are those used in our study on the mechanism of the chemical carcinogenesis of benzo[a]pyrene. ) Designate in each of the boxes below the stereochemistry (R or ) at the indicate carbon center and ) provide in each of the boxes provided the formal oxidation number of each of the indicated carbon atoms. ) stereochemistry (R or ) of the designated carbon centers: R or? R or? R or? F C C F C C R or? R or? ) oxidation numbers of the designated carbon atoms: note: An oxidation number must have a sign. oxidation #: oxidation #: F C C oxidation #: oxidation #: II. (0 points) Write in the boxes below the expected hybridization of each of the indicated atoms (i.e., sp, sp, or sp) in the following molecules. C C C

3 ame 5 F0-Exam o. Page III. (0 points) The two-step wern oxidation of a secondary alcohol provides the corresponding ketone as shown below. The intermediate produced after step is a sulfoxonium ion. Treatment of the sulfoxonium ion with a bulky base (step ) results in the formation of the ketone. D. C C When mono-deuterated cyclohexanol is subjected to dioxalyl chloride and dimethyl sulfoxide (i.e., step above), mono-deutrated sulfoxonium ion is produced. This then undergoes oxidation upon treatment with triethylamine [(C C ) ] and the D label ends up in dimethyl sulfide as shown below. D C C. C C D n the basis of the information given above, propose in the box below a step-by-step, curved-arrow mechanism for the formation of cyclohexanone () from the sulfoxonium ion intermediate (). C C D (C C ) C C D IV. (0 points) In the box below, write a step-by step, curved-arrow mechanism for the following reaction [J. rg. Chem. 00, 75, 69]. C C C C C * 0 *ften drawn as: Mechanism: C C C C C C C 0

4 Remember Lone pair-assisted ionization. ame 5 F0-Exam o. Page V. ( points) [Eur. J. rg. Chem. 00, 65] Treatment of diol with acetal 5 in the presence of a catalytic amount of p-toluenesulfonic acid (Ts; pka -0.5) results in the formation of a new acetal, 6, shown below. Draw the structure of the expected uncharged acetal intermediate in the designated box below and propose in the box below a step-by-step, curved-arrow reaction mechanism for this transformation from the diol to acetal 6. You may use -A and A- for the acid Ts and its conjugate base, respectively. You do not need to balance each step. I C C Ar -A 5 6 I Ar C ote: Ar = C (i) Draw the mechanism through the formation of the uncharged acetal intermediate. 5 C Ar C A I (ii) Draw the mechanism through the formation of the acetal product, 6. uncharged acetal intermediate Ar I acetal product (6)

5 ame 5 F0-Exam o. Page 5 VI. ( points) Complete the following reaction sequences by providing in each of the boxes the structure of the corresponding starting compound or product. If more than one stereoisomer would be formed for a product, draw one of the stereoisomers and write enantiomer or diastereomer in the box. () [ucleosides, ucleotides and ucleic Acids 00, 9, 6] (MCPBA) a a () [J. rg. Chem. 00, 75, 6]. C Mg. aq K (acidic) Δ (heat) C 6 6 C 7 8 s (mol equiv) () [ynlett 00, ] C C a a

6 ame 5 F0-Exam o. Page 6 VII. ( points) Complete the following reaction sequences by providing in each of the boxes the structure of the corresponding starting intermediate or product. If more than one stereoisomer would be formed for a product, draw one of the stereoisomers and write enantiomer or diastereomer in the box. () C two stereoisomeric bromonium ion intermediates C 7 () [ynlett 00, 6] C () [ynthesis 00, ] F PCC (C C ) CF () [rg. Lett. 00,, 07] Ts,

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9 Reagent List Page 9 hown below is a list of key reagents (not always the whole recipe) that may be useful for solving questions on the exam #. reagent classification or specialized use From Chem 0 s / oxidation KMn oxidation peroxyacid epoxidation (e.g., - or meta-chloroperoxybenzoic acid [MCPBA]*) i. ; ii. (C ) or Zn ozonolysis i. ; ii. ozonolysis a base, nucleophile a base KC(C ) bulky base /Pd hydrogenation /Pd, Ba, quinoline hydrogenation i. B or 9-BB;* ii., a hydroboration P e.g., R- R- e.g., R- R- p-c C 6 (Ts) tosylate formation C (Ms) mesylate formation -bromosuccinimide (B)* source of electrophilic ========================================================================= Chapter C 5 5 Cr - (pyridinium chlorochromate [PCC]* oxidant Cr / / /acetone oxidant i. C(=)-C(=), (C ) ; ii. (C C ) oxidant Chapter ab nucleophilic hydride LiAl nucleophilic hydride diisobutylaluminum hydride nucleophilic hydride (DIBAL) a(c)b nucleophilic hydride RMgX nucleophilic carbon RLi nucelophilic carbon -C C 6 (Ts) organic-soluble acid * MCPBA Raney i C C BF (C C ) B 9-BB Lewis acid B desulfurization thioacetal/thioketal formation hydrazone formation oxime formation Cr PCC