chem_302_april2005

Chem_302_april2005 - FACULTY OF SCIENCE FINAL EXAMINATION CHEMISTRY 180~302.01(winter Organic Chemistry Ill Examiners G Just Monday N Moitessier

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Unformatted text preview: FACULTY OF SCIENCE FINAL EXAMINATION CHEMISTRY 180~302.01 (winter) Organic Chemistry Ill Examiners: G. Just Monday, April 18, 2005 N. Moitessier 14.00-17.00 Student name: Student number: There are 10 questions in this examination. Questions 1-3 correspond to the first class test, and questions 4—6 to the second class test. Questions 1—3 may be rewritten for those who wish to improve their mark. Students who have written class test 2 in March can only answer part 3 (Questions 740), unless a special permission has been granted to rewrite part 2. No models, calculators etc. finswm on exam o/NV‘ Chemistry 302 winter, page 1 1a) Draw the conformation of a-D-mannopyranose, a-L-galactopyranose, u-D-glucofuranose, oc-D— mannofuranose and a-D-galactofuranose (5) 1b) Provide a detailed mechanism for the foilowing transformation (5) HOH HO” CH3OH, H69 Ho H HO H a0 7 O H go 0 H H OH H OCH3 Chemistry 302, page 2, question 2 (10) Provide all intermediates and reaction conditions for the synthesis of cellobiose from 1 and 2, and show why the formation of the glycosidic bond is stereospecific. OA HOH OH H c O H HO 0 H9. H0 ACO + O O AcO AcO H —*—> ,0 Ho OH 0 /O H H H ,0 1’ Br H H 1 2 Cellobiose Chemistry 302, page 3, question 3 How would you prepare AZT (3'—deoxy-3'~azid0thymidine) from thymidine (10) HO H OH H thymidine Chemistry 302 winter, page 4 4. Provide reagents and mechanisms for reactions 3, b and c (10) Ac \OOAC AC‘QOAC AC \QOAC O a O b O C ACO H —» AcO H ACO H /NH [’NH AC/ 0 AC 0 AC 0 \ PO(OMe)3 NHBOC AC \OOAC \ O \ O BOCHN COOCHzCstiMeg C \ O/ \O ACO H > /NH - AC 0 M93SI \ NHBOC Ce HO” O Chemistry 302 winter, page 5 5).Provide the mechanism for the DCC mediated coupling ofA and B to give C, and show how N- hydroxybenzotriazole accelerates the reaction (10) O 0 COOH ®fl0 @ w; m R1 A NH + /i\ -————* 7r/< R 2 R1 B NHBoc R C (D NHBOC N D00 0 Q: “N N—hydroxybenzotriazole N=C=N N CH Chemistry 302 winter, page 6 6. Provide intermediates and detailed mechanisms of all reactions necessary to carry out the Strecker synthesis, as outlined in the scheme (10). (9 G) 0 KCN/NH4 Ci NH2 .493 NH2 H R+H $.- R+H CN COOH R Chemistry 302 winter, page 7 7‘ Provide a detailed mechanism for the following transformations (10) {film CI CHO (3) MeOOC / H3COOC Cl 1 O (4) ch000 COOCHQCH3 / Q0 I I x N V H ,COOCHZCHB COOCHZCH3 l; Oék/ X HZN V X NH3 Chemistry 302 winter, page 8 8. Lysine is an Important constituent of the aldoiase cataiyzed condensation of acetaldehyde with glyceraldehyde 3—phosphate to give D-2—deoxyribose 5—phosphate. Provide intermediates and reasonable mechanisms for the transformations.(10) M's - 2 v P i O M. o OH 03 O O / + i + [inflow—)2 K ? 72 _, OH .1 \ 3 H CH3 —*— 0P03 NHz OH OH Chemistry 302 winter, page 9 9 Outline a synthesis of stanozolol, starting from androsterone (reagents and intermediates only). (10) OH HO“ \’ / [fiftiij androsterone stanozoiol Chemistry 302 winter, page 10 10. Reaction ofA and B with sodium ethoxide in ethanol gives C, the product of kinetic control D, and the final stable compound E. Provide mechanisms and missing intermediates. No resonance structures of intermediate carbanions necessary, 0 o , 4 f4 (3) t ) O ””“ o¢ ‘v/ 0 o A B C / \ (3) O O E ...
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This note was uploaded on 03/06/2012 for the course CHEM 302 taught by Professor Sleiman during the Winter '12 term at McGill.

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Chem_302_april2005 - FACULTY OF SCIENCE FINAL EXAMINATION CHEMISTRY 180~302.01(winter Organic Chemistry Ill Examiners G Just Monday N Moitessier

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