CHEM_302_december2006

CHEM_302_december2006 - FACULTY OF SCIENCE FINAL...

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Unformatted text preview: FACULTY OF SCIENCE FINAL EXAMINATION CHEMISTRY 302 200609 Organic Chemistry lll Examiners: G. Just Monday, December 7, 2006 N. Moitessier 14.00-17.00 Student name: Student number: There are 15 questions in this exam. Write your answers in the space provided. Questions 1-5, worth 35% and corresponding to the first class test, may be rewritten, if you wish to improve your mark. Same for questions 6-12, worth 35%, corresponding to the second class test, and question 13, worth 10%, corresponding to the third class test. If you rewrite, the higher mark will be used to calculate the final mark. Questions 14-15, worth 20%, have to be written by all students. No models, computers, notes etc. Chem 302.200609, page 1 Question 1.(5) Threose and erythrose are tetroses havin'g formula C4H304. Sodium borohydride reduction of threose gives a butane-1,2,3.4-tetraol which rotates plane-polarized light, and does not have a plane of symmetry. Sodium borohydride reduction of erythrose gives a butane-1,2,3,4—tetraol which does not rotate plane-polarized light, and does have a plane of symmetry. Draw the Fischer projections of D-threose, and of L-erythrose. Question 2.(5) Draw the conformation of the following disaccharide Galocl —>4Ga1NAc[31 (Gal =galactose, the 4-epimer of glucose, GalNac = 2—deoxy-2-N-acetylaminogalactose) Chemistry 302.200609, page 2 3. 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. (10) 0A HOH OH H C H Tro H HO HO 4H A00 0 H 4. HO 0 Ho . 0 HO A00 A00 H —~ ,0 HO OH O /O H H H ,0 A H H H AC; Br H C 0_CH3 1 2 Cellobiose 0 Chem 302.200609, page 3 HN 4. How would you prepare AZT (3'-deoxy-3'— ¢J\ I azidothymidine) fi‘om thymidine (5) H O O N O H OH H thymidine 5. Provide intermediates and mechanisms for the following biosynthetic transformations (10) O3P“O OH OH NHAc = DH 6 .o = ,o—( e OsP-O -‘ 0 COO HO + O P COO AcHN HO H 3 phosphoenol- H0 0—H ruvate PEP py ( _) NeusAc-Q-P Man NAc-6—P Chem 302.200609, page 4 PART 2 (corresponds to class test 2) 69 6. In the transformation shown, H2 is transferred from aspartate to NAD. Label H1 and H2 in NADH as pro-R or pro-S, and indicate if the H2 transfer occured on the si or re face of NAD©(5) (9 NAD NADH W N I; CONHZ 6 H1 "meow—2006) WE) 000 e M (9 e (9 00C NH; 7. Provide products and the mechanism for all the steps in the following transformation. (5) H\ ‘FHS 0 H6) H—p—g—O—(NHR RNHZ H CH3 8. Reaction of 2R-bromopropionic acid with aqueous sodium hydroxide gives 2-hydroxypropionic acid. What is the stereochemistry of the product? Outline the mechanism of the transformation. (5) Chem 302.200609, page 5 9. Provide detailed mechanisms for the following transformations. (5) 66) - 69 03530 Ospo R ,Lys R I\ \E + A e |\ “lg/#008 + HZN’LyS M35 / 0’ H2N 000 Kg / oJ—i CH3 CH3 enzyme-bound _ . . . . pr imine PLP amino acrd Imlne 10. Provide detailed mechanisms for the following transformations. (5) "DO 00. - R 3 i _. / e I \ \HJFCOS I \ 1;! COO erg / o”H H’as / 0’H CH3 CH3 PLP-amino acid imine oc—keto acid imine Chem 302.200609, page 6 11. Provide detailed mechanisms for the following transformations. (5) ee (96 Capo R 0390 R / (a e I \ Iii/kooo “20 l \‘ 5H2 + oékcoo - , ,H WEB / 0’H H 5 / 0 CH3 CH3 a—keto aCid imine pyridoxamine oc— ketoacid phosphate (PMP) 12. Provide a detailed mechanism for the following transformation(5) O O o O O GOACJKSACP + H3CJJ\S-Synthase. MSACP H2 Acetoacetyl ACP Malonyl ACP Acetyl synthase Chem 302.200609, page 7 PART 3 (corresponds to class test 3) 13. The following is an outline of the synthesis of clopirac. Fill in reagents. and outline all mechanisms. (10) (+3 /\ ifNMe I NM N N N fig ( = iodide) © Cl C! ~——-—|- CI Ci CI Chem 302.200609, page 8 PART 4 (has to be written by everybody) 14. Provide mechanisms for the following reactions a,b,c,d,e used in the synthesis of Viagra.(10) o H 0 CH3 0 CH3 N :11 R1 EtO I \ a) (MeO)2SC}2 Ho I \ c)HN03iHZSO4 H0 I \ /N b)NaOH /N ON ’7“ o 9H3 N d) 30012 /N OZN e) NH4OH Chem 302.200609, page 9 15. Outline a synthesis of stanozolol, starting from androsterone acetate (reagents and mechanisms) (10) d t ceta e stanozolol, an anabolic steroid a” ms emne a t Clinton et ai, J. Am. Chem. Soc 1959. 81,1513-1514. ...
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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_december2006 - FACULTY OF SCIENCE FINAL...

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