CHEM_302_april2007

CHEM_302_april2007 - FACULTY OF SCIENCE FINAL EXAMINATION...

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Unformatted text preview: FACULTY OF SCIENCE FINAL EXAMINATION CHEMISTRY 302, 200701 Examiners: G. Just Tuesday, April 17, 2007 N.Moitessier 9.00 - 12.00 AM Student Name Student Number There are 20 questions in this final examination. Answer them on the space provided. The first 7 question (part 1) worth 35% correspond to class test 1. Write it only if you wish to improve your final mark. Questions 8-14 (part 2) worth 35% correspond to class test 2. Write it only if you wish to improve your final mark. Questions 15-20 (part 3) worth 30% should be written by all students. If you have written a part twice, the better version willbe used to make up your final grade. No dictionaries, calculators etc are allowed. 7390514 770” D/cflm Mm: me ,Mwa) Chem 302.200701, page 1 PART 1 Question 1.(5) Threose and erythrose are tetroses having formula C4H804. 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 trisaccharide GalBl —>4GalNAcB1——> 6Ga1 ~ (Gal =galactose, the 4-epimer of glucose, GalNac = 2-deoxy-2-N-acetylaminogalactose) Chem 302.200701, page 2 3. Provide a detailed mechanism for the following transformation (5) H l H OCHS H OCH3 Question 4.(5) Give reagents, intermediates and mechanisms for the following transformation 0 0 HM I HNJT 92/73»: A T O - . O N ’ ———-—' HO . O —h- ,___.. O HOH H H N3 3'-azido-3'-deoxy- 5'-tritylthymidine thymidine Chem 302.200701, page 3 5. Provide mechanisms for the following ammonia mediated deprotections (5) 6. Provide a detailed mechanism for the following transformation (one acetylation only) (5) H 0A0 HOH ' . . . ‘ HO AczOlpyrldIne H 0 H91 OH A3930 H H H H Ac“ DEG-i3 o Chem 302.200701, page 4 7. Provide a detailed mechanism for the following transformation (no resonance structures necessary)(5) Dmno O B HO O a NH2 NH2 CIJ \ N of? / \ N DMTR= dimethoxytrityl / __.. p P\ "§ I \ /§ 0.: 8 ° O OH OH PART 2 (corresponds to class test 2) 8) Provide reagents and mechanisms for the following deprotection step used in peptide synthesis.(5) O. O—n’ ~R O R-NH2 Chem 302.200701, page 5 9) Provide reagents and mechanisms for the following deprotection step used in peptide synthesis.(5) H 0—H/ ‘R 2 O 10_. Provide intermediatesqand detailed mechanisms for the following transformation (5) GD E) O KCNINH4 Cl NH2 H R—|—H CN R 11. Provide intermediates and detailed mechanisms for the following transformation (5) NH2 HG) NH2 R—l— '—_.» R—l—H H . CN water COOH Chem 302.200701, page 6 12. in the following transformation, the two pro-R hydrogens at C-2 and C-3 of 1 are transferred to the appropriate receptors to form 2. Label the two hydrogens as pro-R, and complete the equations by entering the missing arrows, protons etc (5) FAD W?” FADHZ «w H H30 N ,NYO H38 N NYC) U / NH m I NH H30 N H C N O H O O H," H 0 RNSCOA RN80“ 1H‘H 2 13 Label the 2 hydrogens shown on 0-2 in 2 as pro-R or pro-S, and indicate if the reduction of 1 to 2 occured by a re or si face attack (5). O O NADPH HO OH O MSACP MSACP Acetoacetyl ACP H H 2 1 14. Draw the structures of estradiol, testosterone, progesterone and cholesterol (5) Chem 302.200701, page 7 PART3 15. One of the products isolated in the reaction of 3-ethylindole with methyl iodide is 2-ethyl-3-methylindole. provide a mechanism to explain the results.(5) CHy —> \ \ N H 12 16. A protein-bound lysine reacts with 5-amino-4-oxopentanoic acid (1) to provide a precursor (2) for the biosynthesis of porphyrinsDraw the appropriate enamine and imonium salt of 1, and show how they react to provide 2 (5) e 6 ‘COO 6 C00 C00 H N L s-NH O I', _ H 1 —’ '45 HZN 2 lfiN Chem 302.200701, page 8 17. 1 and 2 react in ethanolic sodium ethoxide to provide a product of Michael addition (1 ,4—addition), which then further reacts to provide the product of kinetic control 3. Provide the structure of the intermediate, and simplified mechanisms for these reactions (5). (t 0 e (9 H30 £0142 EtO Na 0 ——F'“ Gift 0 CH3 H‘O 1 2 3 18. Provide a detailed mechanism for the following transformatbn (5) or Cl CHO MeOOC / H3COOC EtOH 1L pH=8.5 o o Chem 302.200701, page 9 19. How would you perform the following transformation (include simplified mechanisms) (5) 20. How would you perform the following transformation (include detailed mechanisms) (5) O 9H3 o EH3 HO N\ HZN | \ | —* / N / N 02N ...
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CHEM_302_april2007 - FACULTY OF SCIENCE FINAL EXAMINATION...

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