Ex02anss2012

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Unformatted text preview: optical rotation measured by a polarimeter. OH O OH HO OH Cl Cl O O CH3 O N OH HO HO H O CH3 O (f) (6 pts) The alkene (Z)-2-hexene adds Br2 to give (circle ONE)— (1) (2S,3R)-2,3-dibromohexane (2) equal amounts of (2S,3R)-2,3-dibromohexane and (2R,3S)-2,3-dibromohexane (3) mostly (2R,3R)-2,3-dibromohexane (4) mostly (2S,3S)-2,3-dibromohexane (5) equal amounts of (2S,3S)-2,3-dibromohexane and (2R,3R)-2,3-dibromohexane (6) a meso compound Comment: Draw the alkene, carry out an anti-addition, and see what you get. Because the starting materials are achiral, we must get the racemate of a chiral product. 3. (19 points) Provide the missing structures in the boxes. (a) (4 pts) Complete the following reaction by providing a starting material with formula C10H16 that can give only the product shown at the right. MCMP 204 / Exam 2 / Spring 2012 ANSWERS Page 3 O HC + CCH2CH2 H2O H3O+ H3C C CH2CH2 (b) (3 pts) Provide the missing product. OH Me + H2O H3 O+ Me (c) (3 pts) Provide the missing product. + HBr peroxides Br (d) (3 pts) Draw the carbon-containing free-radical intermediate in reaction (c). Br (e) (6 pts) In the boxes, draw the structures of three enols that would be spontaneously converted into the following ketone. (Don’t forget stereoisomers.) O H3C OH H2C 4. CCH2CH2CH3 HO Me C CH2CH2CH3 H Me H HO (12 points) Glutathione is a tripeptide of glutamic acid, cysteine and glycine that contains an unusual peptide bond linkage between the carboxylic acid side chain of glutamic acid and the alpha amino group of cysteine (forming the amide bond circled below). In biology, glutathione in cells protects against oxidative damage. Because the linkage between glutamic acid and cysteine is unusual, cells must manufacture glutathione using a separate enzymatic pathway (rather than the typical ribosomal pathway used for other polypeptide and protein syntheses). MCMP 204 / Exam 2 / Spring 2012 ANSWERS 4 Page O HS O H2N O H N HOOC OH O H2N OH COOH N H H2N SH NH2 O O glutathione OH OH glycine cysteine glutamic acid individual amino acids: (a) (3 pts) Explain briefly why the circled peptide bond considered “unusual.” The peptide bond is bet...
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This note was uploaded on 06/18/2012 for the course MCMP 204 taught by Professor Berkstrom during the Spring '08 term at Purdue University-West Lafayette.

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