Exam 2 -- Fall 2008 -- Blank

Exam 2 -- Fall 2008 -- Blank - I. (26 points) A. Vincamine...

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Name _____________________ Page 1 I. (26 points) A. Vincamine is an alkaloid natural product that is used as a nootropic agent (a class of drugs that treat impaired cognitive abilities) to combat the effects of aging. It acts as a vasodilator, and increases blood flow to the brain. The structure of vincamine is provided below. (a) Circle all of the tetrahedral carbon stereocenters and clearly assign the stereochemical configuration for each stereocenter ( R or S ). N N H O O H 3 C OH Vincamine 9 (b) Check the boxes next to all (c) Draw the enantiomer of vincamine true statements about vincamine: Vincamine Is a chiral molecule. Has a chiral enantiomer. Has one meso stereoisomer. Has an achiral diastereomer. Has six chiral diastereomers. Is not optically active. 3 5 B. Using lines, dashes, and wedges to indicate stereochemistry when appropriate, draw the structure of ( E )-(2 S ,6 R )-6-bromo-5,5-diethyl-1-iodo-7-methyloct-3-en-2-ol. 9
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Name _____________________ Page 2 O CH 3 O 2 N H 3 C H 3 CO OSi(CH 3 ) 3 A H H H K eq <1 =1 >1 K eq circle one answer in the box above 14 (b) How many signals (peaks) will appear in the 13 C NMR spectrum of A? 3 B . For each of the pairs of molecules drawn below, place letters in the corner boxes corresponding to all accurate descriptions of the relationship between the two molecules. A enantiomers B diastereomers C different conformations of the same molecule D identical conformations of the same molecule E constitutional isomers F stereoisomers G different molecules H both are optically active I neither is optically active (a) H 3 C CH 3 HO Br H HO CH 3 Br CH 3 H all letters that apply 4 (b) 4 N H N H Br Br Br Br (c) O O OH H O O OH H 4 H H II. (29 points) A. Six-membered oxygen heterocycles are found in a wide range of
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This note was uploaded on 01/30/2011 for the course CHEM 210 taught by Professor Capolla during the Spring '07 term at University of Michigan.

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Exam 2 -- Fall 2008 -- Blank - I. (26 points) A. Vincamine...

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