225Sp04 Test 4 - CHEMISTRY 225 TEST #4 JUNE 11, 2004 1. _...

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CHEMISTRY 225 T E S T # 4 1. ________ (18) JUNE 11, 2004 2. ________ (10) NAME _______________________________________________ 3. ________ (17) G O O D L U C K ! 4. ________ (18) 5. ________ (12) TOTAL (75) 1. (18 Points) CYCLIC STEREOCHEMISTRY. a. ( ________ / 6) Chemists at Michigan State University have developed two microbial syntheses of aminoshikimic acid [ Org. Lett . 2004 , 6 , 1585]. One of these methods involves the amino sugar kanosamine as an intermediate. The structure of kanosamine is shown below. (3) Kanosamine exists as a pair of diastereomers at C(1). Write structures for these two diastereomers that show stereochemistry clearly. (3) Choose one of the two structures you have drawn and convert it to a chair conformation. To help you get started the oxygen and the hydroxymethyl group have already been added. Be sure to indicate which structure you are drawing. O HO H 2 NO H OH kanosamine O OH the diastereomers 1
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2 b. ( ________ / ) 1,2,3-tribomocyclopentane exists in four stereoisomeric forms. Below are planar projections for 1,2,3-tribromocyclopentane. Br Br Br Br Br Br Br Br Br Br AB C D E From this list identify: (2) A pair of enantiomers _________________ (2) All achiral molecules _________________ (2) Two representations of the same stereoisomer ___________________ c. ( ________ / 6) Japanese chemists have recently completed the synthesis of two diastereomeric compounds to serve as models for the CDE/FG rings of prymnesin-1 a toxic agent from algae responsible for massive fish kills worldwide [ Org. Lett . 2004 , 6 , 1501]. The structures of these two diastereomeric molecules ( I and II ) are shown below. O O OO O H H OH H H H CH 3 H H H C D EF G O O O H H H H H 3 H H H C D G I II (3) Directly on the structure of I label all stereogenic carbons with asterisks.
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This note was uploaded on 09/12/2011 for the course NATURAL SC 225 taught by Professor Marician during the Spring '11 term at University of Michigan-Dearborn.

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225Sp04 Test 4 - CHEMISTRY 225 TEST #4 JUNE 11, 2004 1. _...

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