Winter 2008 KEY-4 - Name:_KEY_ Page 1(W.08.215.E3p1) I. (...

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Name:______KEY_______________ Page 1(W.08.215.E3p1) JOC , 2008 , 73, 1234 OH H OH OCH 2 Ph H O H NO 2 PhS PhS b) Draw a Fischer Projection of the open chain form of Molecule F: PhCH 2 O CH H OH PhCH 2 O CH 2 OCH 2 Ph H OH H CH(SPh) 2 CH 2 NO 2 O a) How many stereoisomers would Molecule F have (not including F itself)? Molecule F c) ( , 2008 , 73 , 1379) Label the stereocenters in the following ribo- phytophingosine. ( Circle R or S ) I. ( 25 points) H NH 2 OH C 13 H 27 OH R or S R or S R or S e) How many epimers does D- allose have which are also D- aldohexoses? f) How many epimers does D- allose have which are L- aldohexoses? 31 3 1 ( JACS , 2007 , 129 , 9885) Lowary synthesized an oligosaccharide that tuberculosis bacteria include in their cell walls. The oligosaccharide includes 22 D-arabinofuranose residues, four of these are ! -arabinofuranosides, ! -linked sugars that are hard to introduce in a stereocontrolled manner. The others are linked via " (1 -> 5), " (1 -> 3), and ! (1-> 5) linkages. Arabinose is (2S,3R,4R)-2,3,4,5-tetrahydroxypentanal. g) Draw the Fischer projection of D-arabinose h) Draw the Haworth projection of ! -D-arabinofuranose d) A stamp commemorating sugar chemist and Nobel Laureate Gerty Cori featured an incorrect chemical structure. Draw the correct chair structure of " -(D)-glucopyranose-1-phosphate. (The molecule will have a -2 charge.) O H HO H HO H O OH H H OH P O O - - O CHO HO H H OH CH 2 OH H OH H OH H CH 2 OH OH H H OH O i) Draw a disaccharide of "# D-arabinofuranose with an " (1 -> 5) linkage O H H CH 2 OH OH H H OH O OH H H CH 2 OH H H OH O 2 3 2 2 4 3 3 3 3 H
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Name:______KEY_______________ Page 2(W.08.215.E3p2) b) JOC , 2008 , 73, 661 CH 2 NH 2 OH H H HO OH H OH H CH 2 OH O H CH 2 N OH H H HO OH H OH H CH 2 OH H O O O O O O 1) NaOH 2) protonation O O O O O excess NaH CH 2
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Winter 2008 KEY-4 - Name:_KEY_ Page 1(W.08.215.E3p1) I. (...

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