S.11.215E2KEYV2 - I(12 points Name Page 1 S.11.215E2 Name...

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Name_____________________________ I. (12 points) Page 1 S.11.215E2
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Name_____________________________ II. (25 points) Page 2 S.11.215E2 O H O NO 2 O OH NO 2 Under ordinary circumstances, we would predict the aldol reaction below to produce 4 different stereoisomers with the formula C 13 H 15 NO 4 . A. Predict the 4 possible products of the reaction and unambiguiously show their stereochemistry. O OH NO 2 O OH NO 2 O OH NO 2 acid catalysis + B. Recently, researchers at the Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional in Mexico studied a way to perform this reaction so that virtually only one stereoisomer was formed. In addition to the advantage of not producing a complicated mixture of stereoisomeric products, the reaction was performed with no solvent. Briefly explain why performing a reaction without solvent would be an important advantage. ( J. Org. Chem ., 76 , 1465.) No solvent = less expensive. Also, no solvent may be "greener". Also could be faster. C. In addition to studying the stereochemistry of this reaction, the researchers also examined the effect of the substitutent on the benzene ring on the yield of the reaction and obtained the following data: O H O X acid catalysis + Product(s) X % yield NO 2 Br Cl H OCH 3 92 90 81 70 62 D. Explain this decreasing trend in percent yield as the substituent X is changed as shown above: As the substituent becomes more electron withdrawing (either through induction, resonance, or both), the carbonyl carbon becomes more electrophilic. or Decreasing electrophilicity of the aldehyde carbonyl carbon may increase the amount of self-
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This note was uploaded on 09/21/2011 for the course CHEM 215 taught by Professor Koreeda during the Spring '07 term at University of Michigan.

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S.11.215E2KEYV2 - I(12 points Name Page 1 S.11.215E2 Name...

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