Stereoselectivities in alpha- and beta-Amino Acids Catalyzed Mannich Reactions Involving Cyclohexanone

作者：Wang Ying; Fu Ai-ping^*; Li Hong-liang; Tian Feng-hui; Yuan, Shu-ping; Si Hong-zong; Duan Yun-bo; Wang Zong-hua

来源：Chemical Research in Chinese Universities, 2011, 27(4): 673-677.

• Syn- and anti-Mannich reaction
• Stereoselectivity
• Amino acid
• Transition state

The effects of two different amino acid catalysts on the stereoselectivities in the direct Mannich reactions of cyclohexanone, p-anisidine and p-nitrobenzaldehyde were studied with the aid of density functional theory. Transition states of the stereo-determining C C bond-forming step with the addition of enamine intermediate to the imine. for the L-proline(alpha-amino acid) and (R)-3-pyrrolidinecarboxylic acid(beta-amino acid)-catalyzed processes were reported. B3LYP/6-31G** calculations provide a good explanation for the opposite syn vs. anti diastereoselectivities of these two different kinds of catalysts(syn-selectivity for the alpha-amino acid catalysts, anti-selectivity for the beta-amino acid catalysts). Calculated and observed diastereomeric ratio and enantiomeric excess values are in reasonable agreement.

• 出版日期2011-7
• 单位青岛大学