CRCU

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

• Articles • Previous Articles     Next Articles

Stereoselectivities in α- and β-Amino Acids Catalyzed Mannich Reactions Involving Cyclohexanone

WANG Ying, FU Ai-ping*, LI Hong-liang, TIAN Feng-hui, YUAN Shu-ping, SI Hong-zong, DUAN Yun-bo and WANG Zong-hua   

  1. Institute for Computational Science and Engineering, Laboratory of New Fiber Materials and Modern Textile, Growing Base for State Key Laboratory, College of Chemical and Environmental Engineering, Qingdao University, Qingdao 266071, P. R. China
  • Received:2010-11-26 Revised:2011-01-24 Online:2011-07-25 Published:2011-06-29
  • Contact: FU Ai-ping E-mail:faplhl@eyou.com
  • Supported by:

    Supported by the National Natural Science Foundation of China(Nos.20773071, 20901043), the Natural Science Foundation of Shandong Province, China(No.ZR2010BM024) and the Project of Shandong Province Higher Educational Science and Technology Program, China(No.J10LB06).

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Abstract: 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(α-amino acid) and (R)-3-pyrrolidinecarboxylic acid(β-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 α-amino acid catalysts, anti-selectivity for the β-amino acid catalysts). Calculated and observed diastereomeric ratio and enantiomeric excess values are in reasonable agreement.

Key words: Syn- and anti-Mannich reaction, Stereoselectivity, Amino acid, Transition state