Organocatalysis in synthesis: L-proline as an enantioselective catalyst in the synthesis of pyrans and thiopyrans

Molecules. 2012 Apr 10;17(4):4300-12. doi: 10.3390/molecules17044300.

Abstract

The multicomponent reaction (MCR) of aromatic aldehydes 1 and malononitrile (2) with active methylenes 5a-h in the presence of L-proline produced pyrans and thiopyrans 6a-h stereospecifically and in good yields. Moreover a novel MCR of ethyl propiolate (8) with 1 and 2 in the presence of L-proline to afford (R)-polysubstituted pyran is also reported. X-ray structures, e.e. and optical activity of the synthesized compounds indicated that L-proline as a catalyst is responsible for the observed enantioselectivity in the studied reactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis
  • Crystallography, X-Ray
  • Models, Molecular
  • Nuclear Magnetic Resonance, Biomolecular
  • Proline / chemistry*
  • Pyrans / chemical synthesis*
  • Sulfhydryl Compounds / chemical synthesis*

Substances

  • Pyrans
  • Sulfhydryl Compounds
  • thiopyran
  • Proline