The organocatalyzed domino Michael-aldol reaction revisited. Synthesis of enantioenriched 3-hydroxycyclohexanone derivatives by reaction of enals with alpha,alpha '-diaryl-substituted acetone

摘要

The reaction of enals with alpha,alpha'-diaryl-substituted acetones (pK(a) > 18) catalyzed by (S)-1-(2-pyrrolidinylmethyl) pyrrolidine provides direct access to enantioenriched 2,5,6-trisubstituted-3-hydroxy cyclohexanones. The process constitutes a highly stereoselective organocatalytic tandem Michael-intramolecular aldol reaction. It has been demonstrated that the stereoselection is dependent on the reaction conditions because only syn diastereoisomers are able to cyclize, and that anti diastereoisomers participate in a retro-Michael process decreasing the enantioselection.