Pentanidium-catalyzed enantioselective phase-transfer conjugate addition reactions

J Am Chem Soc. 2011 Mar 9;133(9):2828-31. doi: 10.1021/ja1098353. Epub 2011 Feb 11.

Abstract

A new chiral entity, pentanidium, has been shown to be an excellent chiral phase-transfer catalyst. The enantioselective Michael addition reactions of tert-butyl glycinate-benzophenone Schiff base with various α,β-unsaturated acceptors provide adducts with high enantioselectivities. A successful gram-scale experiment at a low catalyst loading of 0.05 mol % indicates the potential for practical applications of this methodology. Phosphoglycine ester analogues can also be utilized as the Michael donor, affording enantioenriched α-aminophosphonic acid derivatives and phosphonic analogues of (S)-proline.