Orthopalladated complexes as phase-transfer catalysts for asymmetric alkylation of achiral Schiff base esters

Abstract

The asymmetric C-alkylation of benzophenone Schiff base glycine esters has been achieved using a palladium(II) chiral complex as a phase-transfer catalyst. The aromatic moiety around the metal center and various physicochemical parameters were investigated to study their effect on the asymmetric alkylation reaction under phasetransfer conditions. Moderate enantioselectivity(30-40%) was achieved under room temperature conditions, which is a significant improvement compared to no enantioselectivity with a chiral palladium-salen complex reported earlier. Computer simulation studies indicate that coordination of the metal center with Z-enolate forming a square planar complex provides a favorable steric environment where the a-carbon atom of the enolate is available for enantioselective alkylation.Electronic supplementary material The online version of this article (

Palladium catalysed asymmetric alkylation of benzophenone Schiff base glycine esters in ionic liquids

“…Though acetato-, chloro-and bromo-bridged orthopalladated complexes were prepared and reported in a previous article by us, 28 we have used only the chloro-bridged chiral palladium complexes in the present context. 50% Aqueous potassium hydroxide solution and 1.2 equivalents of the alkylating agent was used in most of the runs under biphasic conditions.…”