Development of New Catalytic Allylation, Aldol Reaction, and Cyanoalkylation

Studies toward General Catalytic Enantioselective Synthesis of Tetrasubstituted Carbons

Abstract

New catalytic methods for allylation, aldol reaction, and cyanoalkylation are described, using copper fluoride as a catalyst and silylated reagents (allyltrimethoxysilanes, ketene silyl acetals, and TMSCH₂CN) as nucleophiles. These reactions proceed under very mild conditions with broad substrate generality. The mechanistic studies suggested that an allylcopper, copper enolates, and copper N-ketene imides, which are generated through dynamic ligand exchange between silicon and copper atoms, are the actual nucleophiles. These reactions can be extended to catalytic enantioselective reactions with ketones using chiral phosphine ligands. Conceptually more advanced direct catalytic cyanoalkylation of aldehydes, using unactivated alkylnitriles as a prenucleophile, is also described.