Cooperative dual catalysis: Application to the highly enantioselective conjugate cyanation of unsaturated imides

Cooperative heterobimetallic catalysis was used as a design principle to achieve a highly reactive system for the enantioselective conjugate addition of cyanide to α,β-unsaturated imides. A dual-catalyst pathway involving chiral (salen)Al complex 1b and chiral (pybox)Er complex 4b provides measurable improvements in rates and enantioselectivities relative to single-catalyst systems. Mechanistic studies point to a cooperative bimetallic mechanism involving activation of the imide by the Al complex and activation of cyanide by the Er complex. Copyright © 2004 American Chemical Society.