Asymmetric 1,4-conjugation addition of diethylzinc to cyclic enones catalyzed by a self-assembled copper complex

A new self-assembled catalyst system based on copper complex was developed for the 1,4-conjugation addition of diethyl zinc to cyclic enones. The self-assembled catalyst was readily prepared from (R)-[1,1']binaphthalenyl-2,2'-diamine (1 a), (L)-tryptophan (3f) and copper(I) chloride (CuCl). Several enones were found to be suitable substrates in the presence of the self-assembled copper catalyst [10 mol% (R)-1a, 10 mol% (L)-3f and 10 mol% CuCl] under optimized conditions. The desired products were afforded with high isolated yields (up to 98%) and moderate to good enantioselectivities (up to 80% ee) in mild conditions (at 0 degrees C). Copyright (C) 2009 John Wiley & Sons, Ltd.