A new chiral 2-sulfonylamino-2'-phosphino-1,1'-binaphthyl ligand for highly enantioselective copper-catalyzed conjugate addition of diethylzinc to benzylideneacetones

摘要

A new axially chiral phosphine-sulfonamide ligand was prepared via a chiral component (R)-2-amino-2'-diphenyl-phosphinyl-l,1'-binaphthyl,which was conveniently synthesized through a new route involving hydrolysis of (R)-2-cyano-2'-phosphinyl-l,1'-binaphthyl followed by Hofmann rearrangement of the amide group.The new ligand was found to be very efficient in copper-catalyzed enantioselective conjugate addition of diethylzinc to acyclic enones such as benzylideneacetones,providing very high enantioselectivity up to 99% ee.