Synthesis and resolution of 2,2 '-bis[di(p-tolyl)stibano]-1,1 '-binaphthyl (BINASb); the first example of an optically active organoantimony ligand for asymmetric synthesis

摘要

Racemic 2,2'-bis[di(p-tolyl)stibano]-1,1'-binaphthyl (BINASb) (+/-)-2 has been prepared from 2,2'-dibromo-1,1'-binaphthyl 1 via 2,2'-dilithio-1,1'-1,1'-binaphthyl intermediate, and has been resolved via the separation of a mixture of the diastereomeric Pd complexes 4A and 4B, derived from the reaction of (+/-)-2 with di-mu -chlorobis {(S)-2-[1-(dimethylamino)ethyl]phenyl-C,N}dipalladium(II) 3. The optically active BINASbs (S)-(+)-2 and (R)-(-)-2 have been shown to be effective chiral ligands for the rhodium-catalyzed asymmetric hydrosilylation of ketones. (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 31]