Pd-catalyzed asymmetric allylic alkylation using furanoside diphosphinite ligands

摘要

We have tested furanoside diphosphinite ligands 7 and 8, derived from inexpensive D-(+)-xylose, in the Pd-catalyzed allylic alkylation of two substrates with different steric properties. Enantiomeric excesses of up to 31% with good activities were obtained in the Pd-catalyzed allylic alkylation of substrate rac-1,3-diphenyl-3-acetoxyprop-1-ene 9 with dimethylmalonate as nucleophile. Our results show that the absolute configuration at carbon C-3 of the carbohydrate backbone controlled the sense of enantioselectivity. Models for asymmetric induction are discussed based on the absolute stereochemistry of the product. (c) 2005 Elsevier B.V. All rights reserved.