PD-CATALYZED ASYMMETRIC ALLYLIC ALKYLATIONS USING VARIOUS DIPHENYLPHOSPHINO(OXAZOLINYL)FERROCENE LIGANDS

Abstract

Pd-Catalyzed asymmetric allylic alkylations have been studied using a series of chiral diphenylphosphino(oxazolinyl)ferrocene ligands 4-8. With these ligands, up to 99% and 63% ee are obtained for rac-(E)-1,3-diphenylprop-2-enyl-1-acetate and rac-(E)-1,3-dimethylprop-2-enyl-1-acetate, respectively, with dimethyl malonate as the nucleophile. Some of the ligands 4-6 generate corresponding Pd-catalysts more reactive than those formed from other known ligands. A noticeable influence of the planar chirality on the enantioselectivity is observed. Different coordination modes can be suggested for the distinguishable enantioselectivity and reactivity patterns observed in the reactions with the ligands 4-8. (C) 1997 Elsevier Science Ltd.