Synthesis of novel N,P chiral ligands for palladium-catalyzed asymmetric allylations: the effect of binaphthyl backbone an the enantioselectivity

A series of novel chiral aminophosphine ligands with a 5,5,6,6',7,7',8,8'-octalhydro-1,1'-binaphthyl backbone (H-8-MAPs) have been synthesized. The application of these ligands in asymmetric allylic substitutions was examined and higher enantioselectivity was observed than that by using the parent ligand (MAP). Under the optimized conditions, the allylation product can be obtained in up to 90.9% ee with H-8-MAP having 3,5-xylyls as chiral inducer. The dramatic effect of the binaphthyl backbone on the enantioselectivity of the reaction can be attributed to the change of the bite angle in H-8-MAPs/Pd complexes. (C) 2000 Elsevier Science Ltd. All rights reserved.