Electron-Poor Chiral Diphosphine Ligands: High Performance for Rh-Catalyzed Asymmetric 1,4-Addition of Arylboronic Acids at Room Temperature

Abstract

Electron-poor chiral diphosphine ligands, MeO-F(28)-BIPHEP (1a) and MeO-F(12)-BIPHEP (1b), were synthesized for controlling a transition-metal catalyst electronically. The 1b-ligated Rh catalyst showed excellent catalytic activity with high % ee for asymmetric 1,4-addition of arylboronic acids to alpha,beta-unsaturated carbonyls at 20 degrees C. The strong pi-acceptor ability of 1b induces transmetalation of arylboronic acid to catalyst precursor [RhCl(1b)](2) directly in the first step of the catalytic cycle.