Synthesis of novel chiral biquinolyl diphosphine ligand and its applications in palladium-catalyzed asymmetric allylic substitution reactions

Abstract

A novel chiral diphosphine ligand, 6,6′-bis(diphenylphosphino)-5,5′-biquinoline (BIQAP) was synthesized via two step reactions using optical pure BIQOL as starting material and the molecular structure of (R)-BIQAP was determined by single-crystal X-ray diffraction. The ligand was used for Pd-catalyzed asymmetric allylic substitution reactions. High enantioselectiveties were obtained in the corresponding C–C and C–N bond formation of 1,3-diphenyl-2-propenyl acetate, with dimethyl malonate (up to 94% ee) and with potassium phthalimide (up to 96% ee).