Asymmetric Synthesis of P-Stereogenic Diarylphosphinites by Palladium-Catalyzed Enantioselective Addition of Diarylphosphines to Benzoquinones
摘要:
The reaction of phenyl(2,4,6-trimethylphenyl)phosphine with a substituted benzoquinone in the presence of a chiral phosphapalladacycle complex as a catalyst and triethylamine in chloroform at -45 degrees C proceeded in a new type of addition manner to give a high yield of a 4-hydroxyphenyl phenyl(2,4,6-trimethylphenyl)phosphinite with 98% enantioselectivity, which is a versatile intermediate readily convertible into various phosphines and their derivatives with high enantiomeric purity.
A copper(I)-catalyzed asymmetric synthesis of P-chiral aminophosphinites with esters of hydroxylamines is achieved by means of the dynamic kinetic transformation of unsymmetrical diarylphosphines. A two-electron redox process is proposed for this reaction based on mechanistic studies.