Yinhua Huang

Direct Synthesis of Chiral Tertiary Diphosphines via Pd(II)-Catalyzed Asymmetric Hydrophosphination of Dienones

A highly diastereo- and enantioselective Pd(II)-catalyzed hydrophosphination of dienones with Ph(2)PH involving formation of double C*-P bonds has been developed, providing a series of chiral tertiary diphosphines (chiral PCP pincer ligands) in high yields. A catalytic cycle for the reaction was proposed.

Asymmetric Synthesis of Triarylmethanes by Rhodium-Catalyzed Enantioselective Arylation of Diarylmethylamines with Arylboroxines

The reaction of racemic diarylmethylamines, (Ar(1)Ar(2)CHNR2), where Ar(1) is substituted with a 2-hydroxy group, with arylboroxines (Ar(3)BO)3 in the presence of a chiral diene-rhodium catalyst gave high yields of chiral triarylmethanes (Ar(1)Ar(2)CH*Ar(3)) with high enantioselectivity (up to 97% ee). The reaction is assumed to proceed through o-quinone methide intermediates which undergo Rh-catalyzed asymmetric 1,4-addition of the arylboron reagents.

Palladacycle-Catalyzed Asymmetric Hydrophosphination of Enones for Synthesis of C*- and P*-Chiral Tertiary Phosphines

A highly reactive and stereoselective hydrophosphination of enones catalyzed by palladacycles for the synthesis of C*- and P*-chiral tertiary phosphines has been developed. When Ph(2)PH was employed as the hydrophosphinating reagent, a series of C*-chiral tertiary phosphines were synthesized (C*-P bond formation) in high yields with excellent enantioselectivities, and a single recrystallization provides access to their enantiomerically pure forms. When racemic secondary phosphines rac-R(3)(R(4))PH were utilized, a series of tertiary phosphines containing both C*- and P*-chiral centers were generated (C*-P* bond formation) in high yields with good diastereo- and enantioselectivities. The stereoelectronic factors involved in the catalytic cycle have been revealed.

Asymmetric synthesis of P-stereogenic diarylphosphinites by palladium-catalyzed enantioselective addition of diarylphosphines to benzoquinones.

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 °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.

Asymmetric Synthesis of Enaminophosphines via Palladacycle-Catalyzed Addition of Ph2PH to α,β-Unsaturated Imines

A highly reactive, chemo- and enantioselective addition of diphenylphosphine to α,β-unsaturated imines catalyzed by a palladacycle has been developed, thus providing the access to a series of chiral tertiary enaminophosphines in high yields. A putative catalytic cycle has also been proposed.

Rhodium-Catalyzed Asymmetric Arylation/Defluorination of 1-(Trifluoromethyl)alkenes Forming Enantioenriched 1,1-Difluoroalkenes

The reaction of 1-(trifluoromethyl)alkenes (CF3CH=CHR) with arylboroxines (ArBO)3 in the presence of a chiral diene-rhodium catalyst gave high yields of chiral 1,1-difluoroalkenes (CF2=CHC*HArR) with high enantioselectivity (≥95% ee). The reaction is assumed to proceed through β-fluoride elimination of a β,β,β-trifluoroalkylrhodium intermediate that is generated by arylrhodation of the 1-(trifluoromethyl)alkene.

Palladacycle catalyzed asymmetric P-H addition of diarylphosphines to N-enoyl phthalimides.

The first asymmetric phospha-Michael addition of diarylphosphines to N-enoyl phthalimides has been developed in the presence of a chiral palladacycle catalyst. A library of free chiral tertiary phosphine adducts were directly obtained with excellent yields and enantioselectivities. Products can be subsequently functionalized to afford β-phosphinoamides, the direct preparation of which from cinnamides has been notoriously challenging.