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

2016-09-14T00:00:00Z (GMT) by Yinhua Huang Tamio Hayashi
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.