FirstP-trifluoromethylated ylides

Abstract

Trifluoromethylated phosphines R2PCF3 (R = NEt2, Me, 1Pr) were methylated by CH4OSO2CF3, yielding the corresponding phosphonium salts [R2P(CF3)CH3] [F3CSO3]. Treatment with LiN(SiMe3)2 at −80°C furnished the phosphorus ylides R2P(CF3) = CH2 that could be trapped by use of hexafluoroacetone with formation of stable 1,2λ5σ5-oxaphosphetanes. The single-crystal X-ray structure determination of one of these oxaphosphetanes showed a distorted trigonal bipyramid at phosphorus with the P-CF3 group in an axial position. © 1996 John Wiley & Sons, Inc.