New methods for perfluoroalkylation of carbon-nitrogen double bonds have been developed. Addition of (trifluoromethyl)trimethylsilane (TMSCF3) to alpha,N-diarylnitrones produced a series of alpha-(trifluoromethyl)-N-hydroxyl amines protected as their O-trimethylsilyl derivatives. An alternate procedure using pentafluoroethyllithium (F5C2Li) and chlorotrimethylsilane (TMSCl) afforded O-trimethylsilyl-alpha- (pentafluoroethyl)-N-hydroxyl amines. (C) 1998 Elsevier Science Ltd. All rights reserved.