On the Alkylation of Ph 3 PCHP(O)Ph 2 : Formation and Crystal Structures of Neutral and Cationic Addition Compounds

Ylide Ph 3 PCHP(O)Ph 2 ( 1 ) is the hydrolysis product of carbone C(PPh 3 ) 2 and reacts with MeI to produce the corresponding salt [Ph 3 PCH(Me)P(O)Ph 2 ]I ( 2 ). Deprotonation of the cation of 2 with K[N(SiMe 3 ) 2 ] in methyl cyclohexane or toluene gives neutral ylide Ph 3 PCMeP(O)Ph 2 ( 7 ). Addition of AlBr 3 at the oxygen atom of 7 involves simultaneous uptake of a proton along with formation of [Ph 3 PCH(Me)P(OAlBr 3 )Ph 2 ][AlBr 4 ] ( 9 ). Small amounts of resultant proton bridged [H{Ph 2 (O)PCH(Me)PPh 3 } 2 ][I 3 ] 3 ( 10 ) were isolated during attempts to silylate 2 with trimethylsilytriflate; the main product was found to be [Ph 3 PCH(Me)P(O)Ph 2 ](O 3 SCF 3 ) ( 8 ). In the course of our studies several by‐products with cation [Ph 3 PCH 2 P(O)Ph 2 ] + ( 4 to 6 ) were obtained. All compounds were characterized by multiple NMR and X‐ray analyses.