On the alkylation of Ph3PCHP(O)Ph2: Formation and crystal structures of neutral and cationic addition compounds

Article abstract of DOI:10.1002/ejic.201301427

Ylide Ph₃PCHP(O)Ph₂ (1) is the hydrolysis product of carbone C(PPh₃)₂ and reacts with MeI to produce the corresponding salt [Ph₃PCH(Me)P(O)Ph₂]I (2). Deprotonation of the cation of 2 with K[N(SiMe₃)₂] in methyl cyclohexane or toluene gives neutral ylide Ph₃PCMeP(O)Ph₂ (7). Addition of AlBr₃ at the oxygen atom of 7 involves simultaneous uptake of a proton along with formation of [Ph₃PCH(Me)P(OAlBr ₃)Ph₂][AlBr₄] (9). Small amounts of resultant proton bridged [H{Ph₂(O)PCH(Me)PPh₃}₂][I ₃]₃ (10) were isolated during attempts to silylate 2 with trimethylsilytriflate; the main product was found to be [Ph₃PCH(Me) P(O)Ph₂](O₃SCF₃) (8). In the course of our studies several by-products with cation [Ph₃PCH₂P(O) Ph₂]⁺ (4 to 6) were obtained. All compounds were characterized by multiple NMR and X-ray analyses. New cationic and neutral compounds were obtained by treating phosphonioylide Ph₃PCHP(O)Ph ₂ with MeI. The alkylated product can be deprotonated and gives an addition product with AlBr₃. Product characterizations were carried out using ³¹P NMR spectroscopy and single-crystal X-ray diffraction analyses. Copyright