Reactions of Electrophiles with the Phosphaalkene Mes*PCH₂: Mechanistic Studies of a Catalytic Intramolecular C−H Bond Activation Reaction

A catalytic intramolecular C−H bond activation is reported for the reaction of the phosphaalkene Mes*PCH2 (Mes* = 2,4,6-tri-tert-butylphenyl) with aluminum(III) chloride (0.05, 0.10, and 0.15 equiv). Studies of analogous reactions with gallium(III) chloride and triflic acid facilitated the identification of intermediates, thus providing insight into the reaction mechanism, which involves a phosphenium ion as a fleeting intermediate.