Reactions of a Lewis acidic methylene phosphonium cationic adduct with olefins.

Efforts to deprotonate the halophosphonium cations [Ph 2 P(X)Me] + (X = F, Cl) generated species of the form [Ph 2 (X)PC(H)PPh 2 Me][X']. The derivative where X = O 3 SCF 3 provides access to a methylene phosphonium cation. The coordinated triflate anion can be replaced by Et 3 PO and dimethylaminopyridine (DMAP). In addition, the cation reacts with the olefins R 2 CCH 2 (R = Ph, Me) and PhMeCCH 2 . While Ph 2 CCH 2 was shown to give the species [Ph 2 (Ph 2 CCH)PCH 2 PPh 2 Me][O 3 SCF 3 ] 2 with a pendant vinyl group, reactions with methyl substituted olefins undergo additional isomerization to form [Ph 2 (RCH 2 CCH 2 )PCH 2 PPh 2 Me][O 3 SCF 3 ] 2 (R = Ph, Me) featuring pendant allyl moieties.