Oxaphosphetane versus betaine formation in epoxide ring opening by PPh3: a mechanistic probe by ab initio and DFT modeling

Ab initio and density functional investigations on the deoxygenation of cis-2,3-dimethylepoxide by PPh3 reveals a two-step mechanism. Simultaneous ring opening and C-C bond rotation results in oxaphosphetane formation, rules out a betaine intermediate and is consistent with the inversion of stereochemistry.