Base-induced rearrangement of tetraalkyl(diphenylphosphinoyl)hydrazinium salts to phosphinoyl aminals; possible relevance to the photochemical rearrangement of trialkylammonio(diphenylphosphinoyl)imides

Abstract

The phosphinoylhydrazinium salt Ph₂P(O)N(Me)NMe₃I8 has been prepared by methylation of Ph₂P(O)N-NMe₃1. It readily forms the phosphinoyl aminal Ph₂P(O)N(Me)CH₂NMe₂10 on treatment with Bu^tOK at room temperature, presumably by [1,2] sigmatropic rearrangement of the ylide Ph₂P(O)N(Me)N(CH₂)Me₂9. Replacing just one or two Me groups by Et at the ammonium centre of 8 has a rather small effect; the principal product is still a methylene aminal, although a small amount of the ethylidene aminal is also formed. The possible relevance of this [1,2] sigmatropic rearrangement to the mechanism of the photochemical rearrangement of trialkylammonio-N-diphenylphosphinoylimides (phosphinic aminimides) is considered.