Gas-phase carbanion rearrangements. Does the Wittig rearrangement occur for deprotonated vinyl ethers?

Abstract

Deprotonation of alkyl vinyl ethers (CH₂CHOR) with NH₂^– in the gas phase yields the two carbanions CH₂OR and ^–CHCHOR. The former ion can be synthesized specifically using the S_N2(Si) reaction CH₂C(SiMe₃)OR + NH₂^–→CH₂OR + Me₃SiNH₂: the ion undergoes several competitive and characteristic collision-induced reactions. For example, (i) when R Et, elimination of an alkene, i.e. CH₂OR→(CH₂CHO)^–+(R–H), and (ii) the Wittig rearrangement CH₂OR [graphic omitted] CH₂C(R)O^–.