Rearrangement of (Substituted benzyl)trimethylammonium Ylides in a Nonbasic Medium: The Improved Sommelet-Hauser Rearrangement

Article abstract of DOI:10.1021/jo00385a035

Benzyl quaternary ammonium ylide formation in a nonbasic medium was accomplished by fluoride anion induced desilylation of benzyldimethyl<(trimethylsilyl)methyl>ammonium bromide (3a) and ortho- or para-substituted benzyl analogues 3b-k.Treatment of 3 with CsF in HMPA at room temperature gives high yields of the Sommelet-Hauser rearrangement products 7 from 3a and methyl-, acetoxy-, and chloro-substituted analogues 3b-f.However, formation of the Stevens rearrangement products 8 is competitive for the reaction of compounds 3g-k having strong electron-withdrawing substituents such as acetyl, cyano, and nitrogen groups.From the o-cyano-substituted analogue 3h, a considerable amount of para Sommelet-Hauser rearrangement product is isolated.