Direct Synthesis of α-Allenols from TMS-Protected Alkynes and Aldehydes Mediated by Tetrabutylammonium Fluoride.

A unique chemoselective synthesis of α-allenic alcohols is presented. Tetrabutylammonium fluoride (TBAF) mediated this transformation under mild reaction conditions. A range of functional groups is well-tolerated in this reaction, while affording adducts in moderate to excellent yields (48-96 %, average 76 %). Mechanistic studies, including the use of tetrabutylammonium hydroxide (TBAH), revealed that the hydroxide ion can be the responsible for the observed rearrangement.