デオキシスタニル化によるオレフィン形成反応

Abstract

Radical hydrostannylation of propargylic alcohols gives stannylated allylic alcohols regio- and stereoselectively, and subsequent β-elimination of stannyl alcohols (deoxystannylation) gives allenes in a one-pot process. Deoxystannylation proceeds in an anti-fashion by treatment with methanesulfonyl chloride and triethylamine at or below room temperature. Epoxidation or cyclopropanation of a chiral stannylated allylic alcohol and subsequent deoxystannylation affords a chiral allene oxide or alkylidenecyclopropane, respectively. A chiral allene oxide is isolated and characterized for the first time. [3] Cumulenes are synthesized from propargylic alcohols by the stannylation-deoxystannylation sequence. 1, 4-Elimination of stannylated propargylic alcohols as well as 1, 2-elimination of stannylated allenyl alcohols proceeds effectively to give [3] cumulenes. Deoxystannylation proves to be much more efficient than an analogous silyl counterpart because a vinylic carbon-tin bond is easily cleaved under mild reaction conditions.