Synthesis of Dihydrobenzosiloles and Silacyclopentanes by Double Hydroalumination of Terminal Alkynes

Abstract

AbstractWe have developed an efficient method for the synthesis of 2,3-dihydro-1H-1-benzosiloles in 19% to 90% isolated yield from 1-hydrosilyl-2-ethynylbenzenes by using two equivalents of diisobutylaluminum hydride. The reaction mechanism involves regioselective double hydroalumination of the alkyne moiety followed by cyclization to a 2-alanyldihydrobenzosilole. A silacyclopentane (silolane) was also synthesized in 97% isolated yield from the corresponding 4-silylbut-1-yne under the same reaction conditions. Although the substrate-scope study was conducted on a 0.5-mmol scale, a gram-scale reaction of (2-ethynylphenyl)(diphenyl)silane under the optimized reaction conditions successfully afforded the desired product in 94% isolated yield without loss of reactivity.