Regioselective hydrosilylation of terminal alkynes using pentamethylcyclopentadienyl iridium(III) metallacycle catalysts

Abstract

Pentamethylcyclopentadienyl iridium(III) metallacycles catalyse the hydrosilylation of alkynes using triethylsilane and no additive. The reactions proceed rapidly and efficiently at low catalyst loadings and under mild reaction conditions. If catalyses starting from terminal alkynes lead selectively to (Z)-alkenylsilanes in high yields, reactions are less efficient and selective starting from internal alkynes due to steric hindrance and the possible formation of isoquinolinium salts. Mass spectrometry highlights up to two consecutive 1,2-insertions of alkynes could take place into the catalyst iridium-carbon bond.