Regio- and steroselective cross-metathesis of silylacetylenes with terminal olefins and α,ω-dienes

• Silylacetylenes undergo stereoselective cross-metathesis with 1-alkenes and α,ω-dienes.
• Silylated dienes and trienes can be selectively formed with yields up to 75%.
• [RuCl2(H2IMes)(PCy3)2(CHPh)] activated with HCl/Et2O is efficient catalyst of the process.

Second generation Grubbs catalyst [RuCl2(H2IMes)(PCy3)(CHPh)] initiates regio- and stereoselective cross-metathesis of silylacetylenes with 1-alkenes and α,ω-dienes leading to the formation of E-2-silyl-1,3-dienes and E-2-silyl-1,3,n-trienes, respectively. Efficient progress of the reaction is achieved by using 5–8 mol% of the benzylidene initiator and twofold excess of olefin (with respect to silylacetylene) as well as ethereal solution of HCl (10–20 mol% with respect to the catalyst) as an activator. The reaction is proposed to be catalysed by alkylidene complex [RuCl2(H2IMes)(PCy3)(CHR)] (where R = alkyl, n-alkenyl) generated from the benzylidene initiator, and proceed via initial interaction of a metal alkylidene with a triple bond.

Silylacetylenes undergo regio- and stereoselective cross-metathesis with 1-alkenes and α,ω-dienes in the presence of the second generation Grubbs catalyst.Figure optionsDownload as PowerPoint slide