Ru(0)-Catalyzed Straightforward Synthesis of Conjugated Tetraenes: An Approach using Two Internal Alkynes with 1,3-Butadiene

Abstract

The Ru(0)-catalyzed straightforward synthesis of conjugated tetraenes has been achieved in up to 85% yield by coupling of 2 equiv of internal alkynes with 1,3-butadiene at room temperature. The stoichiometric reaction of [Ru(η 4 - cisoid -1,3-butadiene)(η 4 -1,5-COD)(NCMe)] with 2 equiv of 3-hexyne produces a tetraene complex of Ru(0), [Ru{3–6-η 4 -(3 E,5 E,7 E,9 E )-4,9-diethyldodeca-3,5,7,9-tetraene}(η 4 -1,5-COD)(NCMe)], in 98% yield, which releases the conjugated tetraene ligand in 92% yield by exposure to 1,3-butadiene.