Selective Dimerisation and Addition of Carboxylic Acids to Terminal Alkynes, Catalysed by Thermolysed Grubbs’ Catalyst: A Novel Synthesis of Enynes and Vinyl Esters

Abstract

The transformation of triple bonds of terminal alkynes was carried out at 110 °C in the presence of the thermolysed RuII-alkylidene [Cl2(PCy3)2Ru=CHPh]. The transformation of phenylacetylene is strongly pKa-dependent, the preference switching from vinylation to dimerisation at increasing pKa values. Aliphatic alkynes only give rise to vinylation adducts, with a regioselectivity for Markovnikov addition. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)