Novel 1,3-diene synthesis from alkyne and ethylene by ruthenium-catalyzed enyne metathesis

A novel 1,3-diene synthetic method from alkyne and ethylene was developed u sing ruthenium-catalyzed enyne metathesis. The reaction procedure is very s imple: A CH2Cl2 solution of alkyne was stirred at room temperature under et hylene gas (1 atm.) in the presence of a catalytic amount of ruthenium benz ylidene complex. The yield was good and the conversion yield was high. Dien es having functional groups such as a keto-carbonyl group, silyloxy group, ester, and ketal were synthesized from the corresponding alkynes and ethyle ne. In this reaction, the alkyne having a hetero atom at the propargylic po sition gave a good result and ether oxygen or amine nitrogen that coordinat e strongly to the ruthenium catalyst prevents the reaction. (C) 1999 Elsevi er Science Ltd. All rights reserved.