A new catalytic route for the synthesis of unsaturated organosilicon compounds with vinylic functionality based on cross-metathesis of vinyltrialkoxy- and vinyltris(trimethyl siloxy)-silanes with allyl esters of carboxylic acids catalyzed by ruthenium carbenes (Grubbs catalysts): [Cl-2(PCy3)(2)Ru(=CHPh)] (I), [Cl-2(PCy)(3)(1,3-dimesityl-4,5-dihydroimidazol-2-ylidene)Ru(=CHPh)] (II) is reported. The efficient reaction can be extended to alkyl esters of unsaturated acids, e.g., of methyl 3-butenoate. (C) 2002 Elsevier Science B.V. All rights reserved.