Regio- and stereoselective synthesis of (Z)-beta-silylalkenylboranes by silaboration of alkynes catalyzed by palladium and platinum complexes

Addition of the silicon-boron bonds of (dimethylphenylsilyl)boranes having pinacol, catechol, and diethylamino groups on the boron across carbon-carbo n triple bonds is effectively catalyzed by palladium complexes. The silabor ation of a variety of terminal alkynes took place with almost complete regi o- and stereoselectivity to afford (Z)-1-boryl-2-silylalkenes in high yield s. The silaboration products were subjected to the palladium-catalyzed cros s-coupling reaction with aryl iodide and rhodium-catalyzed conjugate additi on to methyl vinyl ketone, giving beta-silylstyrene derivatives and delta-s ilyl-gamma,delta-unsaturated ketones, respectively, in high yields. (C) 199 9 Elsevier Science Ltd. AII rights reserved.