Pure and Applied Chemistry

Abstract: A new hydrosilylative cross-coupling reaction of a variety of alkynes with several alkenes, which is catalyzed by a cationic Pd complex [Pd(η³-C₃H₅)(cod)]⁺[PF₆]^- (cod = 1,5-cyclooctadiene) was studied systematically. The reaction using HSiCl₃ as an addend afforded more or less two types of products consisting of four possible derivatives, R¹CH=CR²-CHR³-CHR⁴-SiCl₃, which always contained 4-trichlorosilyl-1-butene frameworks, in acceptable combined yields. The coupling pattern was markedly dependent both on the precatalyst in the absence or presence of PPh₃ ligand and on the combination of the alkyne and alkene partners employed. A possible catalytic cycle that involves an initial hydropalladation of an alkyne, followed by a facile and specific carbopalladation of an alkene, is proposed. At the same time, the lack of regioselectivity in the latter step is noted.