1,4-CARBOSILYLATION OF 1,3-DIENES VIA PALLADIUM-CATALYZED 3-COMPONENT COUPLING REACTION

Three-component coupling reaction of acid chlorides, organodisilanes, and 1,3-dienes achieves 1,4-carbosilylation of the 1,3-dienes to afford allylic silanes as the product. Bis(dibenzylideneacetone)palladium, a naked Pd(0) complex without donating ligand, showed high catalytic activity. A carbon and a silicon substituent are introduced at 1- and 4-positions of the 1,3-dienes regio- and stereoselectively with concomitant decarbonylation of the acid chlorides. A wide variety of allylic silanes are synthesized in high yields from these easily accessible substrates. On the other hand, a bully acid chloride such as adamantane-1-carboxylic acid chloride did not undergo the decarbonylation reaction but afforded allylic silanes containing acyl functionality. In all these reactions, transmetalation of the disilanes with eta(3)-allylchloropalladium intermediates might be a critical step in the catalytic cycle. As a model reaction for the transmetalation, reaction of di-mu-chlorobis[(1,2,3-eta)-4-phenyl-2-butenyl]dipalladium with disilanes was carried out. Although intermediate eta(3)-allylsilylpalladium species could not be detected, the corresponding allylic silanes, silyl chlorides, and Pd(0) metal were formed during the reaction. Furthermore, a similar three-component coupling reaction using aryl iodides, organosilylstannanes, and dienes also proceeded. However, the selectivity and the yield decreased considerably.