Copper (I)-Catalyzed Alkylation of Aryl- and Alkenylsilanes Activated by Intramolecular Coordination of an Alkoxide

摘要

Organosilicon-based cross-coupling has attracted much attention as a useful tool for carbon-carbon bond formation because of the low toxicity, high availability, and high chemical stability of organosilicon compounds. Activation of the unreactive Si-C bond, however, has been imperative and hence heteroatom-functionalized organosilanes such as halo- and alkoxysilanes have practically been employed in conjunction with a fluoride-ion activator for palladium-catalyzed cross-couplings. In recent advances, organosila-nols and silanolates, as well as silacyclobutanes have been introduced as silane coupling partners in the Hiyama coupling. The intramolecular coordination of heteroatoms to the silicon atom also activates the Si-C bond in the silicon-based coupling reactions. In this regard, the transition-metal-catalyzed cross-couplings of aryl- and alkenyldi-methyl[(2-hydroxymethyl)phenyl]silanes were extensively studied. In the Hiyama coupling, C(sp~2)-X electrophiles such as aryl and alkenyl (pseudo)halides have been successfully employed, but little is known about the coupling with unreactive C(sp~3)-X electrophiles. In this context, we aimed at the development of a catalytic cross-coupling of alkenyl- (1) and arylsilanes (2) with C(sp~3)-X electrophiles [Scheme 1, Eq. (1)].