Expanding the scope of trialkylborane/water-mediated radical reactions.

The dehalogenation of alkyl iodides, as well as the chemoselective deoxygenation of a secondary alcohol in the presence of various alkyl and aryl halides, can be accomplished employing a trialkylborane/air/water system.

Deoxygenation of alcohols employing water as the hydrogen atom source.

Trialkylboranes (BMe3, BEt3, and BBu3) have been shown to mediate reductive deoxygenation reactions of O-alkyl-S-methyl dithiocarbonates (methyl xanthates) in which water or deuterium oxide functions as the source of hydrogen or deuterium. This method has proven versatile with regard to substrate scope and is capable of providing protio- or deuterioalkane products in high yields with excellent levels of D-incorporation. Ab initio calculations suggest that the trialkylborane-water complex possesses an unusually low O-H bond dissociation energy (73 kcal/mol) and support a radical chain mechanism for this process. Taken together, this report provides evidence for fundamentally novel and previously overlooked modes of reactivity for water and trialkylboranes of wide ranging importance in both theoretical and applied investigations.