We report a catalytic method for the direct deoxygenation of various C–O bond-containing functional groups. Using a Ni­(II) pre-catalyst and silane reducing agent, alcohols, epoxides, and ethers are reduced to the corresponding alkane. Unsaturated species including aldehydes and ketones are also deoxygenated via initial formation of an intermediate silylated alcohol. The reaction is chemoselective for C­(sp3)–O bonds, leaving amines, anilines, aryl ethers, alkenes, and nitrogen-containing heterocycles untouched. Applications toward catalytic deuteration, benzyl ether deprotection, and the valorization of biomass-derived feedstocks demonstrate some of the practical aspects of this methodology.

We report a one-step procedure to directly reduce unactivated aryl esters into their corresponding tolyl-derivatives. This is achieved by the action of a Ni/NHC catalyst and an organosilane reducing agent that is activated in situ by stoichiometric KOtBu. The resulting conditions provide a direct and efficient alternative to multi-step procedures for this transformation that often require use of hazardous metal hydrides. Applications in the synthesis of-CD3 containing products, derivatization of bioactive molecules, and chemoselective reduction in the presence of other CO bonds is demonstrated. File list (2) download file view on ChemRxiv Manuscript.pdf (1.92 MiB) download file view on ChemRxiv Supporting information.pdf (4.97 MiB)

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A reductive detrifluoromethylation protocol has been developed making use of an earth-abundant alkoxide base and silicon hydride species. A variety of pyridine and quinoline substrates bearing alkyl, aryl, and amino functional groups are reduced in moderate to high yields. The reaction is chemoselective for C(sp 2 )−CF 3 groups located at the 2-position on the pyridine ring, leaving trifluoromethyl groups located elsewhere on the molecule intact. Preliminary mechanistic studies demonstrate that the combination of silane and base generates a strongly reducing system that may transfer an electron to electron-deficient π systems.

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A Ni-catalyzed C–O bond activation is used to access alkenes directly from β-hydroxysulfones.

The coupling of tertiary alcohols with boronic esters is described, providing a direct access to quaternary carbon scaffolds without needing to proceed by a highly activated intermediate such as an alkyl halide. A dual catalyst system is employed with both Ni(0) and Bi(III) components playing a critical role along with a mild chlorosilane reactant that enhances the yield by alcohol silylation. This method was found to tolerate diverse functional groups including chloro, nitro, olefin, ketone, ester and phenol moieties, while also being applicable to the derivatization of heterocyclic scaffolds. Mechanistic studies suggest the combination of Lewis acid catalyst and organosilane promote heterolytic cleavage of the substrate C–O bond by an SN1-like reaction pathway, providing a powerful strategy for derivatizing readily available alcohols.