Efficient borylation of sp3 C–O bonds by supported Au catalysts is described. Au nanoparticles supported on TiO2 showed high activity under mild conditions employing low catalyst loading conditions without the aid of any additives, such as phosphine and bases. A variety of allyl, propargyl, and benzyl substrates participated in the heterogeneously catalyzed reactions to furnish the corresponding allyl, allenyl, and benzyl boronates in high yields. Besides, Au/TiO2 was also effective for the direct borylation of allylic and benzylic alcohols. A mechanistic investigation based on a Hammett study and control experiments revealed that sp3 C–O bond borylation over supported Au catalysts proceeded through SN1′-type mechanism involving the formation of a carbocationic intermediate. The high activity, reusability, and environmental compatibility of the supported Au catalysts as well as the scalability of the reaction system enable the practical synthesis of valuable organoboron compounds.

Supported palladium‐gold alloy‐catalyzed cross‐coupling of aryl chlorides and hydrosilanes enabled the selective formation of aryl‐silicon bonds. Whereas a monometallic palladium catalyst predominantly promoted the hydrodechlorination of aryl chlorides and gold nanoparticles showed no catalytic activity, gold‐rich palladium‐gold alloy nanoparticles efficiently catalyzed the title reaction to give arylsilanes with high selectivity. A wide array of aryl chlorides and hydrosilanes participated in the heterogeneously‐catalyzed reaction to furnish the corresponding arylsilanes in 34–80% yields. A detailed mechanistic investigation revealed that palladium and gold atoms on the surface of alloy nanoparticles independently functioned as active sites for the formation of aryl nucleophiles and silyl electrophiles, respectively, which indicates that palladium and gold atoms on alloy nanoparticles work together to enable the selective formation of aryl‐silicon bonds.magnified image

Since C­(sp3)–O bonds are a ubiquitous chemical motif in both natural and artificial organic molecules, the universal transformation of C­(sp3)–O bonds will be a key technology for achieving carbon neutrality. We report herein that gold nanoparticles supported on amphoteric metal oxides, namely, ZrO2, efficiently generated alkyl radicals via homolysis of unactivated C­(sp3)–O bonds, which consequently promoted C­(sp3)–Si bond formation to give diverse organosilicon compounds. A wide array of esters and ethers, which are either commercially available or easily synthesized from alcohols participated in the heterogeneous gold-catalyzed silylation by disilanes to give diverse alkyl-, allyl-, benzyl-, and allenyl silanes in high yields. In addition, this novel reaction technology for C­(sp3)–O bond transformation could be applied to the upcycling of polyesters, i.e., the degradation of polyesters and the synthesis of organosilanes were realized concurrently by the unique catalysis of supported gold nanoparticles. Mechanistic studies corroborated the notion that the generation of alkyl radicals is involved in C­(sp3)–Si coupling and the cooperation of gold and an acid–base pair on ZrO2 is responsible for the homolysis of stable C­(sp3)–O bonds. The high reusability and air tolerance of the heterogeneous gold catalysts as well as a simple, scalable, and green reaction system enabled the practical synthesis of diverse organosilicon compounds.

Efficient deoxygenative silylation of C(sp3)–O bonds with hydrosilanes by supported Au catalysts is described. Gold nanoparticles supported on TiO2 enabled various hydrosilanes to be used as sources of silyl groups in C–Si cross-coupling reactions. A variety of alkyl acetates and propargyl carbonates participated in the Au-catalyzed reactions to furnish the corresponding alkyl and allenylsilanes in high yields. In addition, Au/TiO2 was also effective for ring-opening silylation of cyclic ethers. A detailed mechanistic investigation corroborated that the title reaction involves the formation of silyl and alkyl radical intermediates, and the cooperation of Au nanoparticles as single-electron transfer catalysts and Lewis acid sites at the surface of metal oxides was responsible for the unusual reactivity of hydrosilanes for specific C(sp3)–Si bond formation.

Since C(sp3)–O bonds are a ubiquitous chemical motif in both natural and artificial organic molecules, the universal transformation of C(sp3)–O bonds will be a key technology for achieving carbon neutrality. We report herein that gold nanoparticles supported on amphoteric metal oxides efficiently generated alkyl radicals via homolysis of unactivated C(sp3)–O bonds, which consequently promoted C(sp3)–Si bond formation to give diverse organosilicon compounds. A wide array of esters and ethers which are either commercially available or easily synthesized from alcohols participated in the heterogeneous gold-catalyzed silylation by disilanes to give diverse alkyl-, allyl-, benzyl- and allenylsilanes in high yields. In addition, this novel reaction technology for C(sp3)–O bond transformation could be applied to the upcycling of polyesters, i.e., the degradation of polyester and the synthesis of organosilanes were realized concurrently by the unique catalysis of supported gold nanoparticles. Mechanistic studies corroborated the notion that the generation of alkyl radicals is involved in C(sp3)–Si coupling and the cooperation of gold and an acid-base pair on amphoteric oxides is responsible for the homolysis of stable C(sp3)–O bonds. The high reusability and air-tolerance of the heterogeneous gold catalysts as well as a simple, scalable, and green reaction system not only enabled the practical synthesis of diverse organosilicon compounds, but also contributed to the progress toward carbon neutrality.