A Pd-Au alloy efficiently catalyzed the [2+2+2] cycloaddition of substituted alkynes. Whereas monometallic Pd and Au catalysts were totally ineffective, Pd-Au alloy nanoparticle catalysts with a low Pd/Au molar ratio showed high activity to give the corresponding polysubstituted arenes in high yields. A variety of substituted alkynes participated in various modes of cycloaddition under Pd-Au alloy catalysis. The Pd-Au alloy catalysts exhibited high air tolerance and reusability.

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.

AP d-Aua lloy efficiently catalyzedt he [2+ +2+ +2] cycloaddition of substituted alkynes.W hereas monometallic Pd and Au catalysts were totally ineffective,P d-Au alloy nanoparticle catalysts with al ow Pd/Au molar ratio showed high activity to give the corresponding polysubstituted arenes in high yields.Avariety of substituted alkynes participated in various modes of cycloaddition under Pd-Au alloyc atalysis. The Pd-Au alloyc atalysts exhibited high air tolerance and reusability.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

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