Allylic C–H acetoxylation of terminal alkenes over TiO₂ supported palladium nanoparticles using molecular oxygen as the oxidant

A method for synthesizing linear allylic acetates from terminal alkenes over TiO₂ supported Pd nanoparticles (NPs) has been developed, in which O₂ serves as the sole oxidant. Good catalytic activity was performed when using allylbenzene as a substrate and the catalyst can be reused at least five times without activity losing. The catalytic system has a broad substrate scope including transformation of 1,3-butadiene into 1,4-diacetoxy-2-butene, which is an important industrial intermediate for production of 1,4-butanediol. In contrast to previous reports that the Pd-catalyzed allylic acetoxylation is generally promoted by Pd^II species, the XAFS measurements suggest that this reaction is catalyzed over Pd⁰ NPs. Additionally, XPS analysis of the catalyst confirms the interaction between Pd and TiO₂, which probably promote the initial catalytic procedure.