Regioselective Multiboration and Hydroboration of Alkenes and Alkynes Enabled by a Platinum Single-Atom Catalyst

Abstract

Selective multiboration including di- and triboration and hydroboration of alkynes and alkenes face significant challenges in organic synthesis, including achieving high regioselectivity, functional group tolerance, and catalyst stability while requiring mild conditions to maintain reactivity. These transformations have been predominantly explored by using homogeneous catalysts. In this study, we report the scalable synthesis of heterogeneous platinum single-atom catalyst (Pt-SAC) supported on ultrathin nanosheets of graphitic carbon nitride via a rapid microwave-assisted method. The Pt-SAC enables 1,2-diboration of sterically hindered alkenes and 1,2,2-triboration of alkynes with B₂pin₂ under mild conditions. For the diboration of styrene, the catalyst achieves 99% yield with 95% selectivity, a turnover number (TON) of 3711, and a turnover frequency (TOF) of 247 h^–1. The catalyst also promotes the regioselective hydroboration of alkenes and alkynes, yielding anti-Markovnikov alkylboranes and vinylboranes, respectively. Computational calculations reveal that the enhanced reactivity on the Pt-SAC catalyst arises from adsorption-induced weakening of key bonds (C=C and B–H), thereby significantly lowering the activation energy barriers. The Pt-SAC exhibits stability and recyclability, maintaining performance over at least eight consecutive runs without detectable Pt leaching. This study highlights the potential of Pt-SAC as a robust and versatile platform for organoboron transformations under mild conditions, with relevance to applications in pharmaceutical, agrochemical, and polymer synthesis.