Cyclopropanation Using Electrons Derived from Hydrogen: Reaction of Alkenes and Hydrogen without Hydrogenation

Have you ever imagined reactions of alkenes with hydrogen that result in anything other than hydrogenation or hydrogenative C–C coupling? We have long sought to develop not only hydrogenation catalysts that activate H2 as hydride ions but also electron transfer catalysts that activate H2 as a direct electron donor. Here, we report the reductive cyclopropanation of alkenes using an iridium electron storage catalyst with H2 as the electron source without releasing metal waste from the reductant. We discuss the catalytic mechanism with selectivity to give the trans-isomer. These findings are based on the isolation of three complexes and density functional theory calculations.