Rh(iii)-catalyzed C–H activation/cycloaddition of benzamides and methylenecyclopropanes: divergence in ring formation

An unprecedented Rh(III)-catalyzed C–H activation/cycloaddition of benzamides and methylenecyclopropanes for the selective synthesis of spiro dihydroisoquinolinones and furan-fused azepinones is reported. The process features simple starting materials, mild conditions, and high efficiency and is external oxidant free. The products could be easily converted to other biologically interesting heterocycles. Control experiments and kinetic isotope effect studies were conducted and a plausible mechanism is proposed.