Visible-Light-Induced Catalysis: A Regioselectivity Switch between [2+1] and [2+2] Cycloaddition of Diazocarbonyls with Olefins

Abstract Visible-light-promoted [2+1] and [2+2] cycloaddition reactions of diazocarbonyls with olefins have been developed, affording functionalized cyclopropanes and cyclobutanes, respectively. In visible-light catalysis of Ir(ppy)3, a simple addition of Rh2(OAc)4 switches the regioselectivity from [2+1] to [2+2] cycloaddition with good reactivity and high regioselectivity.