PhI(OAc)2-mediated novel 1,3-dipolar cycloaddition of methylenecyclopropanes (MCPs), vinylidenecyclopropanes (VCPs), and methylenecyclobutane (MCB) with phthalhydrazide

Iodobenzene diacetate-mediated reactions of methylenecyclopropanes 1, vinylidenecyclopropanes 2, and a methylenecyclobutane 3a with phthalhydrazide give the corresponding [3+2] cycloaddition products in good yields under mild conditions. In these reactions, phthalhydrazide was transformed to a 1,3-dipole intermediate in the presence of iodobenzene diacetate. A plausible reaction mechanism has been proposed.