Lewis acid-catalyzed regioselective C–H carboxamidation of indolizines with dioxazolones via an acyl nitrene type rearrangement

An efficient, direct, and novel Lewis acid-catalyzed regioselective C–H carboxamidation of indolizines with dioxazolones via an acyl nitrene type rearrangement under metal-free conditions has been documented. A diverse array of indolizine-3-carboxamides were achieved in moderate to good yields with wide substrate scope. In these transformations, isocyanatobenzene was formed by the ring opening of dioxazolones and a subsequent Curtius-type rearrangement, which could be harnessed in C–H carboxamidation of N-heterocycles. The present protocol is satisfactorily complementary to nitrene transfer chemistry and C–H functionalization of N-heterocycles. Furthermore, photophysical experiments revealed that a few compounds exhibited high fluorescence absorption and emission intensity.