Catalyst-Free [3 + 2] Cycloaddition of Benzimidazole Esters and Quinone Esters: Divergent Synthesis of N-Heterocycles

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Herein, we disclose a catalyst-free [3 + 2] cycloaddition of benzimidazole esters and quinone esters for the efficient and atom-economical construction of benzo[ d ]imidazol-2-ylidene-2,3-dihydrobenzofurans in good to excellent yield with excellent E -type selectivity. Interestingly, subsequent lactamization leads to divergent synthesis of valuable benzo[4,5]imidazo[1,2- b ]furo[4,3,2- de ]isoquinoline derivatives with high efficiency without column chromatography isolation under base conditions. In addition, this cycloaddition also features theoretical calculations, mild conditions, broad substrate scope, and great potential for optical activity.