The broad presence of azaarene moieties in natural products has promoted the development of new functionalization reactions, giving access to larger libraries of bioactive compounds. The light promoted [2 + 2] photocycloaddition reaction to generate cyclobutanes has been extensively studied in photochemistry. In particular, De Mayo reported the [2 + 2] cycloaddition followed by retroaldol condensation between enols of 1,3-dicarbonyls and double bonds to synthesize 1,5-dicarbonyls. Herein, we describe the [2 + 2] photocycloaddition followed by a ring-opening rearomatization reaction between electron-deficient 2-methylene-azaarenes and double bonds, taking advantage of the ability of these heterocyclic derivatives to form the corresponding pseudo-enamine intermediate. The procedure shows a high functional group tolerance either on the double bond or the heteroarene side and allows the presence of different electron-withdrawing groups. In addition, the wide applicability of this reaction has been demonstrated through the late-stage derivatization of several natural products. Photochemical studies, together with theoretical calculations, support a mechanism involving the photosensitization of the pseudo-enamine intermediate.

天然产物中氮杂芳烃部分的广泛存在促进了新功能化反应的发展，从而获得了更大的生物活性化合物库。光促进 [2 + 2] 光环加成反应生成环丁烷已在光化学中得到广泛研究。特别是，De Mayo 报道了 [2 + 2] 环加成，然后是 1,3-二羰基的烯醇和双键之间的逆醛醇缩合以合成 1,5-二羰基。在此，我们描述了 [2 + 2] 光环加成，然后是缺电子 2-亚甲基-氮杂芳烃和双键之间的开环重芳构化反应，利用这些杂环衍生物形成相应伪-烯胺中间体。该程序在双键或杂芳烃侧显示出高官能团耐受性，并允许存在不同的吸电子基团。此外，该反应的广泛适用性已通过几种天然产物的后期衍生化得到证明。光化学研究连同理论计算支持一种涉及假烯胺中间体光敏化的机制。