The catalytic dearomatization of pyridines, accessing medicinally relevant N-heterocycles, is of high interest. Currently direct, dearomative strategies rely generally on reduction or nucleophilic addition, thus limiting the architecture of the dearomatized products to a six-membered ring. We herein introduce a catalytic, dearomative cycloaddition reaction with pyridines using photoinduced energy transfer catalysis, thereby advancing dearomatization methodology and increasing the topology of pyridine dearomatization products. This unprecedented method features high yields, broad substrate scope (44 examples), excellent functional group tolerance, and facile scalability. Furthermore, a recyclable and sustainable polymer immobilized photocatalyst was employed. Computational and experimental investigations support a mechanism in which a cinnamyl moiety is promoted to its corresponding excited triplet state through visible-light-mediated energy transfer catalysis, followed by a regioselective and dearomative [4+2] cycloaddition to pyridines. This work demonstrates the contribution of visible light catalysis toward enabling thermally challenging organic transformations.

吡啶的催化脱芳香化作用，获得医学上相关的氮-杂环，引起了人们的极大兴趣。当前直接的脱芳香化策略通常依赖于还原或亲核加成，从而将脱芳香化产物的结构限制为六元环。我们在本文中介绍了使用光诱导的能量转移催化作用与吡啶进行的催化脱芳香环加成反应，从而推进脱芳香化方法，并增加了吡啶脱芳香化产物的拓扑结构。这种空前的方法具有高收率，广泛的底物范围（44个例子），出色的官能团耐受性和简便的可扩展性。此外，采用了可回收且可持续的聚合物固定化光催化剂。计算和实验研究支持一种机制，其中肉桂基部分通过可见光介导的能量转移催化被提升为其相应的激发三线态，然后向吡啶进行区域选择性和脱芳香性的[4 + 2]环加成。这项工作证明了可见光催化对实现热挑战性有机转化的贡献。