Alkylthio‐functionalized, o‐anilide‐embedded enynes, that is, N,S‐1,6‐enynes, were efficiently reacted with elemental sulfur to afford thiophene‐fused N‐heterocycles. The one‐pot sulfur incorporation/cascade cyclization strategy offers a straightforward route to 4H‐thieno[3,2‐b]indoles and thieno[3,4‐c]quinoline‐4(5H)‐thiones through the tunable Csp−Csp and Csp−Csp³ bond cleavages of the N,S‐1,6‐enynes, forming both a N‐heterocycle and a fused thiophene ring. The five‐ring π systems azacyclopenta[f,g]tetracene scaffolds were also obtained from the cascade cyclization of 2‐halogen‐functionalized thieno[3,4‐c]quinoline‐4(5H)‐thiones. The present synthetic protocol avoids use of prefunctionalized indole and thiophene derivatives as the building blocks for the construction of thiophene‐fused N‐heterocycles under metal‐free conditions.

中文翻译：

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N，S-炔烃向噻吩融合的N-杂环的无金属Csp-Csp和Csp-Csp3键断裂

烷硫基官能化的邻苯二甲酰亚胺嵌入的炔烃，即N，S -1,6-炔烃，可与元素硫有效反应，得到噻吩稠合的N杂环。一锅硫掺入/级联环化策略为通过可调C sp制备4 H-噻吩并[3,2- b ]吲哚和噻吩并[3,4- c ]喹啉-4（5 H）-硫酮提供了一条简单的路线-C sp和C sp -C sp ³键合N，S -1,6-烯炔的裂解，形成一个N杂环和稠合的噻吩环。五环π系统氮杂双环五[ f，g ]并四苯并架骨架也是从2卤素官能化的噻吩并[3,4- c ]喹啉-4（5 H）-硫酮的级联环化获得的。本合成方案避免了使用预官能化的吲哚和噻吩衍生物作为在无金属条件下构建噻吩稠合的N杂环的基础。