Site-specific preparation of 4-substituted-6-fluoro(carboalkoxyl)benzo[b]furans and benzo[b]thiophenes via base-catalyzed cyclization of enyne derivatives

A site-specific synthesis of 4-substituted-6-fluoro(carboalkoxyl)benzo[b]furans and benzo[b]thiophenes is described. The reactions of heterocyclic aromatic aldehydes with a Wittig reagent, followed by Sonogashira reaction with terminal alkynes, and subsequent base-catalyzed cyclization site-specifically provide 4-substituted-6-fluoro(carboalkoxyl)benzo[b]furans and benzo[b]thiophenes in good yields.

Graphical abstractWe have demonstrated that 4-substituted-6-fluoro(carboalkoxyl)benzo[b]furans and benzo[b]thiophenes can be prepared site-specifically via base-catalyzed cyclization from the corresponding substituted enynes. Our work continues to explore new applications of this base-catalyzed cyclization in organic chemistry.Figure optionsDownload full-size imageDownload as PowerPoint slide