Phototriggered Fluoroalkylation/Cyclization of Unactivated 1‑Acryloyl-2-cyanoindoles: Synthesis of RCOCF2‑Substituted Pyrrolo[1,2‑a]indolediones

A photochemical
approach toward RCOCF2-substituted pyrrolo­[1,2-a]­indolediones was developed by the radical cascade difluoroalkylation/cyclization
reaction of unactivated 1-acryloyl-2-cyanoindoles with ethyl iododifluoroacetate
or iododifluoramides under visible-light irradiation. This transition-metal-
and photosensitizer-free protocol afforded diverse difluoroalkylated
pyrrolo­[1,2-a]­indolediones in moderate to good yields
under mild reaction conditions. Most appealingly, the reaction can
proceed smoothly under sunlight irradiation, which opens a new avenue
toward difluoroalkylated pyrrolo­[1,2-a]­indolediones.

一种通过自由基级联的二氟烷基化/环化反应，以无活化1-丙烯酰-2-氰基吲哚与乙基碘二氟乙酸酯或碘二氟酰胺在可见光照射下反应，实现RCOCF2取代的吡咯[1,2-a]吲哚二酮的光化学合成方法得到开发。该无过渡金属和光敏剂参与的方案，在温和的反应条件下，以中等到良好的产率提供了多样化的二氟烷基化吡咯[1,2-a]吲哚二酮。尤为引人注目的是，该反应可在日光照射下顺利进行，为二氟烷基化吡咯[1,2-a]吲哚二酮的合成开辟了新的途径。