Synthesis of Terminal Vinylindoles via Rh III -Catalyzed Direct C-H Alkenylation with Potassium Vinyltrifluoroborate.

An efficient Rh-III-catalyzed direct C2-alkenylation of indoles using readily available potassium vinyltrifluoroborate under mild conditions has been developed. This protocol features wide substrate scope and excellent functional group compatibility, enabling a facile access to diverse terminal vinylindoles in moderate to good yields. Furthermore, the C2-alkenylated indole can be easily transformed into 9H-carbazole through a ring-closing metathesis/aromatization cascade.