Synthesis of Terminal Alkenylindolines via Rhodium-Catalyzed Direct CH Alkenylation With Alkenyl Borates

Abstract

An efficient method for the synthesis of valuable terminal C7-alkenylated indolines through the direct C–H alkenylation of N-pyridinyl indolines in the presence of a rhodium catalyst has been developed. Alkenyl borates were first used as a useful alkenyl reagent for C–H functionalization of indolines. Under mild reaction conditions, a series of indolines with different functional groups were compatible in this transformation, affording the C7-alkenylated product in good to excellent yields. Moreover, the C7-alkenylated indoline can be conveniently converted to the pyrroloquinoline derivative, which is a popular tricyclic indoline skeleton in bioactive compounds, highlighting its potential application value.