Direct synthesis of C3-alkynyl pyrroloindolines from tryptamines via a visible-light-induced radical cascade reaction.

A visible-light-induced radical cascade reaction for the direct alkynylation of tryptamines with alkynyl sulfones was developed, affording a series of C3-alkynyl pyrroloindolines in excellent yields. This method features readily available substrates, good functional group tolerability, and scalability. C3-alkynyl pyrroloindolines show great potential as useful building blocks in the preparation of complex and valuable pyrroloindoline alkaloids.