Visible-light-promoted synthesis of alkylated Indolo[2,1-α]isoquinolines using 2‑Mercaptothiazolinium salts as alkyl radical source

A visible-light-induced radical cascade cyclization of 2-aryl-N-acryloyl indoles with 2‑mercaptothiazolinium salts is reported, furnishing the corresponding indolo[2,1-α]isoquinoline derivatives in good to moderate yields. A series of primary, secondary, and tertiary alkyl bromides were converted conveniently into redox-active thiazolinium salts, which are subsequently transformed into alkyl radicals through interaction with an excited-state photocatalyst. This green and environmentally protocol features broad substrate scope under mild conditions.