Photo‐induced molecular transformations. Part 123. One‐step synthesis of 1<i>H</i>‐benz[<i>f</i>]indole‐4,9‐diones by a new regioselective photoaddition of 2‐amino‐1,4‐naphthoquinone with various alkenes and its application to one‐step synthesis of kinamycin skeleton

Abstract

Abstract 2,3‐Dihydro‐1 H ‐benz[ f ]indole‐4,9‐diones are formed in one‐step in 45–82% yields by an unprecedented [2+3]‐type regioselective photoaddition of 2‐amino‐1,4‐naphthoquinone with various electron‐rich alkenes and the [2+3] adducts derived from ammonaphthoquinone with vinyl ethers and vinyl acetate to give 1 H ‐benz[ f ]indole‐4,9‐diones including a benzindole‐dione with a kinamycin skeleton in 33–72% yields. A probable pathway leading to the formation of the dihydroindole‐dione involving air oxidation of an intermediary hydroquinone is proposed.