Mn(II)-catalyzed synthesis of benzo[f]indole-4,9-diones via vinyl azides and 2-hydroxynaphthoquinone

A novel, convenient and economical protocol to prepare polyfunctionalized benzo[f]indole-4,9-diones catalyzed by Mn(II) acetate from vinyl azides and 2-hydroxynaphthoquinone has been achieved. This reaction proceeded in good to excellent yields for a wide range of vinyl azides, and a possible mechanism has also been proposed.