Assembly of Benzo[ c ][1,2]dithiol-3-ones via Acid-Promoted Denitrogenative Transannulation of Benzotriazinones.

An expedient synthesis of benzo[][1,2]dithiol-3-ones via metal-free denitrogenative transannulation of benzotriazinones is developed, which represents the first example of acid-mediated heteroannulation of benzotriazinones. This newly discovered reactivity of benzotriazinones enables the streamline synthesis of diverse benzo[][1,2]dithiol-3-ones in decent yields by using sodium sulfide as the sulfur source under simple reaction conditions.