Synthesis of Benzo[ e ][1,3]-thiazine-2,4-diones via PPh 3 -Promoted [4 + 2] Annulation between Benzo[ c ][1,2]dithiol-3-ones and Carbamates

An efficient construction of benzo[ e ][1,3]-thiazine-2,4-diones through PPh 3 -promoted [4 + 2] annulation between benzo[ c ][1,2]dithiol-3-ones and carbamates is described herein. This novel strategy is distinguished by mild reaction conditions, convenient operation, excellent yields, wide functional group compatibility, accessible scalability, and practical transformations.