Parallel solution-phase synthesis of 4H-benzo[1,4]thiazin-3-one and 1,1-dioxo-1,4-dihydro-2H-1lambda6-benzo[1,4]thiazin-3-one derivatives from 1,5-difluoro-2,4-dinitrobenzene.

This paper discusses the synthesis of privileged structures 4H-benzo[1,4]thiazin-3-one and 1,1-dioxo-1,4-dihydro-2H-1lambda6-benzo[1,4]thiazin-3-one derivatives in a parallel solution-phase manner using 1,5-difluoro-2,4-dinitrobenzene. Each scaffold possesses four diversity points. A cheap and efficient oxidant, urea-hydrogen peroxide (UHP), was applied for the introduction of the sulfone group. The intramolecular cyclization to 1,1-dioxo-1,4-dihydro-2H-1lambda6-benzo[1,4]thiazin-3-one was achieved by microwave assistance or the use of an inorganic base.