N,2-Dibromo-6-chloro-3,4-dihydro-2H-benzo[e]-[1,2,4]thiadiazine-7-sulfonamide 1,1-dioxide: an efficient and homogeneous catalyst for one-pot synthesis of 4H-pyran, pyranopyrazole and pyrazolo[1,2-b]phthalazine derivatives under aqueous media

N,2-Dibromo-6-chloro-3,4-dihydro-2H-benzo[e][1,2,4]thiadiazine-7-sulfonamide 1,1-dioxide (DCDBTSD) as a highly efficient and homogeneous catalyst was successfully applied for the synthesis of 4H-pyran, pyranopyrazole and pyrazolo[1,2-b] phthalazine derivatives by a one-pot multi-component reaction (MCR) in water. The described method has some advantages such as mild and neutral reaction media, high yields, short reaction times, cleaner and easier reaction profiles and compliance with green chemistry protocols.