A green and efficient process for the synthesis of Benzothiazinones using Phosphate fertilizers MAP, DAP and TSP as heterogeneous catalysts

The aim of this work is to prove the efficiency of the Phosphate fertilizers mono-ammonium phosphate (MAP), di-ammonium phosphate (DAP) and triple-super phosphate (TSP) as a “green” heterogeneous catalysts for the synthesis of 2-aryl-2H-benzo[b][1,4]thiazin-3(4H)-ones via the C-S and C-N coupling process of gem-dicyano epoxide with α-aminothiophenol. To optimize the reaction conditions, the synthesis was conducted with a range of solvents, catalyst amounts and catalyst particle sizes. Also, the potential recyclability of the catalysts was confirmed by running the reaction using the recycled catalyst.