Synthesis of 5, 9b-dihydro-1H-[1,2,4]triazino[5,6-b]indol-3-ol/thiol's using Sulfamic Acid, A Green and Recyclable Catalyst

A simple and highly efficient method has been developed for the synthesis of 5, 9b-dihydro-1H- [1, 2, 4]triazino [5, 6-b]indol-3-ols and 5, 9b-dihydro-1H- [1, 2, 4]triazino [5, 6-b]indole-3-thiols using sulfamic acid (H2NSO3H) as a green catalyst in water. The catalyst can be recovered by simple filtration and can be recycled in subsequent reactions. The method is simple, cost-effective and environmentally benign. By employing this method, a series of 14 compounds were synthesized.