Microwave Irradiation for Accelerating each Step for the Synthesis of 1,2,4-Triazino[5,6-b]indole-3-thiolsand their Derivatives from Isatin and 5-Chloroisatin

Microwave irradiation has been used to accelerate the conversion of isatin (1), 5-chloroisatin (2), and N-benzylisatin (3) to their thiosemicarbazones and their subsequent cyclization into 1,2,4-triazino[5,6-b]indole-3-thiols 7 and 8; and the N-benzyl derivative 9. Selective and complete alkylation of 1, 7, 8, and 9 has also been achieved under microwave irradiation.