Polyethylene glycol mediated catalyst-free synthesis of 5,9b-dihydro-1H-[1,2,4] triazino[5,6-b]indole-3-ols/thioles

An efficient one pot environmentally benign chemical synthesis of 5,9b-dihydro-1H-[1,2,4] triazino [5,6-b] indole-3- ols and 5,9b-dihydro-1H-[1,2,4] triazino [5,6-b] indole-3-thiols is carried out in PEG as a recycle reaction medium under neutral conditions by using isatin, and semicarbazide/thiosemicarbazide. No additional base or solvents are utilized.