Microwave-Assisted PEG-400 Medaited Synthesis of 4,5-dihydro-1H-benzo[g]indazole Derivatives: An Enaminone Approach

A simple, rapid and conceptually new efficient protocol for the synthesis of 4,5-dihydro-1H-benzo[g]indazole derivatives from novel enaminones prepared via Blaise reaction under catalyst free conditions is reported involving polyethylene glycol (PEG-400) as an efficient recyclable medium without using any organic co-solvent or additive by Microwave irridation with 91-95 % yields without chromatography.