Synthesis with Nitriles: Synthesis of Some New Mercapto-pyridazine Mercaptopyridazino16-aquinazoline and Thiophene Derivatives

摘要

2-(1-(4-Bromophenyl)-2-thiocyanatoethylidene)malononitrile (>3) undergoes azo coupling with diazotized aromatic amines to afford arylhydrazone derivatives, which are readily cyclized to afford the corresponding 3(2H)-pyridazinimine derivatives upon reflux in aqueous NaOH. Under similar condition an o-cyanoarylhydrazone derivative was cyclized into 6H-pyridazino[1,6-a]quinazolin-6-imine, which in turn was easily transformed into 6H-pyridazino[1,6-a]quinazolin-6-one on reflux in ethanolic/HCl. Compound >3 afforded substituted 5-acetylthiophene derivatives upon reflux in AcOH/HCl mixtures.