The reaction of ethyl benzoylacetate with malononitrile: a novel synthesis of some pyridazine, pyridazino[2,3-a]quinazoline and pyrrole derivatives

Ethyl benzoylacetate undergoes Claisen condensation reaction with malononitrile to afford 2-cyano-5-phenyl-3,5-dioxopentanonitrile which could be cyclized into 2-aminopyran and coupled with diazonium salts to afford azo derivatives. These azo derivatives and those of ethyl benzoylacetate could be cyclized into 4-oxo-, 6-oxo- and 6-iminopyridazines and pyridazino[2,3-a]quinazolines, respectively. The 6-iminopyridazines could be transformed into the 6-oxopyridazines. The imino- and oxopyridazines could be transformed into pyrrole derivatives.