Studies with pyridazines and condensed pyridazines: Routes for synthesis of 3‐amino‐5‐aryl‐2,5‐dihydro‐pyridazine, 10a<i>H</i>‐pyridazino[1,6‐<i>a</i>]quinazoline and thieno[3,4‐<i>d</i>]pyridazinone

Abstract

Abstract magnified image Novel routes to 3‐aminopyridazines, 10a H ‐pyridazino[1,6‐ a ]quinazoline and, thieno[3,4‐ d ]pyridazine utilizing the reaction of 2‐oxobutanal‐1‐arylhydrazones 3a,b with α,β‐unsaturated nitriles are described. Condensation of 3 with ethyl cyanoacetate afforded pyridazinones that reacted with sulphur yielding thienopyradazinone 10 . Reaction of 10 with maleic anhydride and acrylonitrile afforded products of addition and hydrogen sulphide elimination. On other hand reacting 10 with enaminone and ethyl propionate afforded the product of addition of the amino function to activated double bond.