Download PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... The hydrohydrazination of 4-pentynoic acid with different arylhydrazines proceeds smoothly in the presence of zinc chloride. The domino amination–amidation sequence leads to aryl-substituted 4,5-dihydro-3( 2H)-pyridazinones. ... The hydrohydrazination of 4-pentynoic acid in the presence of zinc ...