“In Situ” Generated “HCl”: A Highly Efficient Catalyst for One-Pot Synthesis of 1H-Indazolo [1,2-b]phthalazine-1,6,11-triones and 1Hpyrazolo[1,2-b]phthalazine-5,10-diones under Solvent-Free Conditions

<p>The rapid and environmental synthetic route to produce 1<em>H</em>-indazolo[1,2-b] phthalazine-1,6,11-triones and 1<em>H</em>-pyrazolo[1,2-b]phthalazine-5,10-diones derivatives have been developed <em>via</em> multicomponent and one-pot reactions of various aldehydes, cyclic or acyclic 1,3-diketones with: <em>i)</em> phthalhydrazide or <em>ii)</em> phthalic anhydride-hydrazinium hydroxide using wet 2,4,6-trichlorotriazine (TCT) as catalyst under solvent-free conditions. Simple and mild reaction conditions, the use of a cheap catalyst and easy workup and isolation are notable features of this method.</p>