One-Pot Syntheses of 1H-Pyrazolo[1,2-B]Phthalazine-5,10-Diones and 2-H-Indazolo[2,1-B]Phthalazine-1,6,11(13-H)-Triones in Water by Auto Catalysis

One-pot, four component syntheses for the preparation of 1-H Pyrazolo[1,2-b]phthalazine- 5,10-diones (5a-5h) and 2H-indazolo[2,1-b]phthalazine-1,6,11(13-H)-triones (7a-7f) have been described from phthaloyl dichloride (1) , hydrazine hydrate (2), benzaldehydes (3) and malononitrile (4a), ethyl cynoacetate (4b) or dimedone (6) in refluxing water for 1-1.5 h by in-situ generation of HCl as a catalyst. These reactions have easy workup, provide excellent yields, and use water as the solvent.