Acetic Anhydride → 3-(4-Methoxyphenyl)-6H-[2]benzopyrano[4,3-c]pyridazin-6-one

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Reaction Steps

Acetic acid anhydride (100 ml), 2-[4-hydroxy-6-(4-methoxyphenyl)-3-pyridaziny]benzoic acid (11 g, 0.0342 mol) and toluene (100 ml) are reacted in a 250 ml flask; oil bath about 130° C. When the reaction is completed, the mixture toluene/acetic acid is distilled off at 96-108° C. (about 100 ml/1.5 hours). The acetic acid anhydride is eliminated under vacuum, the residue is taken up with methylene chloride (250 ml), washed with 5% aqueous sodium bicarbonate and then with water up to neutrality. THe organic layer is oven dried, and concentrated to dryness to give 3-(4-methoxyphenyl)-6H-[2]-benzopyrano[4,3-c]pyridazin-6-one 230°-231° C. (9,8 g; Yield 92%).

Provenance & Evidence