A New Preparation of Substituted 4H-1-Benzothiopyran-4-ones from C(α),N-Benzoylhydrazones or C(α),N-Carboalkoxyhydrazones and Methyl Thiosalicylate

Article abstract of DOI:10.1002/jhet.5570350109

C(α),N-Benzoylhydrazones or C(α),N-carboalkoxyhydrazones were dilithiated with excess lithium diisopropylamide, and the dianion-type intermediates were condensed with lithiated methyl thiosalicylate, followed by cyclization/hydrolysis to substituted 4H-1-benzothiopyran-4-ones (thioflavones/thiochromones).