Studies on v-triazoles. 7. Antiallergic 9-oxo-1H,9H-benzopyrano[2,3-d]-v-triazoles

A series of the little compounds was prepared by cyclization of the appropriate 5-(aryloxy)-v-triazole-4-carboxylic acids and evaluated for antiallergic activity by the rat passive cutaneous anaphylaxis (PCA) screen. The most potent compounds were 6-(mesyloxy)-9-oxo-1H,9H-benzopyrano[2,3-d]-v-triazole and its 5-methyl homologue, which were some tenfold more potent than disodium cromoglycate. Dialkyl derivatives, especially those substituted at C-5 and C-6 or C-6 and C-7, and 6-methoxy compounds were also among the more potent compounds. One compound, 6,7-dimethyl-9-oxo-1H,9H-benzopyrano[2,3-d]-v-triazole, was further evaluated and shown to be a potent inhibitor of rat PCA when given orally.