Synthesis and antiallergy activity of 4-oxopyrano[3,2-b]indoles

Abstract
A series of 4-oxopyrano[3,2-b]indole carboxylic acids, tetrazoles and carboxamidotetrazoles was prepared and tested for antiallergy potential in the rat passive cutaneous anaphylaxis (PCA) assay. Many of the compounds showed activity comparable or superior to that of cromolyn sodium or doxantrazole. Several compounds were orally active.