Synthesis and screening of 1, 3, 4-oxadiazinoindolinone and <i>s</i>-triazole derivatives of pyranobenzopyran

Abstract

3-Formyl-4- hydroxycoumarin is treated with malonic acid in the presence of zinc chloride catalyst to give 2<i>H</i>, 5<i>H</i>-2,5-dioxo-3-pyrano[3, 2-<i>c</i>]benzopyranoic acids <b>1a-d </b>which on treatment with methanol in the presence of thionyl chloride give methyl 2<i>H</i>, 5<i>H</i>-2,5-dioxopyrano[3, 2-<i>c</i>]benzopyran-3-oates <b>2a-d</b>. Compounds <b>2a-d </b>were converted into their acid hydrazides <b>3a-d</b>.<b> 3a-d </b>on treatment with isatin yield 1<i>H</i>, 2<i>H</i>-3-(2<i>H</i>, 5<i>H</i>-2,5-dioxopyrano[3, 2-<i>c</i>]benzopyran-3-carboxyhydrazono)-2-indolinones <b>4a-d</b> which on cyclisation with conc. H₂SO₄ afford 3-[1, 3, 4-oxadiazino[5, 6-<i>b</i>]indol-2-yl]-2,5-dioxopyrano[3,2-c]benzopyrans <b>5a-d</b>. Acid hydrazides <b>3a-d</b> on treatment with carbon disulfide in 10% KOH at room temperature followed by treatment with ortho-chlorobenzoic acid hydrazide furnish 3-(2<i>H</i>, 5<i>H</i>-2, 5-dioxopyrano[3, 2-<i>c</i>]benzopyran-3-yl)-4-{N-2'-chlorophenylcarboxamido]-5-mercapto-1,2,4-triazoles <b>6a-d</b>.