Synthesis of 4,10-dihydro-4,10-dioxo-1H[1]benzothiopyrano[3,2-b]pyridine and 7-oxo-7,13-dihydro[1]benzothiopyrano[2,3-b]-1,5-benzodiazepine

Article abstract of DOI:10.1002/jhet.5570220123

3-Amino-4H-1-benzothiopyran-4-one (3-aminothiochromone) was easily prepared by reaction of 3-bromothiochromen-4-one with sodium azide in methanol-water. Condensation of 3-aminothiochromone with diethyl ethoxymethylenemalonate and with dimethyl acetylenedicarboxylate gave intermediates, which were thermally cyclized to give 4,10-dihydro-4,10-doxo-1H[1]benzothiopyrano[3,2-b]pyridinecarboxylates. 3-Formyl-thiochromone was condensed with o-phenylenediamine to give 7-oxo-7,13-dihydro[1]benzothiopyrano[2,3-b]-1,5-benzodiazepine.