Synthesis and the Skraup reaction of amino-5H-benzothiopyrano[2,3-b]pyridin-5-ones

The new amino derivatives of 5 H-[1]benzothiopyrano[2,3-b]pyridin-5-one were synthesized. The Skraup reaction of these amino-5 H-[1]benzothiopyrano [2, 3-b]pyridin-5-ones was conducted in the presence of glycerol, fuming sulfuric acid, nitrobenzene, iron (II) sulfate and boric acid. 6-Amino-, 7-amino-, 8-amino- and 9-Amino-5 H-[1]benzothiopyrano [2,3-b] pyridin-5-ones gave 12 H-pyrido[3', 2':5,6]thiopyrano [2,3-h]quinolin-12-one, 12 H-pyrido [3',2':5,6]thiopyrano [3,2-f]quinolin-12-one, 7 H-pyrido [3',2':5,6]thiopyrano[2, 3-f]quinolin-7-one and 7 H-pyrido [3',2':5,6]thiopyrano[3,2-h]quinolin-7-one, respectively.