Synthesis and properties of hydrogenated 2-alkylthio-5-oxo-3-cyanoindeno [1,2-b]-pyridines
Condensation of 2-arylidene-1, 3-indandiones with cyanothioacetamide in the presence of piperidine, followed by treatment with alkyl halides, has given partially hydrogenated 2-alkylthio-5-oxoindeno [1,2-b]-pyridines, the oxidation, interconversion, and Thorpe cyclization of which to give a novel heterocyclic system, indeno [1′,2′:6,5] pyrido [2,3-b] thiophene, have been examined.