Synthesis of novel 5H, 11H‐pyrido[2′,3′:2,3]thiopyrano[4,3‐b]‐indoles by fischer‐indole cyclization

Abstract

The synthesis of the title compounds 5H, 11H‐pyrido[2′,3′:2,3]thiopyrano[4,3‐b]indoles was accomplished by the Fischer indole cyclization of some 2,3‐dihydrothiopyrano[2,3‐b]pyridin‐4(4H)‐one phenylhydrazones and 7‐methyl‐2,3‐dihydrothiopyrano[2,3‐b]pyridin‐4(4H)‐one phenylhydrazones. The synthesis of the new 2,3‐dihydrothiopyrano[2,3‐b]pyridin‐4(4H)‐one, which was used as one of the starting compounds, is also described.

Synthetic Approaches to 2‐Alkylthiochroman‐4‐ones and Thioflavanones

“…Compound 27 was treated with anhydrous sodium acetate in acetic anhydride for 1.5 h at 160 °C to afford 2,3‐dihydrothiopyrano [2,3‐ b ]pyridin‐4‐(4 H )‐one ( 28 ) (Scheme 15). 31 …”

Synthesis, Labeling and Biological Evolution of New Thiopyrano[2,3-b]Pyridine Derivatives as Potential Anticancer Agents

“…6,7 Some of 4-oxothiopyrano [2,3-b] pyridines were reported as potential antihypertensive agents. 8,9 α,β-Unsaturated compounds have also exhibited excellent antitumor, anti-inflammatory, antimalarial and other pharmacological effects. [10][11][12][13] In recent years, the synthesis and antifungal activities of 3-substituted methylene-4-oxothiopyrano [2,3-b]pyridines were published.…”

Synthesis of novel pyrido[3′,2′:5,6]thiopyrano[3,2‐b]indol‐5(6H)‐ones and 6H‐pyrido[3′,2′:5,6]thiopyrano[4,3‐b]quinolines, two new heterocyclic ring systems

“…They were prepared starting from the 2,3-dihydrot h i o p y r a n o [ 2 , 3 -b] p y r i d i n -4 ( 4H) -o n e s 2 a -b [12,13], by known reactions employed in the literature for the obtainment of analogous tetracyclic systems [14][15][16][17][18]. Compounds 2a-b revealed to be versatile intermediates as, recently, they were used for the synthesis of new pyridothiopyrano[4,3-b]indole system 1 [12], which is structurally related to the novel heterocycle A.…”

“…Compounds 2a-b revealed to be versatile intermediates as, recently, they were used for the synthesis of new pyridothiopyrano[4,3-b]indole system 1 [12], which is structurally related to the novel heterocycle A.…”

“…2 , 3 -D i h y d r o t h i o p y r a n o [ 2 , 3 -b] p y r i d i n -4 ( 4H)-one 2 a [12] and the corresponding 7-methyl derivative 2 b [ 1 3 ] represented the starting material for the preparation of the heterocyclic system B. Compounds 2 a -b and oaminobenzaldehyde were allowed to react in ethanol solution, at reflux in the presence of potassium hydroxide, to yield (>60%) the desired 6H-p y r i d o [ 3 ' , 2 ' : 5 , 6 ]t h i o p y r a n o [ 4 , 3 -b]quinolines 10a-b (Scheme 2).…”