Synthesis of 2‐Thioxohydropyridine‐3‐Carbonitrile, 2‐Alkylthiopyridine, Thienopyridine, Pyrazolopyridine Derivatives and Their Theoretical Calculations

Cyanothioacetamide (1) reacted with but‐2‐enal (2) to give the corresponding 4‐methyl‐2‐sulfanylpyridine‐3‐carbonitrile (7) which was used as a good starting material for the synthesis of 1‐(3‐amino‐4‐methylthieno[2,3‐b]pyridin‐2‐yl)ethan‐1‐one (10), 3‐amino‐4‐methylthieno[2,3‐b]pyridine‐2‐carboxamide (15), 3‐amino‐4‐methylthieno[2,3‐b]pyridine‐2‐carboxylate (18) and 3‐amino‐4‐methylthieno[2,3‐b]pyridin‐2‐ylarylketone 25a‐c through its reactions with each of (1‐chloroacetone (8), 3‐chloropentane‐2,4‐dione (11) or ethyl 2‐chloro‐3‐oxo‐butanoate (19)), 2‐chloroacetamide (13), ethyl 2‐chloroacetate (16) and 2‐bromo‐1‐arylethan‐1‐one 23a‐c, respectively. Considering the data of elemental analyses, IR, 1HNMR, mass spectra and theoretical calculations, structures of the newly synthesized heterocyclic compounds were elucidated.