Synthesis, reactions and antimicrobial activity of new cyclopenta[e]thieno[2,3-b]pyridines and related heterocyclic systems

Reaction of the arylidene cyanothioacetamides 1a, b with cyclopentanone was proved to give a mixture of 4-aryl-3-cyanocyclopenta[b]pyridine-2(1H)-thio nes 2a, b and the corresponding 7-arylidene derivatives 3a, b. Compounds 2a , b were reacted with ethyl chloroacetate or chloroacetamide to give the pr omising S-substituted thiopyridines 6a-d. On treatment of the latter compou nds with sodium ethoxide in boiling ethanol, they underwent intramolecular Thorpe-Ziegler cyclization to yield the corresponding 3-amino-4-aryl-2-func tionalized-cyclopenta[e]thieno[2,3 -b]pyridines (7a-d). Most of these thien opyridines were reacted with a variety of reagents to produce other new cyc lopentathienopyridines as well as numerous of their condensed heterocyclic derivatives. Some of the compounds synthesized were tested in vitro for the ir antibacterial and antifungal activity.