Synthesis and antitumor activity of some fused heterocyclic compounds based on cyclohepta[b]thiophene derivatives

Abstract

The reaction of 5,6,7,8-tetrahydro-4H-cyclohepta[b]thiophene derivatives 3a, b with acetic anhydride in presence of glacial acetic acid produced the acetamido derivatives 4a, b. Cyclization of the latter compounds gave the annulated products 5a, b. Compounds 3a, b reacted with one of the activated methylene groups of malononitrile (2a) and afforded compounds 7a, b through internal cyclization of the intermediates of compounds 6a, b. The latter products were reacted with the cyclic ketones 8a, b, c in presence of elemental sulphur and afforded compounds 9a-f. Compounds 3a, b reacted with different types of aldehydes 10a, b, c to produce compounds 11a-f. Finally the products11a-f reacted with hydrazine hydrate (12) affording compounds 14a-f via the proposed intermediate formation of compounds 13a-f. The antitumor activities of the synthesized compounds were tested using three different cell lines.