Synthesis of condensed heterocyclic systems based on thioindoxyl

Abstract

Substituted benzo[b]thieno[3,2-b]pyrylium salts and dibenzo[b,g]thieno[3,2-b; 2′, 3′-e′]pyrylium salts, which are converted to the corresponding pyridines on refluxing with ammonium acetate in glacial acetic acid, were synthesized by acid condensation of 3-thioindoxyl with aldehydehydes of the aromatic and heteroaromatic series in the presence of perchloric acid.