Tandem cyclization: one pot regioselective synthesis of thieno[3,2-c]quinolin-4(5H)-one derivatives

A number of hitherto unreported 3-(aryloxyacetyl)-2,3-dihydro-5-alkylthieno[3,2-c]quinolin-4(5H)-ones are regioselectively synthesized in 80–90% yield from 4-(4′-aryloxybut-2′-ynyl)thioquinolin-2(1H)-ones by the oxidation with 1 equiv. of m-CPBA at 0–5°C for 1 h followed by heating under reflux in chloroform and subsequent treatment with 20% aqueous KOH. The substrate, sulfides were prepared by PTC alkylation of 4-mercaptoquinolin-2(1H)-one with 1-aryloxy-4-chlorobut-2-ynes.