Thioester derivatives are important intermediates in biochemical reactions and serve as useful synthetic reagents for CC formations. 1) Thiolenone, unsaturated cyclic thioester, has been a target for structural and reactivity studies, because of the similarlity of its tautomer, hydroxy ... thiophene, to phenol. 2) In connection with our preparative study on 4-substituted furanone3 ) and pyrrolone,4) and as a result of reports concerning antitumor activity associated with ...