Construction of 6H-benzo[c]thiochromenes via a tandem reaction of arynes with thionoesters†
Abstract
A mild and transition-metal free tandem reaction for the construction of 6H-benzo[c]thiochromenes has been developed. Thionoesters react with two molecules of arynes through a Diels–Alder cycloaddition/nucleophilic arylation process to afford 6-alkoxy-6-aryl-6H-benzo[c]thiochromenes in 37–80% yields. In addition, the Diels–Alder cycloaddition/aromatization tandem reaction of thionoesters with one molecule of aryne provides the construction of 6-alkoxyl-6H-benzo[c]thiochromenes in 51–75% yields.