Synthesis and Reactivity of 3-Methylsulfinyl-2H-cyclohepta[b]furan-2-ones

2H-Cyclohepta[b]furan-2-ones (2a,b) reacted with dimethyl sulfide dittiflate to give dimethy](2-oxo-2H-cyclohepta[b]furan-3-yl)sulfonium trifluoromethanesulfonates (3a,b), which were treated with Et3N to give 3-methylthio-2H-cyclohepta[b]furan-2-ones (4a,b). Sulfides 4a and 4b were oxidized with m-CPBA to give corresponding sulfoxides (5a,b) and sulfones (6a,b). The sulfoxides (5a,b) thermally underwent coupling reaction to give 3,3'-bi-2H-cyclohepta[b] furan-2-ones (7a,b). The sulfoxides (5a,b) reacted with trifluoromethanesulfonic anhydride (Tf2O) to afford sulfonium ions 8a and 8b at lower temperature, which reacted with 2a or 2b to give sulfonium ions (9a-c). Treatment of compounds 9a-c with Et2NH or Et3N gave corresponding sulfide products (10a-c).