Sulfoxide-tethered alkyne

The synthesis of dihydrobenzothiepinone 80 by a previously reported gold-catalyzed oxidation of sulfoxide-tethered alkyne 77 was the subject of a detailed experimental and theoretical mechanistic study (13JA8512).A theoretical study showed that the previously proposed mechanism involving benzothiepine formation by a Friedel—Crafts cyclization onto an oxo-car-bene 81 is unlikely and that a [3,3]-sigmatropic rearrangement of the first cyclization intermediate 78 is more favorable. 

Taking advantage of a tandem sulfoxide elimination-sulfenic acid addition approach to cyclic sulfoxides <1977J(P1)1574>, the synthesis of a number of novel 1,4-oxathiane oxides 229 and 230 based on the intramolecular addition of sulfenic acids to alkenes or alkynes tethered through an ether linkage has been reported (Equation 38) <20050BC404>. 

---