Gold-catalyzed cycloisomerization of sulfur ylides to dihydrobenzothiepines.

The metal-promoted nucleophilic addition of sulfur ylides to electronically poor pi-systems is a well-studied reactivity. However, the driving force of such transformations, elimination of a sulfide moiety, entails stoichiometric byproducts making them unfavorable in terms of atom economy. Herein, we report on a new take on sulfur ylide chemistry, an atom-economical gold(I)-catalyzed synthesis of dihydrobenzo[ b ]thiepines. The reaction proceeds under mild conditions at room temperature from readily accessible sulfonium ylides.