Gold‐Catalyzed Cycloisomerization of Sulfur Ylides to Dihydrobenzothiepines

The metal‐promoted nucleophilic addition of sulfur ylides to π‐systems is a well‐established reactivity. However, the driving force of such transformations, elimination of a sulfide moiety, entails stoichiometric byproducts making them unfavorable in terms of atom economy. In this work, a new take on sulfur ylide chemistry is reported, an atom‐economical gold(I)‐catalyzed synthesis of dihydrobenzo[b]thiepines. The reaction proceeds under mild conditions at room temperature.