Herein, we describe a straightforward, thiol-free palladium-catalyzed umpolung protocol that uses mild conditions to stitch together readily available dibromoolefins and disulfides, yielding a diverse array of 2-sulfenyl benzofused heterocycles. Upon insertion of Zn into disulfide, in situ generated zinc thiolate engaged in a tandem cyclization/functionalization squence as a viable thiolation agent. In contrast to the existing methods that rely on sophisticated manipulations to prepare starting materials, this technique features high efficiency, synthesis simplicity, commercial availability of reagents, and a broad substrate scope.
Zheng et al. (Tue,) studied this question.