Recent Development of Biaryl Synthesis through Sigmatropic Rearrangement

Abstract

For the construction of biaryl motifs, transition metal-catalyzed cross-coupling reactions have been established as a de facto standard. However, there still remains ample room for the development of new synthetic methodologies based on a completely different reaction mechanism which can provide a rapid access to unexplored biaryl compounds. To this end, we have developed metal-free coupling reaction of aryl sulfoxides with phenols based on sigmatropic rearrangement to afford 2-hydroxy-2’-sulfanylbiaryls. Our method was successfully applied to the syntheses of intriguing aromatic molecules including oligoarenes by iterative arylations, a series of enantioenriched dihetero [8] helicenes, and polyfluorobiaryls. The method has further extended beyond the coupling of aryl sulfoxides and phenols: Phenols can be replaced with anilines and aryl sulfoxides with aryliodane, which provides 2-amino-2’-sulfanylbiaryls and 2-hydroxy-2’-iodobiaryls, respectively.