Application of Sulfoxonium Ylides or Iodonium Ylides in Rhodium‐Catalyzed Synthesis of Phenanthrenes

The transmetalation triggered rhodium‐catalyzed C−H bond activation and tandem annulation of 2‐biphenylboronic acids with sulfoxonium ylides or iodonium ylides has been developed. Various products of phenanthrenes were constructed under redox‐neutral conditions in 34–86% yields. Several mechanism exploration experiments and derivatization reactions were conducted in sequence to gain a deeper understanding of the process and the potential of this transformation. It offers an alternative approach for the synthesis of phenanthrene derivatives.