Electrochemical Annulation of ortho‐Alkynylbiphenyls to Fused Sulfenyl Phenanthrenes and Spiro Cyclohexenone Indenes

Abstract Here, we present an electrochemically induced synthesis of 9‐sulfenylarylphenanthrenes and 3’‐sulfenylarylspiro‐cyclohexa[4.5]trienones starting from o ‐alkynylbiphenyls and diaryl disulfides. This method was accomplished through constant current electrolysis of 10 mA in an undivided cell setup by utilizing CH 3 CN as a solvent and LiClO 4 as an electrolyte at room temperature. Notably, the present strategy enabled the formation of sulfenylphenanthrenes and sulfenyl spiro cyclohexa[4.5]trienones in 70%–95% yield. Scale‐up synthesis, mechanistic studies, and cyclic voltammetry have also been carried out.