TMSCl‐Mediated Carbocyclization‐Phosphorothiolation of Alkynes to Access Phosphorothiolated Phenanthrene and 2 <i>H</i> ‐Chromene Derivatives

A practical and mild strategy for TMSCl‐mediated electrophilic carbocyclization–phosphorothiolation of alkynes with N ‐phosphorothiosuccinimide has been developed. This method enables efficient access to a wide range of fused phosphorothiolated phenanthrene and 2 H ‐chromene derivatives in 61–86% yields from readily available o ‐alkynylbiphenyls and but‐1‐yne‐1,4‐diyldibenzenes, showcasing a broad substrate scope. Notably, o ‐alkynylbiphenyls bearing electron‐rich OMe groups undergo a phosphorothiolation/dearomatization process to deliver phosphorothiolated spiro‐cyclohexa[4.5]trienones. The utility of this protocol is further demonstrated through scale‐up synthesis and the introduction of a SP(O)(OR) 2 motif into bioactive molecule derivatives.