Cycloaddition of P−C Single Bonds: Stereoselective Formation of Benzo‐1,3,6,2‐trioxaphosphepine Complexes via a Ditopic van der Waals Complex

While phosphaalkenes and phosphanes are known to participate in [4+ n ] cycloaddition reactions, P−C single bonds are inert in this respect. Herein, reactions of oxaphosphirane complexes with tetrachloro‐ ortho ‐benzoquinone are presented that reveal a stereoselective reaction of the endocyclic P−C bond to afford benzo‐1,3,6,2‐trioxaphosphepine complexes. High‐level DFT calculations provide evidence that the final product is derived from a sequence of three consecutive steps involving a ditopic van der Waals complex.