From phosphatriafulvenes to phosphabenzenes and stable six-membered phosphaallenes

Phosphatriafulvenes readily react with kinetically stabilized phosphaalkyne s. Depending on the substituent at the phosphorus atom of the phosphatriafu lvene, different six-membered phosphaheterocycles can be isolated. On the o ne hand, 1,3-diphosphabenzenes are formed, which can be isomerized thermall y to diphospha dewarbenzenes or complexed by Cr(CO)(3). On the other hand, 1,3-diphosphaisobenzenes are thus available. They are converted to bicyclic six-membered allenes via 1,3-dipolar cycloaddition to the P/C double bond.