Synthesis of 1,2,3‐Triphospholenes, 1,2‐Diphosphetes, and Unsymmetric Phospholes by Rhodium‐catalyzed Cleavage of P−P Bonds and Addition to Alkynes.

The rhodium‐catalyzed addition reaction of cyclo‐(PPh)5 to alkynes in refluxing THF efficiently provide 1,2,3‐triphospholenes, in which the –PPh–PPh–PPh– group is transferred from cyclo‐(PPh)5 by the cleavage of P−P bonds. In refluxing chlorobenzene, the reactions are accompanied by the formation of 1,2‐diphosphetes. When the triphospholenes containing P−P bonds are reacted with reactive alkynes under rhodium‐catalyzed conditions, unsymmetric phospholes are obtained. The rhodium‐catalyzed reactions can be used to synthesize various phosphorus‐containing heterocycles with different numbers of phosphorus atoms. [ABSTRACT FROM AUTHOR]