Synthesis and Reactivity of the Phosphorus Analogues of Cyclopentadienone, Tricyclopentanone, and Housene

The phosphorus analogues of cyclopentadienone, tricyclopentanone, and housene were accessed from bis(cyclopropenyl)diphosphetanedione 3, which was prepared by mixing 1,2,3‐tris‐tert‐butylcyclopropenium tetrafluoroborate (1) and sodium phosphaethynolate [Na(OCP)(dioxane)n]. While photolysis of 3 results in decarbonylation, yielding bis(cyclopropenyl)diphosphene 4 and after rearrangement diphosphahousene 5, thermolysis of 3 leads to phosphatricyclo[2.1.0.0]pentanone 7. Metal‐mediated valence isomerization of 7 and subsequent demetalation provides access to phosphacyclopentadienone 12. Taking the strain: The reaction of 1,2,3‐tris‐tert‐butylcyclopropenium tetrafluoroborate with sodium phosphaethynolate (NaOCP) is presented. Photolytic decarbonylation of the resulting product affords bis(cyclopropenyl)diphosphene and after rearrangement diphosphahousene, while its thermolysis provides access to phosphatricyclo[2.1.0.0]pentanone and phosphacyclopentadienone.