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, that 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 demetallation provides access to phosphacyclopentadienone 12.