Phosphatrioxa-adamantane

Phosphatrioxa-adamantane is an organophosphorus compound that is used as a precursor to bulky phosphine ligands. Abbreviated CgPH (for cage phosphine), it is a white solid.

The compound is prepared by the condensation of two equivalents of acetylacetone and phosphine:
 * PH3 +  2 CH3C(O)CH2C(O)CH3   →   HP(CH3CCH2CCH3)2O3  +  H2O

The condensation is sometimes called the Buckler–Epstein reaction. Many diketones can be employed in place of acetylacetone. The P-H bond can be further derivatized, leading to a range of tertiary phosphines of potential value in homogeneous catalysis.