Aromative Dephosphinidenation of a Bisphosphirane-Fused Anthracene toward E−H (E=H, Si, N and P) Bond Activation

A bisphosphirane-fused anthracene (5) was prepared by treatment of a sterically encumbered amino phosphorus dichloride (3) with MgA ⋅ THF₃ (A=anthracene). X-ray diffraction analysis revealed a pentacyclic framework consisting of 5 with two phosphirane rings fused to the anthracene in a trans-fashion. Compound 5 has been shown to be an efficient phosphinidene synthon, readily liberating two transient phosphinidene units for subsequent downstream bond activation via the reductive elimination of anthracene under mild conditions. The formal oxidative addition of H₂ and E−H (E=Si, N, P) bonds by the liberated phosphinidene provided diphosphine and substituted phosphines. Furthermore, phosphinidene transfer to alkenes and alkynes smoothly yielded the corresponding phosphiranes and phosphirenes. The mechanism of the H₂ activation by 5 was investigated by density functional theory (DFT) calculations.