Platinum(II) - Coordinated phosphinous acid-catalyzed alkylidenecyclopropanation of bicyclic alkenes with terminal alkynes

New Pt(eta(2)-acetato){[(R)(Ph)PO](2)H} complexes 3 prepared from PtCl2(CH3CN)(2) and secondary phosphine oxides (SPOs) catalyzed the [2 + 1] cycloaddition of phenylethyne (5a) with norbornene derivatives 4 to afford benzylidenecyclopropanes.