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

New Pt(eta2-acetato){[(R)(Ph)PO]2H} 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.