Under a nitrogen atmosphere, 60% sodium hydride (200 mg), 1-bromo-2-triphenylmethoxyethane (1.84 g) and tetraisopropyl methylenebisphosphonate (1.72 g) were suspended in toluene (5 ml), and the resulting suspension was stirred at 120° C. for 7 hours. The reaction mixture was diluted with toluene, and then a saturated aqueous ammonium chloride solution was added thereto to decompose the excess sodium hydride. Then, ethyl acetate was added thereto to effect separation, and the organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was purified by a silica gel column chromatography (chloroform:acetone) to obtain 1,1-bis(diisopropoxyphosphinoyl)-3-triphenylmethoxypropane (2.44 g, yield 77%).
