According to a similar procedure to that described in Example 4-(5), 1-oxo-1,3-dihydroisobenzofuran-6-carbonitrile (1.66 g, 10.5 mmol) obtained from Example 5-(2) was reacted with an aqueous solution of sodium hydroxide (1.008N; 10.38 ml, 10.46 mmol), 4-methoxybenzyl chloride (1.64 g, 10.5 mmol), tetrazole (1.47 g, 20.9 mmol), bis(allyloxy)(diisopropylamino)phosphine (Tetrahedron Lett., 30, 4219 (1989); 3.68 g, 15 mmol), and tert-butyl hydroperoxide (80% di-tert-butyl peroxide solution; Merck; 2.7 g, 24 mmol), and the reaction mixture was worked up to afford, after extraction, a residue as a mixture of a solid (starting material) and an oil. The residue was washed with a mixed solvent of ethyl acetate-hexane, and the washings were concentrated to give a residue. The residue was subjected to chromatography on a silica gel (40 g) column (eluent; ethyl acetate:hexane=1:1˜3:2) to afford a mixture of a solid and an oily material. The mixture was washed further with a mixed solvent of ethyl acetate-hexane, and the washings were concentrated to give a residue. The residue was subjected to chromatography on a silica gel (40 g) column (eluent; ethyl acetate:hexane=2:3) to afford the title compound (737.9 mg, 15% yield) as a colorless oil.
