Diethyl azodicarboxylate (67 (L, 0.40 mmol) was added dropwise over 5.5 min to 3-[3-(2-methoxyphenylsulfonyloxy)-5-methylphenoxy]propanol (118 mg, 0.33 mmol, prepared in the preceding step), triphenylphosphine (106 mg, 0.40 mmol), and N-hydroxyphthalimide (55 mg, 0.33 mmol) in anhydrous tetrahydrofuran (3 mL) at 0° C. under a nitrogen atmosphere. The solution was stirred at 0° C. for an additional 20 min then at ambient temperature overnight. The reaction mixture was concentrated, and the residue was purified by flash column chromatography (dichloromethane) to give the title compound (116 mg, 69%) as a colorless resin. 1H-NMR (300 MHz, CDCl3) (7.88-7.73 (m, 5H), 7.61 (ddd, 1H, J=8.4, 7.4, 1.7 Hz), 7.10 (d, 1H, J=8.4 Hz), 7.01 (dt, 1H, J=7.7, 0.9 Hz), 6.60 (br s, 1H), 6.56, (br s, 1H), 6.42 (t, 1H, J=2.2 Hz), 4.36 (t, 2H, J=6.2 Hz), 4.09 (t, 2H, J=6.2 Hz), 4.04 (s, 3H), 2.25 (s, 3H), 2.18 (pentet, 2H, J=6.2 Hz). Mass spectrum (MALDI-TOF, α-cyano-4-hydroxycinnamic acid matrix) calcd. for C25H23NO8S: 520.1 (M+Na). Found: 520.2.
