Triethylamine (1.2 ml, 8.9 mmol) followed by diphenylphosphoryl azide (1.6 ml, 7.4 mmol) was added to a solution of 4-tert-butyl hydrogen 2-(4-chlorophenylpropyl)succinate (WO 9504033 intermediate 2f) (2.4 g, 7.4 mmol) in toluene (250 ml), and the solution stirred at room temperature for 30 minutes, then under reflux for a further 3 hours. The mixture was cooled to 50° C., benzyl alcohol (2.3 ml, 22.3 mmol) added, and the reaction heated under reflux for 18 hours. The cooled mixture was concentrated under reduced pressure and the residue dissolved in ethyl acetate (125 ml). This solution was washed with saturated ammonium chloride solution (100 ml), brine (100 ml) and water (100 ml), then dried (MgSO4) and concentrated under reduced pressure. The product was purified by column chromatography on silica gel using ethyl acetate:pentane (6:94) as eluant to afford the title compound as a colourless oil 1.59 g; 1H NMR (CDCl3, 400 MHz) δ: 1.41 (s, 9H), 1.46–1.70 (m, 4H), 2.40 (m, 2H), 2.58 (m, 2H), 3.98 (m, 1H), 5.10 (s, 2H), 5.20 (d, 1H), 7.05 (d, 2H), 7.22 (m, 3H), 7.32 (m, 4H); LRMS: m/z (ES+) 454 [MNa+].
