Oxalyl chloride (2.1 mL, 24.0 mmol) was added to a solution of 3-[(1S)-2-methoxy-(1-methylethyl)oxy]-5-{[phenylmethyl]oxy}benzoic acid (6.32 g, 20.0 mmol) in DCM (100 mL) and the mixture stirred at RT for 4 hours. The mixture was evaporated in vacuo to a residue, which was taken up in DCM (25 mL) and added to a stirred mixture of 2-amino-5-methylpyrazine (2.29 g, 21.0 mmol) and pyridine (1.94 mL, 24.0 mmol) in DCM (100 mL) at 5° C.-10° C. The mixture was stirred at RT for 18 hours, the DCM evaporated in vacuo. The residue was partitioned between water (50 mL) and ethyl acetate (150 mL), the organic layer washed with brine, dried (MgSO4) and evaporated to a residue, which was chromatographed on silica, eluting with 50% ethyl acetate in isohexane, to give the desired compound (7.0 g). 1H NMR δ (CDCl3): 1.3 (d, 3H), 2.5 (s, 3H), 3.3 (s, 3H), 3.4-3.5 (m, 2H), 4.5 (m, 1H), 5.0 (s, 2H), 6.7 (s, 1H), 7.0 (s, 1H), 7.05 (s, 1H), 7.35 (m, 5H), 8.05 (s, 1H), 8.3 (s, 1H) and 9.5 (s, 1H). m/z 408 (M+H)+.
