Methyl 6-[(3-benzyloxy-5-hydroxybenzoyl)amino]-3-pyridinecarboxylate(2.20 g, 5.81 mM), triphenylphosphine (1.59 g, 6.10 mM), iso-propanol (0.445 ml, 5.81 mM) and THF (50 ml) were combined and diisopropylazodicarboxylate (1.2 ml, 6.10 mM) was added dropwise. The reaction was stirred for 72 hours at ambient temperature. The mixture was concentrated in vacuo and the resulting brown oil was purified by column chromatography on Kieselgel 60, eluting with a gradient of 50–100% methylene chloride in iso-hexane and then 5% EtOAc in methylene chloride to give methyl 6-[(3-benzyloxy-5-isopropoxybenzoyl)amino]-3-pyridinecarboxylate as a colourless oil (1.92 g); H1 NMR δ (d6-CDCl3) 1.36 (6H d) 3.95 (3H s) 4.60 (1H sept) 5.09 (2H s) 6.72 (1H s) 7.02 (1H s) 7.10 (1H s) 7.30–7.50 (4H m) 8.39 (2H ddd) 8.68 (1H s br) 8.92 (1H s). [M+H] 421; [M-H] 419.
