To a suspension of 2-(2-isopropyl-5-methyl-2H-[1,2,4]triazol-3-yl)-4,5-dihydro-6-oxa-1,3a-diazabenzo[e]azulen-8-ol from Example 4 (400 mg, 1.23 mmol), 4-(1-hydroxyethyl)piperidine-1-carboxylic acid benzyl ester (487 mg, 1.85 mmol) and triphenylphosphine (548 mg, 2.09 mmol) in dioxane (7 mL) was added dropwise DIAD (410 ul, 2.09 mmol) and the reaction mixture was stirred at RT for 18 h. The mixture was then diluted with EtOAc and washed with aq. NaOH (1N). The aqueous phase was extracted with EtOAc (×3) and the combined organic layers were then washed with brine, dried over MgSO4 and concentrated in vacuo. The resulting residue was purified by column chromatography (Si-PCC, gradient 0-10% MeOH in EtOAc), then suspended in DCM and filtered. The filtrate was concentrated in vacuo and purified by column chromatography (Si-PCC, gradient 0-10% MeOH in DCM) affording 4-{1-[2-(2-Isopropyl-5-methyl-2H-[1,2,4]triazol-3-yl)-4,5-dihydro-6-oxa-1,3a-diazabenzo[e]azulen-8-yloxy]ethyl}piperidine-1-carboxylic acid benzyl ester (140 mg, 20%). LCMS: RT 3.90 min [M+H]+ 571.0
