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 (300 mg, 0.92 mmol), 4-(1-hydroxypropyl)piperidine-1-carboxylic acid benzyl ester (308 mg, 1.11 mmol) and triphenylphosphine (411 mg, 1.38 mmol) in dioxane (5 mL) was added dropwise DEAD (217 ul, 1.38 mmol) and the reaction mixture was stirred at RT for 4 h. The mixture was then diluted with EtOAc and washed with NaOH aq. (1N). The organic phase was washed with brine, then dried (MgSO4) and concentrated in vacuo. The resulting residue was purified by column chromatography (Si-PCC, gradient 0-10% MeOH in EtOAc) 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]propyl}piperidine-1-carboxylic acid benzylester (280 mg, 51%). 1H NMR (CDCl3, 400 MHz): δ 8.40 (1H, d, J=8.97 Hz), 7.59 (1H, s), 7.37-7.28 (5H, m), 6.73 (1H, dd, J=8.99, 2.56 Hz), 6.54 (1H, d, J=2.52 Hz), 5.98-5.87 (1H, m), 5.14 (2H, s), 4.51-4.45 (2H, m), 4.44-4.37 (2H, m), 4.34-4.19 (2H, bs), 4.09-4.03 (1H, m), 2.83-2.68 (2H, m), 2.43 (3H, s), 1.88-1.78 (1H, m), 1.75-1.61 (5H, m), 1.58 (6H, d, J=6.65 Hz), 1.38-1.30 (1H, m), 0.97 (3H, t, J=7.37 Hz).
