Reaction Steps
PMe3 (1.0 M solution in THF) (0.95 mL, 0.95 mmol) was added dropwise to a solution of 3-(azidomethyl)-6-(2,6-difluorophenyl)pyridazine (Preparation I, 235 mg, 0.95 mmol) in THF (6.0 mL) at RT. The reaction turned purple and an evolution of gas was observed. The reaction was stirred for 15 min at RT. A solution of tert-butyl ((3R,4R,5S)-4-((tert-butyl(dimethyl)silyl)oxy)-1-(3-isothiocyanato-4-pyridinyl)-5-methyl-3-piperidinyl)carbamate (Preparation XIII, 455 mg, 0.95 mmol) in THF (5.0 mL) was added. After 15 min at RT, the mixture was diluted with EtOAc and washed with brine. The aqueous phase was extracted with EtOAc (2×). The combined organic layers were dried over anh. Na2SO4, filtered and concentrated. The crude material was purified by silica gel chromatography (0-3% MeOH in CH2Cl2) to provide tert-butyl ((3R,4R,5S)-4-((tert-butyl(dimethyl)silyl)oxy)-1-(3-((2-(2,6-difluorophenyl)imidazo[1,5-b]pyridazin-7-yl)amino)-4-pyridinyl)-5-methyl-3-piperidinyl)carbamate (450 mg, 0.68 mmol, 71% yield) as an orange solid. MS (ESI, pos. ion) m/z: 666.3 (M+1). 1H NMR (400 MHz, CDCl3) δ ppm 9.76 (s, 1 H), 8.21 (d, J=5.09 Hz, 1 H), 7.77 (d, J=9.39 Hz, 1H), 7.70 (br. s., 1 H), 7.34-7.47 (m, 2 H), 7.05 (t, J=8.12 Hz, 2 H), 6.93 (d, J=5.28 Hz, 1H), 6.51 (d, J=9.39 Hz, 1 H), 4.49 (br. s., 1 H), 3.67 (br. s., 1 H), 3.40 (d, J=10.76 Hz, 1H), 3.14-3.28 (m, 2 H), 2.81 (t, J=10.07 Hz, 1 H), 2.29 (t, J=11.15 Hz, 1 H), 1.89-2.03 (m, 1 H), 1.40 (br. s., 9 H), 0.93 (s, 12 H), 0.11 (d, J=11.15 Hz, 6 H).
