Citric Acid → 6-((6-Bromo-[1,2,4]triazolo[4,3-a]pyridin-3-yl)difluoromethyl)imidazo[1,2-b]pyridazine-2-carbonyl azide

Participants

Reaction Steps

To a stirred solution of 6-((6-bromo-[1,2,4]triazolo[4,3-a]pyridin-3-yl)difluoromethyl)imidazo[1,2-b]pyridazine-2-carboxylic acid (3.5 g, 8.55 mmol), N-ethyl-N-isopropylpropan-2-amine (6.63 g, 51.3 mmol) and sodium azide (5.56 g, 86 mmol) in anhydrous DMF (60 mL), PyBOP (5.34 g, 10.27 mmol) was added in portions at ambient temperature over 5 min. The reaction was stirred for an additional 30 min and diluted with EtOAc (200 mL). The reaction was then poured into a 10% aqueous citric acid (200 mL), and the organic phase was separated and washed with citric acid solution (2×100 mL), saturated NaHCO3 (3×100 mL), and saturated NaCl solution. The aqueous phases were back extracted with EtOAc (200 mL) and the organic phases were combined, dried with MgSO4, filtered, and concentrated to dryness via rotary evaporation. The resulting residue was triturated in 1:1 Et2O/hexane, and the solid was collected by filtration and dried in vacuum over P2O5 to provide the title compound, 6-((6-bromo-[1,2,4]triazolo[4,3-a]pyridin-3-yl)difluoromethyl)imidazo[1,2-b]pyridazine-2-carbonyl azide 45K (3.2 g, 7.37 mmol, 92%). 1H NMR (400 MHz, DMSO-d6) δ ppm 7.77 (dd, J=9.85, 1.77 Hz, 1 H) 7.88 (d, J=9.60 Hz, 1 H) 8.00-8.05 (m, 1 H) 8.56 (d, J=9.60 Hz, 1 H) 8.98 (s, 1 H) 9.14 (s, 1 H). ESI-MS:m/z 434.0 (M+H)+. ESI-MS:m/z 406.0 (M+H)+.

Provenance & Evidence