Sodium Hydroxide → 4-(((3S,4S)-1-(tert-butoxycarbonyl)-4-methylpyrrolidin-3-yl)amino)-3-carbamoylpyrrolo[1,2-b]pyridazine-6-carboxylic acid

Participants

Reaction Steps

A mixture of ethyl 4-(((3S,4S)-1-(tert-butoxycarbonyl)-4-methylpyrrolidin-3-yl)amino)-3-carbamoylpyrrolo[1,2-b]pyridazine-6-carboxylate (585 mg, 1.356 mmol) and NaOH, 1N (3.39 mL, 3.39 mmol) in THF (14 mL) was stirred at rt for 4 days. At the end of each day, additional NaOH, 1N (3.39 mL, 3.39 mmol) was added, for a total of three additions. The reaction mixture was partitioned between ˜70 ml of EtOAc and 50 ml of water. While stirring the biphasic mixture, the pH was adjusted to ˜2 with saturated KHSO4 solution. The layers were separated and the aqueous layer was extracted with DCM (50 ml). A precipitant began to form in the combined organic layer. The solid was very fine and the suspension was dried over Na2SO4. The supernate was decanted off and the sodium sulfate was thoroughly rinsed with hot EtOAc and hot MeOH. The decanted supernates were concentrated to afford 4-(((3S,4S)-1-(tert-butoxycarbonyl)-4-methylpyrrolidin-3-yl)amino)-3-carbamoylpyrrolo[1,2-b]pyridazine-6-carboxylic acid (545 mg, 1.351 mmol, 100% yield) as a tan solid. 1H NMR (400 MHz, DMSO-d6) δ 12.51 (br. s., 1H), 11.23 (br. s., 1H), 8.32 (s, 1H), 8.07 (d, J=1.3 Hz, 1H), 7.19 (d, J=1.3 Hz, 1H), 4.76 (d, J=15.0 Hz, 1H), 3.83-3.51 (m, 2H), 3.40-3.34 (m, 1H), 3.09-2.87 (m, 1H), 2.58 (d, J=7.5 Hz, 1H), 1.37 (d, J=13.2 Hz, 9H), 1.13-0.86 (m, 3H). MS (ES+) m/z: 304.2 (M+H-Boc); LC retention time: 2.533 min (analytical HPLC Method O).

Provenance & Evidence