Diisopropylamine → (3S,4S)-tert-butyl 3-((3-carbamoyl-6-ethynylpyrrolo[1,2-b]pyridazin-4-yl)amino)-4-ethylpyrrolidine-1-carboxylate

Participants

Reaction Steps

A mixture of (3S,4S)-tert-butyl 3-((6-bromo-3-carbamoylpyrrolo[1,2-b]pyridazin-4-yl)amino)-4-ethylpyrrolidine-1-carboxylate (330 mg, 0.730 mmol), bis(triphenylphosphine)-palladium(II) chloride (154 mg, 0.219 mmol) and copper(I) iodide (41.7 mg, 0.219 mmol) in DMF (4 mL) was stirred and degassed by bubbling nitrogen through for 15 minutes. While maintaining positive nitrogen pressure, bis(isopropyl)amine (2.58 mL, 18.24 mmol) and ethynyltrimethylsilane (0.515 mL, 3.65 mmol) were added. The flask was immediately placed in a hot oil bath at 90° C. After stirring overnight at 90° C., the reaction was complete. The reaction was then cooled to room temperature and diluted with ethyl acetate (50 mL). This mixture was filtered through Celite, and was concentrated to an oil. This crude material was suspended in MeOH (5 mL) and potassium carbonate (121 mg, 0.876 mmol) was added. After stirring the mixture at room temperature for 1 h, the insoluble solids were removed by filtration, and the resulting solution was concentrated to an oil. This crude material was purified by flash chromatography, eluting with 0-100% EtOAc in hexanes. Concentration of the pure fractions afforded a brown solid as the title compound (168 mg, 56.7% yield). 1H NMR (400 MHz, DMSO-d6) δ 11.14 (t, J=9.0 Hz, 1H), 8.27 (s, 1H), 7.96 (d, J=1.3 Hz, 1H), 7.06 (s, 1H), 4.85-4.65 (m, 1H), 4.10 (d, J=1.8 Hz, 1H), 3.73-3.54 (m, 2H), 3.43-3.24 (m, 1H), 3.08-2.92 (m, 1H), 2.44-2.26 (m, 1H), 1.55-1.43 (m, 2H), 1.36 (d, J=15.4 Hz, 9H), 0.86 (t, J=7.4 Hz, 3H). MS (ES+) m/z: 398.2 (M+H); LC retention time: 2.993 min (analytical HPLC Method O).

Provenance & Evidence