反应详情

A 60% dispersion of NaH (75 mg, 1.9 mmol) was added to a stirred solution of (S)-tert-butyl 2-(6-bromo-1H-imidazo[4,5-b]pyrazin-2-yl)pyrrolidine-1-carboxylate (627 mg, 1.70 mmol) in DMF (15 mL) and the reaction was stirred for 1.5 h at room temperature. Then SEM-Cl (0.30 mL, 1.7 mmol) was added and the reaction was stirred overnight. The reaction was diluted with water (˜30 mL) and EtOAc (˜35 mL), the layers were separated and the organic layer was washed with brine (30 mL), dried (MgSO4), filtered and concentrated. The crude yellow oil was purified by flash chromatography (40 g SiO2, 20-30% EtOAc/hexanes) to yield (S)-tert-butyl 2-(5-bromo-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-imidazo[4,5-b]pyrazin-2-yl)pyrrolidine-1-carboxylate (421 mg) as a clear colorless oil and (S)-tert-butyl 2-(6-bromo-1-((2-(trimethylsilyl)ethoxy)methyl)-1H-imidazo[4,5-b]pyrazin-2-yl)pyrrolidine-1-carboxylate (345 mg) as a clear colorless oil. The absolute regiochemistry of the SEM group was not established unambiguously, the names (and structures) may be exchanged in these intermediates.

1. stirringthe reaction was stirred overnight
2. customthe layers were separated
3. washthe organic layer was washed with brine (30 mL)
4. dry with materialdried (MgSO4)
5. filtrationfiltered
6. concentrationconcentrated
7. customThe crude yellow oil was purified by flash chromatography (40 g SiO2, 20-30% EtOAc/hexanes)