反应详情

A solution of tetrabutylammonium fluoride (1M in THF) (4.27 mL, 4.27 mmol) was added in one portion to a stirred solution of (S)-2-(tert-butyldimethylsilyloxy)-3-ethoxy-N-(5-methylpyrazin-2-yl)propanamide (Intermediate H2) (1.45 g, 4.27 mmol) in tetrahydrofuran (25 mL). The resulting solution was stirred at ambient temperature for 4 hours. The reaction mixture was concentrated and diluted with EtOAc (50 mL) washed sequentially with water (20 mL) and saturated brine (20 mL). The organic layer was dried (MgSO4) and evaporated. The residue was purified by flash silica chromatography eluting with 50% to 100% EtOAc in isohexane to afford (2S)-3-ethoxy-2-hydroxy-N-(5-methylpyrazin-2-yl)propanamide (700 mg, 73%). 1H NMR (400 MHz, CDCl3) δ 1.24 (3H, t), 2.54 (3H, s), 3.49 (1H, d), 3.61 (2H, q), 3.75-3.83 (2H, m), 4.35-4.39 (1H, m), 8.14 (1H, d), 9.13 (1H, s), 9.43 (1H, d); m/z (ESI+) (M+H)+=226; HPLC tR=1.00 min.

1. concentrationThe reaction mixture was concentrated
2. additiondiluted with EtOAc (50 mL)
3. washwashed sequentially with water (20 mL) and saturated brine (20 mL)
4. dry with materialThe organic layer was dried (MgSO4)
5. customevaporated
6. customThe residue was purified by flash silica chromatography
7. washeluting with 50% to 100% EtOAc in isohexane