反应详情

To a solution of 3-methyl-1H-1,2,4-triazole (7.3 g, 88 mmol) in DMF (75 mL) was added K2CO3 (60.7 g, 439 mmol) and 2-bromopropionic acid tert-butyl ester (14.6 mL, 88 mmol). The reaction was stirred at room temperature overnight. The mixture was diluted with EtOAc (500 mL), washed with water (×3) then brine. Dried over MgSO4 and concentrated. The residue was purified by column chromatography on silica gel, eluting with EtOAc/isohexane (20 to 100%) to give 13 g of crude product as a 3:1 mixture of regioisomers. The mixture was purified by Chiralcel OD with a gradient from 4% to 30% IPA/Heptane. Then the first two peaks were separated with Chiracel OD column isocratically eluting with 4% IPA/Heptane. The second peak was collected as the desired single stereoisomer (R or S) (2-(3-methyl-1H-1,2,4-triazol-1-yl)propanoic acid tert-butyl ester) (3.5 g, 19%). 1H-NMR (500 MHz, CDCl3) δ 8.05 (s, 1H), 4.90 (q, J=7 Hz, 1H), 2.35 (s, 3H), 1.72 (d, J=7 Hz, 3H), 1.40 (s, 9H). ESI-MS calculated for C10H17N3O2: Exact Mass: 211.13. Found 156.05 (−tBu).

1. washwashed with water (×3)
2. dry with materialDried over MgSO4
3. concentrationconcentrated
4. customThe residue was purified by column chromatography on silica gel
5. washeluting with EtOAc/isohexane (20 to 100%)