反应详情

5-bromo-3-[5-(3-methyl-2-thienyl)-1,3,4-oxadiazol-2-yl]pyrazin-2-amine (11.49 g, 33.98 mmol) and DMAP (415.1 mg, 3.398 mmol) were suspended in DCM (172.4 mL) and THF (172.4 mL) and cooled in an icebath. tert-butoxycarbonyl tert-butyl carbonate (22.24 g, 101.9 mmol) was added portionwise. The reaction mixture was allowed to warm to ambient temperature and stirred for 2 hours. The reaction mixture was filtered through plug of silica gel and concentrated in vacuo. The residue was dissolved in ethylacetate, washed with aq NaHCO3 (×1), brine (×1), dried over MgSO4 and passed through short silica gel column. The mixture was concentrated in vacuo to low bulk, diluted with petrol and stirred at 50° C. for 5 min. The mixture was filtered to give tert-butyl (5-bromo-3-(5-(3-methylthiophen-2-yl)-1,3,4-oxadiazol-2-yl)pyrazin-2-yl)carbamate as a colourless solid (16.4 g, 89%). H NMR (400.0 MHz, DMSO-d6) δ 1.4 (9H, s), 2.7 (3H, s), 7.0 (1H, d), 7.5 (1H, d), 8.7 (1H, s); LC/MS m/z 440.1 [M−100+1]+.

1. filtrationThe reaction mixture was filtered through plug of silica gel
2. concentrationconcentrated in vacuo
3. dissolutionThe residue was dissolved in ethylacetate
4. washwashed with aq NaHCO3 (×1), brine (×1)
5. dry with materialdried over MgSO4
6. concentrationThe mixture was concentrated in vacuo to low bulk
7. additiondiluted with petrol
8. stirringstirred at 50° C. for 5 min
9. filtrationThe mixture was filtered