反应详情

A mixture of 2-aminooxazole-4-carboxylic acid ethyl ester (500 mg, 3.2 mmol) and acetone (2.4 mL, 32 mmol) in THF (6 mL) was stirred at rt. BH3.SMe2 (10M in THF, 0.64 mL, 6.4 mmol) was added slowly via syringe (exotherm and gas evolution were observed). AcOH (0.36 mL, 6.4 mmol) was subsequently added in the same manner. Two additional equivalents of borane and AcOH were added 18 h later. After 3 days at rt, the reaction mixture was concentrated in vacuo. The resulting residue was dissolved in EtOAc (100 mL), washed with saturated NH4Cl solution, 0.1 M NH4OH and brine. The organic phase was dried over Na2SO4 and concentrated in vacuo. The crude product was purified by flash chromatography on silica gel, eluting with EtOAc/hexane to give 2-isopropylamino-oxazole-4-carboxylic acid ethyl ester (0.40 g, 64% yield). LCMS found 199 [M+H]+.

1. concentrationthe reaction mixture was concentrated in vacuo
2. dissolutionThe resulting residue was dissolved in EtOAc (100 mL)
3. washwashed with saturated NH4Cl solution, 0.1 M NH4OH and brine
4. dry with materialThe organic phase was dried over Na2SO4
5. concentrationconcentrated in vacuo
6. customThe crude product was purified by flash chromatography on silica gel
7. washeluting with EtOAc/hexane