反应详情

温度

0 °C

1,1-Dimethylethyl 4-[(hydroxyamino)(imino)methyl]piperazine-1-carboxylate (3.58 g, 14.6 mmol) was suspended in THF (50 mL) followed by the addition of diisopropylethylamine (3.0 mL, 17.5 mmol) and the mixture was cooled to 0° C. Acetoxyacetyl chloride (1.6 mL, 14.6 mmol) was added by syringe and the mixture was allowed to stir an additional 30 minutes at 0° C. The resulting homogeneous solution was allowed to warm to room temperature then concentrated in vacuo to afford a white solid residue. The material was suspended in water (50 ml) and the solid product was collected by filtration, washed with additional water then hexanes and dried in vacuo. The intermediate O-acyl derivative was then suspended in THF (50 mL) followed by addition of TBAF (1.0M in THF, 3.5 mL) and the mixture was stirred for 30 minutes at room temperature. The homogeneous solution obtained was concentrated in vacuo and the residue partitioned with ethyl ether and water. The organic layer was washed twice with additional water then with saturated aqueous sodium chloride and dried over anhydrous magnesium sulfate. Filtration and concentration gave 1,1-dimethylethyl 4-{5-[(acetoxy)methyl]-1,2,4-oxadiazol-3-yl}piperazine-1-carboxylate (3.6 g, 76% yield) as a colorless crystalline solid. 1H-NMR (400 MHz, CDCl3): 5.14 (s, 2H), 3.51 (tr, 4H), 3.42 (tr, 4H), 2.18 (s, 3H), 1.48 (s, 9H).

1. temperatureto warm to room temperature
2. concentrationthen concentrated in vacuo
3. customto afford a white solid residue
4. filtrationthe solid product was collected by filtration
5. washwashed with additional water
6. dry with materialhexanes and dried in vacuo
7. additionfollowed by addition of TBAF (1.0M in THF, 3.5 mL)
8. stirringthe mixture was stirred for 30 minutes at room temperature
9. customThe homogeneous solution obtained
10. concentrationwas concentrated in vacuo
11. customthe residue partitioned with ethyl ether and water
12. washThe organic layer was washed twice with additional water
13. dry with materialwith saturated aqueous sodium chloride and dried over anhydrous magnesium sulfate
14. filtrationFiltration and concentration