反应详情

To a mixture of 2-(4-nitrophenoxy)acetohydrazide (1.57 g) and N,N-dimethylacetamide (50 mL) was added dropwise acetyl chloride (0.70 g) at room temperature. The reaction mixture was stirred for 2 hrs. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate and concentrated. A mixture of the obtained residue, diphosphorus pentaoxide (1.76 g), hexamethyldisiloxane (4.03 g) and 1,2-dichlorobenzene (10 mL) was stirred at 140° C. for 3 hrs. Saturated aqueous sodium hydrogen carbonate was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous magnesium sulfate and concentrated. The residue was subjected to silica gel column chromatography to give 2-methyl-5-[(4-nitrophenoxy)methyl]-1,3,4-oxadiazole as colorless crystals (0.41 g, yield 56%) from a fraction eluted with hexane-ethyl acetate (3:2-1:1, v/v). Recrystallization thereof from ethyl acetate-hexane gave colorless prism crystals. melting point: 105-106° C.

1. extractionthe mixture was extracted with ethyl acetate
2. washThe organic layer was washed with saturated brine
3. dry with materialdried over anhydrous magnesium sulfate
4. concentrationconcentrated
5. additionA mixture of the obtained residue, diphosphorus pentaoxide (1.76 g), hexamethyldisiloxane (4.03 g) and 1,2-dichlorobenzene (10 mL)
6. stirringwas stirred at 140° C. for 3 hrs
7. additionSaturated aqueous sodium hydrogen carbonate was added to the reaction mixture
8. extractionthe mixture was extracted with ethyl acetate
9. washThe organic layer was washed with saturated brine
10. dry with materialdried over anhydrous magnesium sulfate
11. concentrationconcentrated