[N+:1]([C:4]1[CH:15]=[CH:14][C:7]([O:8][CH2:9][C:10]([NH:12][NH2:13])=[O:11])=[CH:6][CH:5]=1)([O-:3])=[O:2].[CH3:16]S(O)(=O)=O.C(OCC)(OCC)OCC.O1CCCC1>O>[N+:1]([C:4]1[CH:15]=[CH:14][C:7]([O:8][CH2:9][C:10]2[O:11][CH:16]=[N:13][N:12]=2)=[CH:6][CH:5]=1)([O-:3])=[O:2]
A mixture of 2-(4-nitrophenoxy)acetohydrazide (1.10 g), methanesulfonic acid (0.10 g), triethyl orthoformate (2.31 g) and tetrahydrofuran (50 mL) was heated under reflux for 1 hr. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed successively with saturated aqueous sodium hydrogen carbonate and saturated brine, dried over anhydrous magnesium sulfate and concentrated. The residue was subjected to silica gel column chromatography to give 2-[(4-nitrophenoxy)methyl]-1,3,4-oxadiazole as colorless crystals (0.79 g, yield 69%) from a fraction eluted with hexane-ethyl acetate (1:1, v/v). Recrystallization thereof from ethyl acetate-hexane gave colorless prism crystals. melting point: 125-126° C.
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