N[C:2]1[N:7]=[C:6]2[O:8][C:9]([C:11]3[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=3)=[N:10][C:5]2=[CH:4][CH:3]=1.[N+]([O-])(OCCC(C)C)=O.[CH:26]1[CH:31]=[CH:30][CH:29]=[CH:28][CH:27]=1>>[C:11]1([C:9]2[O:8][C:6]3[C:5]([N:10]=2)=[CH:4][CH:3]=[C:2]([C:26]2[CH:31]=[CH:30][CH:29]=[CH:28][CH:27]=2)[N:7]=3)[CH:16]=[CH:15][CH:14]=[CH:13][CH:12]=1A mixture of 180 mg. of 5-amino-2-phenyloxazolo[ 5,4-b]pyridine, 10 ml. of benzene and 0.2 ml. of isoamyl nitrate was refluxed for 11/2 hours. The hot solution was filtered and concentrated to dryness. The residue was extracted with ether and the extract was filtered through aluminum oxide and concentrated to dryness. The crystalline residue was recrystallized from ethyl acetate to give 2,5-diphenyloxazolo[ 5,4-b]pyridine, m.p. 151°-152° C.
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