[C:1]([NH:8][CH2:9][C:10]([OH:12])=O)([O:3][C:4]([CH3:7])([CH3:6])[CH3:5])=[O:2].C(=C1N=CC=N1)=O.[C:20]([NH:23][NH2:24])(=O)[CH3:21].C(Br)(Br)(Br)Br.C1C=CC(P(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1>C(Cl)Cl>[CH3:21][C:20]1[O:12][C:10]([CH2:9][NH:8][C:1](=[O:2])[O:3][C:4]([CH3:5])([CH3:6])[CH3:7])=[N:24][N:23]=1To a stirred solution of Boc-Glycine (1.75 g, 10.0 mmol) in CH2Cl2 at 0° C. was added carbonyl imidazole (1.7 g, 10.5 mmol) and the reaction was stirred for 30 min and then acetic hydrazide (740 mg, 10.0 mmol) was added. After 45 min, CBr4 (6.63 g, 20.0 mmol) and PPh3 (5.25 g, 20.0 mmol) were added and the reaction was stirred overnight at room temperature. The reaction mixture was concentrated partially and chromatographed (50% EtOAc in hexanes) to provide 2.3 g of tert-butyl (5-methyl-1,3,4-oxadiazol-2-yl)methylcarbamate with some triphenylphosphine oxide as impurity.
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