[Br:1][C:2]1[S:6][C:5]([NH:7][C:8](=[O:14])[O:9][C:10]([CH3:13])([CH3:12])[CH3:11])=[N:4][CH:3]=1.[CH:15](O)([CH3:17])[CH3:16].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.N(C(OCC)=O)=NC(OCC)=O>C1COCC1>[Br:1][C:2]1[S:6][C:5]([N:7]([CH:15]([CH3:17])[CH3:16])[C:8](=[O:14])[O:9][C:10]([CH3:11])([CH3:13])[CH3:12])=[N:4][CH:3]=1To a solution of tert-butyl 5-bromothiazol-2-ylcarbamate (3 g, 10.7 mmol), isopropanol (6.40 g, 107.4 mmol) and triphenylphosphine (5.63 g, 21.5 mmol) in THF (30 mL) was added diethyl azodicarboxylate dropwise at 0° C. The mixture was stirred at 0° C. and slowly warmed up to room temperature overnight. The solvent was evaporated. The residue was redissolved in dichloromethane (20 mL) and filtered to get rid of the undissolved solid. The filtrate was concentrated and purified by column chromatography on silica gel using 100% hexane to give a light yellow oil (3.10 g, 90% yield). LCMS (Conditions C): 4.19 min (RT); (M+H)+=267.01 (100%), 265.01 (95%), 224.95 (60%), 222.95 (60%). 1H NMR, 400 MHz, CDCl3: δ 7.34 (s, 1 H), 5.29 (m, 1 H), 1.59 (s, 9 H), 1.45 (d, 6.8 Hz, 6 H).
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