[H-].[Na+].[NH2:3][C:4]1[S:5][CH:6]=[C:7]([CH2:9][C:10]([O:12][CH2:13][CH3:14])=[O:11])[N:8]=1.[CH:15](OCC)=[O:16].[C:20](O)(=[O:22])C>CCCCCC.O1CCCC1>[CH:15]([CH:9]([C:7]1[N:8]=[C:4]([NH:3][CH:20]=[O:22])[S:5][CH:6]=1)[C:10]([O:12][CH2:13][CH3:14])=[O:11])=[O:16]
Under nitrogen, 14 g (0.29 mmol) of 50% NaH in oil was washed with 2×40 ml of hexane and then suspended in 90 ml of anhydrous tetrahydrofuran (THF). To this slurry at 0° C. was added dropwise a solution of ethyl 2-(2-amino-4-thiazolyl)acetate (27 g, 0.145 mmol) in 290 ml of anhydrous THF, followed by ethyl formate (21.5 g, 0.29 mmol), and the mixture stirred at room temperature for 18 hours. The pH of reaction mixture was adjusted to 7 by the addition of 50% aqueous acetic acid and the mixture extracted with 250 ml ethyl acetate. The aqueous layer was further extracted with 2×50 ml of 1:1 THF:ethyl acetate. The extracts were combined, dried over Na2SO4 and evaporated to a solid, which was recrystallized from ethyl acetate to yield purified title product, 17.8 g (50.7%); m.p. 179°-180° C.; 1H-nmr (CDCl3 -d6 -DMSO) 1.33 (t, 3H), 4.16 (q, 2H), 7.50 (s, 1H), 8.00 (s, 1H), 8.53 (s, 1H).
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