[CH2:1]([O:3][C:4]([C:6]1[S:10][C:9]([CH3:11])=[N:8][C:7]=1[OH:12])=[O:5])[CH3:2].N12CCCN=C1CCCCC2.[CH3:24][N:25]([CH3:29])[C:26](Cl)=[S:27]>CN(C=O)C>[CH2:1]([O:3][C:4]([C:6]1[S:10][C:9]([CH3:11])=[N:8][C:7]=1[O:12][C:26](=[S:27])[N:25]([CH3:29])[CH3:24])=[O:5])[CH3:2]To a mixture of 4-hydroxy-2-methyl-thiazole-5-carboxylic acid ethyl ester (7.2 g, 37.4 mmol) and 1,8-diazabicyclo[5.4.0]undec-7-ene (11.2 ml, 74.8 mmol) in DMF (50 ml) is added N,N-dimethyl-carbamothioyl chloride (6.94 g, 56.1 mmol). The mixture is stirred at RT for 14 h and at 60° C. for 3 h, poured onto water (100 ml) and extracted with EtOAc (3×50 ml). The combined organic layers are washed with water (2×50 ml), dried over sodium sulfate and concentrated. The residue is chromatographed (silica gel, 10% EtOAc/hexane) to give 4-(dimethyl-carbamothioyl)oxy-2-methyl-thiazole-5-carboxylic acid ethyl ester (5.7 g, 20.7 mmol, 55%).
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