1-Hydroxybenzotriazole → 2-{(2S,3S)-2-[(R)-2-tert-butoxycarbonylamino-2-(2,3-dihydro-benzo[1,4]dioxin-6-yl)-acetylamino]-3-phenyl-butyrylamino}-thiazole-4-carboxylic acid methyl ester

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반응 단계

2-((2S,3S)-2-Amino-3-phenyl-butyrylamino)-thiazole-4-carboxylic acid methyl ester (0.255 g, 0.80 mmol), (2R)-tert-butoxycarbonylamino-(2,3-dihydro-benzo[1,4]dioxin-6-yl)-acetic acid (prepared according to the procedure of Bohme, E. H. W. et al., J. Med. Chem. 1980, 23,405-412), O-benzotriazol-1-yl-N,N,N′,N′-tetramethyluronium hexaflurorophosphate (0.364 g, 0.96 mmol) and diisopropylethyl amine (0.56 mol, 3.2 mmol) were dissolved in N,N-dimethylformamide (3 mL) in an ice bath. 1-Hydroxybenzotriazole (0.13 g, 9.6 mmol) in N,N-dimethylformamide (1 mL) was added dropwise. Stirring was continued for 30 min at 0° C. The reaction mixture was diluted with ethyl acetate and the mixture was washed with water and brine. The organic layer was diluted with an equal volume of dichloromethane, filtered through a pad of silica gel with a layer of sodium sulfate on the top and eluted with 1:1 ethyl acetate/dichloromethane. Evaporation of the solvents gave a white solid which was triturated with ether/hexane to give crude 2-{(2S,3S)-2-[(R)-2-tert-butoxycarbonylamino-2-(2,3-dihydro-benzo[1,4]dioxin-6-yl)-acetylamino]-3-phenyl-butyrylamino}-thiazole-4-carboxylic acid methyl ester (0.49 g).

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