89604-92-2

120-78-5

86299-47-0

89604-92-2

Synthesis of (Z)-2-(((1-(2-aminothiazol-4-yl)-2-((1-(tert-butoxy)-2-methyl-1-oxopropan-2-yl)oxy)imino)acetic acid from dibenzothiazole disulfide and (Z)-2-((2-(2-aminothiazol-4-yl)-2-(benzo[d]thiazol-2-ylthio)-2-oxoethylidene)amino)oxy) The general procedure for tert-butyl -2-methylpropanoate was as follows: 35 g of (Z)-2-(2-aminothiazol-4-yl)-2-(((1-(tert-butoxy)-2-methyl-1-oxopropan-2- yl)oxy)imino)acetic acid and 48 g of dibenzothiazole disulfide were added to a solvent mixture of dichloromethane and acetonitrile at 21 °C. (the total mass of the solvent mixture was 250 g, the density of 1.0 g/cm3). After stirring for 10 minutes, 1.0 mL of pyridine was added. At 22°C, 8.0 mL of triethylamine was slowly added. After addition, the reaction temperature was raised to 30°C and kept at this temperature for 50 minutes. Subsequently, the reaction mixture was cooled to 21 °C, and 28 mL of triethyl phosphite was slowly added dropwise at this temperature, with the dropwise addition process controlled to be completed within 2.5 hours. After the dropwise addition was completed, the reaction solution was continued at 21±1 °C for 3.0 hours. After that, the reaction mixture was cooled to 3°C and kept at this temperature for 30 minutes. Upon completion of the reaction, filtration was carried out, the solid product was collected and dried at 60 °C to afford the target product (Z)-tert-butyl 2-(((1-(2-aminothiazol-4-yl)-2-(benzo[d]thiazol-2-ylsulfanyl)-2-oxoethylidene)amino)oxy)-2-methylpropanoate in 92.6% yield and 99.3% purity.