A useful intermediate for synthesizing antibacterials (i.e., 1-(2-protected amino-4-thiazolyl)propene-1,3-dicarboxylic acid half ester (VI)) is prepared by a process comprising 1) treating haloacetylmalonic acid ester (i) with thiourea to give 2-(2-amino-4-thiazolyl)malonic acid ester (II), 2) protecting the amino group of the latter to give 2-(2-protected amino-4-thiazolyl)malonic acid ester (III), 3) treating the product with haloalkenoic acid ester to give 1-(2-protected amino-4-thiazolyl)-2-propene-(1,1,3-tri or 1,1,3,3-tetra)carboxylic acid ester (IV), 4) hydrolyzing and decarboxylating the latter to give 1-(2-protected amino-4-thiazolyl)propene-1,3-dicarboxylic acid (V), and 5) treating the product with alcohol and a hemi-esterifying reagent to give the objective 1-(2- protected amino-4-thiazoly)propene-1,3-dicarboxylic acid half ester (VI).
一种用于合成抗菌剂的有用中间体(即 1-(2-保护
氨基-4-
噻唑基)
丙烯-1,3-二
甲酸半酯 (VI)1-(2-保护
氨基-4-
噻唑基)
丙烯-1,3-二
羧酸半酯(VI))的制备过程包括 1)用
硫脲处理卤乙酰
丙二酸酯(i),得到 2-(2-
氨基-4-
噻唑基)
丙二酸酯(II)、2) 保护后者的
氨基,得到 2-(2-保护
氨基-4-
噻唑基)
丙二酸酯 (III), 3) 用卤代烯酸酯处理该产物,得到 1-(2-保护
氨基-4-
噻唑基)-2-
丙烯-(1、(1,1,3-三或 1,1,3,3-四)
羧酸酯 (IV),4) 将后者
水解和脱羧,得到 1-(2-保护
氨基-4-
噻唑基)
丙烯-1,3-二
羧酸 (V),5) 用醇和半酯化试剂处理产物,得到目的 1-(2-保护
氨基-4-
噻唑基)
丙烯-1,3-二
羧酸半酯 (VI)。