| 摘要 |
<p>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).</p> |
