| 摘要 |
PURPOSE:To obtain a cephalosporin derivative useful as a medicine advantageously, by eliminating only the phenacyl ester part at the 4-position with a mineral or sulfonic acid and zinc in an inert solvent without converting the heterocyclic ring thiomethyl group at the 3-position. CONSTITUTION:A compound of formulaI(R<1> is H or acyl; R<2> is H or methoxyl; R<3> is formula II or S-heterocyclic ring; R<4> is H or halogen; X is S, O or methylene), e.g. phenacyl 7beta-cyanomethylthioacetamido-7alpha-methoxy-3-(1-methyl-1H- tetrazol-5-yl)tiomethyl-3-cephem-4-carboxylate, is reacted with zinc and a mineral or sulfonic acid in an inert solvent, preferably hydrous acetone, to give a compound of formula III. The amount of the zinc to be used is 1-2 times that of the raw ester. The reaction temperature is -50-+5 deg.C, preferably -30-+20 deg.C. |
