Synthesis of (Z)-2-(2-formamido-4-thiazolyl)-2-(substituted alkoxyimino) acetic acids

(Z)-2-(2-formamido-4-thiazolyl)-2-(substituted alkoxyimino) acetic acids we re synthesized by a new method based on the following sequence of reactions : treatment of the tert-butyl acetoacetate with sodium nitrite, alkylation of the oxime formed with an appropriate alkyl halide, halogenation of methy l alpha-keto group and simultaneous cleavage of tert-butyl ester with sulfu ryl chloride, protection of the obtained acid function with diphenyldiazome thane, formation of the 2-aminothiazole ring by the Hantzsch method with th iourea, formylation of the amino group and selective final cleavage of the diphenylmethyl eater by treatment with trifluoroacetic acid and anisol. The developed procedure allows the synthesis of (Z)-2-(2-formamido-4-thiazolyl )-2(substituted alkoxyimino) acetic acids, with an ester function in the al koxyimino group employing a simple method and obtaining higher yields in co mparison with the habitually used classic method. (C) 2000 Elsevier Science S.A. All rights reserved.