(Z)-2-(2-formamido-4-thiazolyl)-2-(substituted alkoxyimino) acetic acids were 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 methyl α-keto group and simultaneous cleavage of tert-butyl ester with sulfuryl chloride, protection of the obtained acid function with diphenyldiazomethane, ...