| 摘要 |
The invention relates to a process for the preparation of acids of general formula <IMAGE> in which R1 and R3 represent hydrogen, a C1-C5 alkyl radical optionally substituted by an aryloxy group, a C2-C5 alkenyl radical, a cycloalkyl radical, an aryl radical or an aralkyl radical, and R2 represents one of the radicals defined for R3 above, according to which process: - in a first stage, a carbanion is formed by reacting a carboxylic acid, in the form of an alkali metal salt, with lithium diethylamide in an aromatic hydrocarbon; - in a second stage, the said carbanion is reacted with a suitable halide in an aromatic hydrocarbon; - then, the desired acid is released by reacting with a strong acid.
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