Abstract: A process is disclosed to produce a carboxylic acid derivative of the general formula VIII!: ##STR1## wherein R.sup.1, R.sup.2, R.sup.3 and L are each as defined in the specification, characterized in that a benzyl halide is reacted with a cyano compound to give a phenylacetonitrile, which is then reacted with an alkyl nitrite in the presence of a base to give an .alpha.-hydroxyiminophenylacetonitrile, which is then reacted with an alkylating agent to give an .alpha.-alkoxyiminophenylacetonitrile, which is then hydrolyzed in the presence of a base, or is hydrated and treated with an acid, followed by hydrolysis in the presence of a base, to give an .alpha.-alkoxyiminophenylacetic acid, which is then reacted with an acid halide forming agent, or is convened into a metal salt, followed by reaction with an alkylating agent, or is reacted with a lower alcohol in the presence of an acid catalyst.