New Synthetic Approach to o -Ketobenzoic Pseudo-Acid Chlorides

A new approach has been developed for the synthesis of o -ketobenzoic pseudo-acid chlorides via dehalogenation of bromo-substituted cyclic o -ketobenzoic acid esters, followed by chlorination of the resulting diesters. Homocoupling of 2-(4-bromobenzoyl)benzoic acid methyl ester gave bis-pseudo-acid chloride con­taining a biphenyl fragment, which could not be obtained by the traditional method involving acylation of biphenyl and subsequent chlorination of the diacid thus formed owing to deactivation of the second para -position in the aromatic fragment. The proposed approach solves the problem of poor solubility of poly­phenylene diacids with more than three phenylene rings and makes it possible to synthesize a bis-pseudo-acid chloride with a quaterphenyl fragment.