The diazotization of 2-(4-aminophenyl)acetic acid (I) by means of NaNO2 and HCl gives the diazonium salt (II), which is then condensed with 2-hydroxybenzoic acid (III) to provide the target azocompound.
The condensation of 4-nitrobenzenesulfonamide (I) with 4-chloro-4-oxobutyric acid methyl ester (II) in refluxing pyridine gives 4-(4-nitrobenzenesulfonamido)-4-oxobutyric acid methyl ester (III), which is reduced with Fe and NH4Cl in methanol/water to yield the corresponding 4-amino derivative (IV). The diazotization of (IV) with NaNO2 and HCl affords the diazonium salt (V), which is condensed with 2-hydroxybenzoic acid (VI) to provide the azo compound (VII). Finally, this compound is hydrolyzed with NaOH to the target succinamic acid derivative.