Regioselective Hydrolysis and Transesterification of Dimethyl 3‑Benzamidophthalates Assisted by a Neighboring Amide Group

An efficient, highly
regioselective hydrolysis and transesterification
of dimethyl 3-benzamidophthalates into the corresponding carboxylic
acid monoesters and mixed esters (including tert-butyl
esters) under basic conditions is presented. The selectivity is governed
by the neighboring 3-benzamido moiety’s participation and by
the nature of the solvent. In alcohols the reaction occurred exclusively
at the ortho-position to the benzamido functionality,
in pyridine or acetonitrile at both ester groups. An insight into
the mechanistic pathway was obtained from a 1H NMR study
in perdeuteromethanol.