Base-Catalyzed Addition and Solvolysis Reactions of N-Phenylmaleimide in Methanol

The base-catalyzed reaction of methanol with N-phenylmaleimide provides mainly methyl α-methoxysuccinanilate (III), which is formed from the intermediate methyl maleanilate (II). The course of the reaction was followed gas chromatographically, and the role of various possible intermediates is discussed. Observations concerning the relative thermal stabilities of III and its β-methoxy isomer (IV) are also presented. Nuclear magnetic resonance spectra were recorded for III, N-phenyl-α-methoxysuccinimide (V), and dimethyl α-methoxysuccinate (VI), all of which exhibit ABX-type patterns. Calculations carried out on the spectrum of V indicated Jax, Jbx, and Jab to be 7.85, 4.5, and 18.4 c.p.s., respectively.