The Dehydration of N-Benzyloxy and N-Hydroxymaleamic Acid and the Isomerization of N-Benzyloxyisomaleimide

Abstract

Abstract The dehydration of N-benzyloxy and N-hydroxymaleamic acids and the isomerization of N-benzyloxyisomaleimide were carried out under various conditions to obtain N-benzyloxyisomaleimide, N-hydroxyisomaleimide, and N-benzyloxymaleimide. N-substituents, such as benzyloxy, hydroxy, and acetoxy groups, depress the reactivity of nitrogen electronically and facilitate the formation of isomaleimides in the dehydration of N-substituted maleamic acids. The thermal isomerization of N-benzyloxyisomaleimide to the maleimide has been successful only in N,N-dimethylformamide. Further the conversion of isomaleimide to maleimide was performed via the addition of hydrogen bromide to isomaleimide followed by isomerization and dehydrobromination.