An improved synthesis of arenedicarboximides by phosphine-assisted annulation of arene-1,2-dicarbaldehyde with N-substituted maleimide

Various arene-1,2-dicarbaldehydes react with N-substituted maleimides in the presence of trialkylphosphine in refluxing dioxane to afford the title compounds in good yields, which are better than those in a similar reaction using triethylphosphite reported by Haddadin et al. Many products were isolated by direct filtration from the reaction mixtures and washing with a suitable solvent. Application of the method to synthesis of diimides is also reported.