Reaction of functionalized pyrone with N-benzylmaleimide: study of the relevant parameters for isolation of cycloadducts

New functionalized (ketone, ester or amide) pyrones derived from coumalic acid were synthesized either by a Friedel-Craft condensation of the diphenylether or by reactions with phenols and amines. The Diels-Alder (DA) cycloaddition of these pyrones with monofunctional maleimide the N-benzylmaleimide has been studied and two parameters, temperature and solvent effects, have been investigated to control the formation of cycloadduct containing CO 2 bridge (CARAD) or decarboxylated cycloadducts (DECARAD). The pyrones and the cycloadducts were characterized by proton and carbon NMR, GC/MS and HPLC/MS. This work allowed the determination of the scope and limitation for the polyimide synthesis with bis-pyrones and bis-maleimides, which is under investigation.