Cycloaddition of furfurylamines to maleic anhydride and its substituted derivatives

The regio- and stereoselectivity of the [4+2] cycloaddition of maleic, citraconic, dichloromaleic, and dibromomaleic anhydrides to difurfuryl amines and secondary furfurylamines were studied. N-Furfuryl-, N-phenyl-, and N-benzylhexahydrooxoepoxyisoindole-7-carboxylic acids were synthesized. An approach was developed for obtaining hexahydroepoxyoxoisoindole-7-carboxylic acid unsubstituted at the nitrogen atom. Aromatization of the oxabicycloheptene fragment of the dihaloepoxyiso- indolonecarboxylic acids gave a series of 7-carboxy-2-R-isoindol-1-ones.