The Curtin–Hammett principle in action: 1-amino-3H-isoindole in cycloaddition reactions

Based on the spectral studies of 1-aminoisoindole we have observed that in solution the isoindolenine tautomer predominates. In spite of this fact but, taking into account the Curtin–Hammett principle, we undertaken the first study of the Diels–Alder reaction for 1-aminoisoindole as a typical representative of simple isoindoles in isoindoline form. We have studied the interaction of 1-aminoisoindole with maleimide derivates and demonstrated that the products are rearranged 1:2 composition adducts. We have proposed a rearrangement mechanism, detected and identified the intermediate Diels–Alder products containing both endo- and exo adducts.