Regioselective reductions of various 3-aminosuccinimides; Application to the synthesis of two heterocyclic systems.

The synthesis of novel pyrrolo[3,2-c]isoquinolines is investigated starting from 3-aminosuccinimides. Various known routes leading to 3-aminosuccinimides were tested but a new approach via nucleophilic addition of arylalkylamines on maleimide gave better results. The regioselectivity of the reduction of these compounds was shown to depend on the degree of substitution of the concerned 3-aminosuccinimide. The hydroxylactams are formed in-situ, then converted into the ethoxylactams. The latter, after generation of an iminium salt, afforded the target pyrroloisoquinolines and two further derivatives of another new heterocyclic system: the 3,6-methano-2,5-benzodiazocine. (C) 1997, Elsevier Science Ltd.