Uncatalysed intermolecular aza-Michael reactions

The catalyst-free reactions of activated alkenes with primary and secondary amines were investigated leading to various mono- and di-hydroamination products, the latter being rare and original. These reactions were shown to depend first on the strength of the nucleophile. Temperature and steric hindrance of the reagents were the other key factors controlling the selectivity of these aza-Michael reactions. In spite of their poor nucleophilicities, some N-heterocyclic amines could react with different activated alkenes affording valuable intermediates. Such results tended to demonstrate the hydrogen-bonding interactions between activated alkenes and poly-nitrogen aromatic cycles may control these concerted or fully conjugate aza-Michael additions.