Alkylidene malonamides and acetacetamides as intermediates for the preparation of constrained dipeptide mimetics.

On the basis of our previous experience in the synthesis of alkylidene malonates and acetoacetates, we turned our attention to the microwave assisted Knövenagel reaction leading to alkylidene malonamides and acetoacetamides. In particular we prepared derivatives of a-aminoester, that may be envisaged as useful intermediates in the synthesis of constrained dipeptide mimetics. The presence of a reactive double bond offers indeed the opportunity to perform conjugate additions of nitrogen nucleophiles or allylic substitutions on the corresponding reduced derivatives. Through these protocols, novel structures containing an a-amino ester linked to a b-amino acid derivative have been obtained. These building blocks may be properly functionalized to mimick ligands of biologically relevant receptors or coupled to form oligomers, with the aim to verify their possible application as secondary structures inducers.