Multicomponent Approach to Bioactive Peptide–Ecdysteroid Conjugates : Creating Diversity at C6 by Means of the Ugi Reaction

An efficient multicomponent protocol has been developed to access two different kinds of peptide–ecdysteroid conjugates. The approach exploits the reactivity of the 6-keto-7-ene group of 20-OH-ecdysone, allowing the unprecedented preparation of 6-amino and 6-isocyanide derivatives. The ecdysteroid derivatives were further employed in the Ugi reaction, together with formaldehyde and various structurally diverse carboxylic acids, isocyanides and amines, to afford a small family of potential multidrug-resistance modulators.