Synthesis of macrocyclic peptidomimetics via the Ugi-click-strategy

The Ugi-click-strategy was employed for the synthesis of 12-28 membered 1,2,3-triazole derived macrocyclic peptidomimetics. The Ugi reaction with acid components bearing acetylenic fragments and azidoisocyanides provided the corresponding peptidomimetics in up to 97% isolated yield. The subsequent CuAAC click reaction with these bifunctional substrates containing both acetylene and azide groups was investigated to reveal the influence of the structure of Ugi products on the direction of the click-cyclization. It was demonstrated that this approach allows efficient synthesis of either monomeric (12- and 13-membered) or dimeric (24-, 26- and 28-membered) macrocycles prepared in up to 85% yield. The scope and limitations of this method are discussed.