Cyclooligomerization of a Helix-Bearing Template into Macrocycles Bearing Multiple Helices
摘要:
Cyclooligomerization was investigated for separating and spatially arranging helical peptides as discontinuous surfaces. Tetrapeptide H-[Ile-Ser-Lys(Ox)]-OH, containing a turn-inducing oxazole constraint, was connected through its lysine side chain via a beta-alanine linker to the C-terminus of a two-turn helical nonapeptide Ac-(cyclo-4,8)-LRL [KARAD](Aib). The resulting helix-appended template was self-condensed and cyclized to a library of macrocycles (n = 2-6) containing multiple (2-6) helices. An NMR structure shows retention of alpha helicity in the cyclotrimer (n = 3).
Regioselective Synthesis of Antiparallel Loops on a Macrocyclic Scaffold Constrained by Oxazoles and Thiazoles
摘要:
[GRAPHICS]The regioselective syntheses and structures are reported for two tris-macrocylic compounds, each possessing two antiparallel loops on a macrocyclic scaffold constrained by two oxazoles and two thiazoles. NMR solution structures show the loops projecting from the same face of the macrocycle. Such molecules are shown to be prototypes for mimicking multiple loops of proteins.