Macrocyclic peptides, 4. Preparations and enantioface‐differentiating abilities of 27‐ and 36‐membered ring peptides containing N,N′‐ethylene‐bridged dipeptides and glycine

Abstract 27‐ and 36‐membered ring peptides were prepared using glycine, (2S, 3′ S)‐4‐methyl‐2‐(2′‐oxo‐3′‐isobutyl‐1′‐piperazinyl) pentanoic acid (2) and (2S,3′ S)‐3‐phenyl‐2‐(2′‐oxo‐3′‐benzyl‐1′‐piperazinyl)propanoic acid as the units of peptides. The interactions of 1‐phenylethylammonium (1) and p‐methoxy‐1‐phenylethylammonium bromides (11) with these cyclic peptides were studied by 1H and 13C NMR measurements in CDCl3. It was found from these results that the peptides distinguish the enantiomers (R‐ and S‐isomers) of the substrates. Furthermore, it was shown that the enantioface‐differentiating abilities of 36‐membered ring peptides are superior to those of 27‐membered rings.