Conformational studies on peptides having chiral five-membered ring amino acid with two azido or triazole functional groups within the sequence of Aib residues
作者:Makoto Oba、Naomi Kawabe、Hiroomi Takazaki、Yosuke Demizu、Mitsunobu Doi、Masaaki Kurihara、Hiroshi Suemune、Masakazu Tanaka
DOI:10.1016/j.tet.2014.09.086
日期:2014.11
The chiral cyclic alpha,alpha-disubstituted alpha-amino acid, (3R,4R)-1-amino-3,4-diazido-1-cyclopentanecarboxylic acid [(R,R)-Ac-5C(dN3)], was introduced into achiral alpha-aminoisobutyric acid (Aib) peptides. The azido groups of (R,R)-Ac-5C(dN3) in the peptides were efficiently converted into 1,2,3-triazole functional groups. FTIR, H-1 NMR, and CD spectra revealed that the dominant conformations of all peptides in solution were 3(10)-helical structures without controlling the helical-screw sense. X-ray crystallographic analyses of peptides containing (R,R)-Ac-5C(dN3) showed that both the right-handed (P) and left-handed (M) 3(10)-helical structures were present in the crystal state. (C) 2014 Elsevier Ltd. All rights reserved.