Open AccessHelical Structures of Cyclopentene-based α,α-Disubstituted α-Amino Acid Homopeptides
Author(s) -
Masakazu Tanaka,
Haruka Yakabi,
Haruki Nakatani,
Atsushi Ueda,
Mitsunobu Doi,
Makoto Oba
Publication year - 2018
Publication title -
chimia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.387
H-Index - 55
eISSN - 2673-2424
pISSN - 0009-4293
DOI - 10.2533/chimia.2018.848
Subject(s) - cyclopentene , cyclopentane , chemistry , side chain , crystallography , amino acid , stereochemistry , organic chemistry , polymer , biochemistry , catalysis
The cyclopentene-based ?,?-disubstituted ?-amino acid Ac5c= and its homopeptides, up to nonapeptides, were synthesized. The side-chain cyclopentene was expected to become symmetric, the C?-carbon to be puckered, and other C?, C?', C?, C?'-carbons to be coplanar. As expected, side-chain cyclopentene conformations became symmetric and C?-carbons were puckered. Conformational studies using FT-IR absorption, 1H NMR spectra, and X-ray crystallographic analyses revealed that Ac5c= homopeptides did not form a planar conformation, but assumed a 310-helical structure, similar to cyclopentane-based ?,?-disupstituted ?-amino acid homopeptides.