@article{Tanaka_Yakabi_Nakatani_Ueda_Doi_Oba_2018, title={Helical Structures of Cyclopentene-based α,α-Disubstituted α-Amino Acid Homopeptides}, volume={72}, url={https://www.chimia.ch/chimia/article/view/2018_848}, DOI={10.2533/chimia.2018.848}, abstractNote={<p>The cyclopentene-based α,α-disubstituted α-amino acid Ac<sub>5</sub>c<sup>=</sup> and its homopeptides, up to nonapeptides, were synthesized. The side-chain cyclopentene was expected to become symmetric, the C<sup>α</sup>-carbon to be puckered, and other C<sup>β</sup>, Cβ’, C<sup>γ</sup>, C<sup>γ’</sup>-carbons to be coplanar. As expected, side-chain cyclopentene conformations became symmetric and C<sup>α</sup>-carbons were puckered. Conformational studies using FT-IR absorption, <sup>1</sup>H NMR spectra, and X-ray crystallographic analyses revealed that Ac<sub>5</sub>c<sup>=</sup> homopeptides did not form a planar conformation, but assumed a 3<sub>10</sub>-helical structure, similar to cyclopentane-based α,α-disubstituted α-amino acid homopeptides.</p>}, number={12}, journal={CHIMIA}, author={Tanaka, Masakazu and Yakabi, Haruka and Nakatani, Haruki and Ueda, Atsushi and Doi, Mitsunobu and Oba, Makoto}, year={2018}, month={Dec.}, pages={848} }