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One‐Handed Helical Screw Direction of Homopeptide Foldamer Exclusively Induced by Cyclic α‐Amino Acid Side‐Chain Chiral Centers
Author(s) -
Demizu Yosuke,
Doi Mitsunobu,
Kurihara Masaaki,
Maruyama Tokumi,
Suemune Hiroshi,
Tanaka Masakazu
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201102902
Subject(s) - side chain , asymmetric carbon , chemistry , crystallography , stereochemistry , helix (gastropod) , foldamer , amino acid , tartaric acid , salt (chemistry) , optically active , organic chemistry , ecology , biochemistry , snail , citric acid , biology , polymer
Chiral cyclic α,α‐disubstituted amino acids, (3 S ,4 S )‐ and (3 R ,4 R )‐1‐amino‐3,4‐(dialkoxy)cyclopentanecarboxylic acids (( S , S )‐ and ( R , R )‐Ac 5 c dOR ; R: methyl, methoxymethyl), were synthesized from dimethyl L ‐(+)‐ or D ‐(−)‐tartrate, and their homochiral homoligomers were prepared by solution‐phase methods. The preferred secondary structure of the ( S , S )‐Ac 5 c dOMe hexapeptide was a left‐handed ( M ) 3 10 helix, whereas those of the ( S , S )‐Ac 5 c dOMe octa‐ and decapeptides were left‐handed ( M ) α helices, both in solution and in the crystal state. The octa‐ and decapeptides can be well dissolved in pure water and are more α helical in water than in 2,2,2‐trifluoroethanol solution. The left‐handed ( M ) helices of the ( S , S )‐Ac 5 c dOMe homochiral homopeptides were exclusively controlled by the side‐chain chiral centers, because the cyclic amino acid ( S , S )‐Ac 5 c dOMe does not have an α‐carbon chiral center but has side‐chain γ‐carbon chiral centers.