Helical Structures of Bicyclic<i>α</i>-Amino Acid Homochiral Oligomers with the Stereogenic Centers at the Side-Chain Fused-Ring Junctions
作者:Kosuke Anan、Yosuke Demizu、Makoto Oba、Masaaki Kurihara、Mitsunobu Doi、Hiroshi Suemune、Masakazu Tanaka
DOI:10.1002/hlca.201200403
日期:2012.10
Chiral bicyclic α‐amino acid (R,R)‐Ab5,6=c with stereogenic centers at the γ‐position of fused‐ring junctions, and its enantiomer (S,S)‐Ab5,6=c, were synthesized. The CD spectra of (R,R)‐Ab5,6=c oligomers indicated that the (R,R)‐Ab5,6=c hexapeptide formed a mixture of right‐handed (P)‐ and left‐handed (M)‐310‐helices, while, in the (R,R)‐Ab5,6=c nonapeptide, a right‐handed (P)‐310‐helix slightly dominated
合成了手性双环α-氨基酸(R,R)-Ab 5,6 = c,在稠合环连接的γ位置具有立体中心,及其对映体(S,S)-Ab 5,6 = c 。(R,R)-Ab 5,6 = c低聚物的CD谱表明(R,R)-Ab 5,6 = c六肽形成右手(P)和左手(M)3 10螺旋,而在(R,R)-Ab 5,6 = c九肽,右旋(P)-3 10螺旋在(M)螺旋上略占优势。X射线晶体学分析(S,S)-三肽和(R,R)-六肽,表明三肽和六肽分别形成(P)-和(M)-3 10螺旋的混合物。这些结果表明,立体异构中心周围的侧链环境对于控制折叠器的螺旋拧紧性特别重要。