Folding Dendrons: The Development of Solvent-, Temperature-, and Generation-Dependent Chiral Conformational Order in Intramolecularly Hydrogen-Bonded Dendrons
Folding Dendrons: The Development of Solvent-, Temperature-, and Generation-Dependent Chiral Conformational Order in Intramolecularly Hydrogen-Bonded Dendrons
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折叠树突：分子内氢键树突中溶剂、温度和生成依赖的手性构象顺序的发展
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发表时间：
2000
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影响因子：
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通讯作者：
J. Parquette
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作者：
Janosch Recker;and Dennis J. Tomcik;J. Parquette
报道了从(1S，2S)-(+)-硫代米胺到第三代的分子内氢键树枝的合成。圆二色谱(CD)研究表明，两个非对映异构体螺旋构象(M螺旋和P螺旋)相互转化的平衡依赖于溶剂、温度和树枝状大分子的生成。CD观察到，在较差的溶剂中，随着树状大分子生成量的增加，沿树突外围的M型螺旋性的构象偏好增加。这些非对映单体螺旋构象在所研究的所有溶剂和所有温度下的第一代平衡是快速的；然而，在第二代平衡开始沿着外围偏向单一的非对映单体螺旋构象，在低温和较差的溶剂中达到最大。在第三代，螺旋偏向本质上更高，因此构象偏好…
The synthesis of intramolecularly hydrogen-bonded dendrons with stereogenic terminal groups derived from (1S,2S)-(+)-thiomicamine up to the third generation is described. Circular dichroism (CD) studies reveal that the equilibria interconverting two diastereomeric helical conformations (M and P helices) relating a pair of anthranilamide termini depends on solvent, temperature, and dendrimer generation. A conformational preference for M-type helicity along the periphery of the dendrons increased with increasing dendrimer generation and in poor solvents as observed by CD. Equilibration of these diastereomeric helical conformations is rapid at the first generation in all solvents and at all temperatures investigated; however, at the second generation the equilibrium begins to bias a single diastereomeric helical conformation along the periphery that becomes maximal at low temperatures and in poor solvents. At the third generation, the helical bias is intrinsically higher so that the conformational preference...