(R)-(+)-[VCD(-)984]-4-Ethyl-4-methyloctane: A Cryptochiral Hydrocarbon with a Quaternary Chiral Center. (2) Vibrational CD Spectra of Both Enantiomers and Absolute Configurational Assignment
(R)-(+)-[VCD(-)984]-4-Ethyl-4-methyloctane: A Cryptochiral Hydrocarbon with a Quaternary Chiral Center. (2) Vibrational CD Spectra of Both Enantiomers and Absolute Configurational Assignment
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(R)-( )-[VCD(-)984]-4-乙基-4-甲基辛烷：具有四级手性中心的隐手性烃。
DOI：
10.1002/ejoc.201000778
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发表时间：
2010
影响因子：
2.8
通讯作者：
N. Harada
中科院分区：
文献类型：
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作者：
S. Kuwahara;K. Obata;Takuma Fujita;Nobuaki Miura;A. Nakahashi;K. Monde;N. Harada
为了准确表征4-乙基-4-甲基辛烷（1）的手性性质，合成了对映体（S）-（-）-[VCD（+）984]-1。在365 nm处观察到的两种对映体的比旋光度值一致，但符号相反，证实了它们的对映体关系，尽管它们的绝对值非常小，反映了它们的隐手性。两种对映体的振动圆二色性（VCD）光谱在1150-900 cm-1附近显示出特征的Cotton效应，VCD光谱曲线互为镜像。根据（S）-（-）-1在984 cm-1处观察到的正VCD带，其绝对构型完全指定为（S）-（-）-[VCD（+）984]-1。用DFT MO方法在B3 PW 91/6- 31 G（d，p）水平上对（S）-1的VCD谱进行了量子化学计算，计算得到的VCD曲线与（S）-（-）-1的VCD谱符合得很好，证实了（S）-（-）-1的绝对构型.
To characterize precisely the chiroptical properties of 4-ethyl-4-methyloctane (1), one of the so-called cryptochiral compounds, the enantiomer (S)-(-)-[VCD(+)984]-1 was synthesized in an enantiopure form. The observed specific rotation values at 365 nm of both enantiomers agreed well, but were opposite in sign, confirming their enantiomeric relationship, although their absolute values were very small, reflecting their cryptochirality. The vibrational circular dichroism (VCD) spectra of both enantiomers were measured neat and showed characteristic Cotton effects around 1150-900 cm -1 ; the VCD spectral curves were mirror images of each other. Based on the observed positive VCD band at 984 cm -1 for (S)-(-)-1, its absolute configuration was fully designated as (S)-(-)-[VCD(+)984]-1. The VCD spectrum was quantum chemically calculated by the DFT MO method at the B3PW91/6-31G(d,p) level, and the simulated VCD curve for (S)-1 agreed very well with the observed VCD spectrum of (S)-(-)-1, confirming the absolute configuration.
( R )-( )-[VCD( )945]-4-乙基-4-甲基辛烷，最简单的具有四级立构中心的手性饱和烃
DOI：
--
发表时间：
2007
期刊：
影响因子：
--
作者：
Takuma Fujita;K. Obata;S. Kuwahara;Nobuaki Miura;A. Nakahashi;K. Monde;John D. Decatur;N. Harada
通讯作者：
N. Harada