Assignment of the absolute configuration of alpha-chiral carboxylic acids by 1H NMR spectroscopy
Assignment of the absolute configuration of alpha-chiral carboxylic acids by 1H NMR spectroscopy
复制标题
通过 1H NMR 光谱确定 α-手性羧酸的绝对构型
DOI：
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发表时间：
2000
影响因子：
3.6
通讯作者：
R. Riguera
中科院分区：
文献类型：
--
作者：
M. Ferreiro;S. Latypov;E. Quiñoá;R. Riguera
本文讨论了由α-手性羧酸与（R）-和（S）-2-羟基-2-（9-蒽基）乙酸乙酯[（R）-和（S）-9-AHA，5]的酯的~ 1H NMR谱预测其绝对构型的方法。低温NMR实验，MM，半经验，和芳香族屏蔽效应计算允许的主要构象的识别，并表明，在所有的酯研究，构象AP是最稳定的。本文提出了一个由NMR数据确定绝对构型的简单模型，并用已知绝对构型的酸6-31证实了该模型的可靠性。除5外，还研究了其它具有开放（32-38）和环状（39-42）结构的辅助试剂。发现反式-（+）-和（-）-2-苯基-1-环己醇（41）特别有效并产生类似于5的Δ Δ RS值。
The prediction of the absolute configuration of alpha-chiral carboxylic acids from the 1H NMR spectra of their esters with (R)- and (S)-ethyl 2-hydroxy-2-(9-anthryl) acetate [(R)- and (S)-9-AHA, 5] is discussed. Low-temperature NMR experiments, MM, semiempirical, and aromatic shielding effect calculations allowed the identification of the main conformers and showed that, in all esters studied, conformer ap is the most stable. A simple model for the assignment of the absolute configuration from NMR data is presented, and its reliability is corroborated with acids 6-31 of known absolute configuration. In addition to 5, other auxiliary reagents with open (32-38) and cyclic (39-42) structures have also been studied. trans-(+)- and (-)-2-phenyl-1-cyclohexanol (41) was found to be particularly efficient and produced delta delta RS values similar to those of 5.