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首页> 外文期刊>Chemistry: A European journal >Efficient Desymmetrization of meso-cis-1, 2-Cyclohexanedimethanol with Differentiation between Diastereotopic and Enantiotopic C-H Bonds by (-)-Sparteine-Mediated Deprotonation
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Efficient Desymmetrization of meso-cis-1, 2-Cyclohexanedimethanol with Differentiation between Diastereotopic and Enantiotopic C-H Bonds by (-)-Sparteine-Mediated Deprotonation

机译：（-）-半胱氨酸介导的去质子化作用可区分非对位和对映体C-H键，从而有效地使meso-cis-1，2-环己烷二甲醇脱对称

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摘要

The deprotonation of a dicarbamate prepared from cis-1, 2-cyclohexanedimethanol by sec-butyllithium/(-)-sparteine proceeds with efficient selection between the enantiotopic branches and their diastereotopic protons with high preference for the pro-S proton at the R branch to afford the intermediate, configurationally stable lithium compound as a single diastereomer. Trapping of this intermediate by electrophiles (DOMe, CO_2, CH_3I, Me_3SiCl, or R_3SnCl) takes place with retention of the configuration to yield highly enantiomerically and diastereomerically enriched substitution products, which are easily converted to diols, to anellated tetrahydrofurans, or to #gamma#-lactones. The chiral base is also capable of efficient kinetic resolution of the racemic #alpha#-deuterated starting material, by the utilization of an extraordinarily high kinetic H/D isotope effect within the deprotonation step. The, presumably, first example of the kinetic resolution of a racemic stannane by lithiodestannylation, utilizing methyllithium/(-)-sparteine, is reported.
机译：由仲丁基锂/（-）-天冬氨酸对由顺式1，2-环己烷二甲醇制得的二氨基甲酸酯进行质子化，可以在对映体支链及其非对映体质子之间进行高效选择，其中R分支的pro-S质子优先于得到作为单一非对映异构体的中间结构稳定的锂化合物。通过亲电子试剂（DOMe，CO_2，CH_3I，Me_3SiCl或R_3SnCl）捕获该中间体，并保留了构型，以生成高度对映体和非对映体富集的取代产物，这些取代产物易于转化为二醇，芳基化的四氢呋喃或#gamma ＃-内酯。通过在去质子化步骤中利用极高的动力学H / D同位素效应，手性碱还能够有效地消旋外消旋α-α-氘代的起始原料。据报道，这是利用甲基锂/（-）-天冬氨酸通过硫代脱锡反应动力学拆分外消旋锡烷的第一个例子。

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