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首页> 外文期刊>Chemistry: A European journal >Computational, ReactIR-, and NMR-Spectroscopic Investigations on the Chiral Formyl Anion Equivalent N-(#alpha#-Lithiomethylthiomethyl)-4-isopropyl-5,5-diphenyloxazolidin-2-one and Related Compounds
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Computational, ReactIR-, and NMR-Spectroscopic Investigations on the Chiral Formyl Anion Equivalent N-(#alpha#-Lithiomethylthiomethyl)-4-isopropyl-5,5-diphenyloxazolidin-2-one and Related Compounds

机译：N-（＃alpha＃-Lithiomethylthiomethyl）-4-isopropyl-5,5-diphenyloxazolidin-2-one和相关化合物的手性甲酰基阴离子当量的计算，ReactIR和NMR光谱研究

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摘要

The 4-isopropyl-3-methyl-thiomethyl-5,5-diphenyloxazolidin-2-one is readily lithiated in THF on the exocyclic CH_2 group (1->2) to give a synthetically useful chiral nucleophilic formylating reagent. We have now studied the lithiation reaction by ReactIR spectroscopy and the structure of the organolithium reagent by computational methods and by NMR-spectroscopic measurements. The lithiation is complete at -78 deg C within 90 seconds, and it is accompanied by a decrease of the C=O wavenumber by 50 cm~(-1). The NMR data (collected in [D_8]THF) give no evidence for ~(13)C,~6Li coupling or for aggregation, from DPFGSE-ROE spectra the single diastereoisomer of the lithium compound 2 seen in the NMR spectra (NMR-spectroscopic measurements from -105 to -20 deg C) is assigned like configuration; the ~(13)C=O signal of the oxazolidinone undergoes a 7 ppm down-field shift upon lithiation (1 -> 2); line-shape analyses of the signals from the diastereotopic CH_2 and CMe_2 protons in lithiated 4,4-dimethyl-3-methylthiometh-yloxazolidin-2-one (model compound 7) reveal a (triangle open)H~(++) of 8.9+-0.2 kcal mol~(-1) for enantiomerization. The theoretical calculations provide an energy-minimum structure for the lithium compound 2 with coordination of the carbonyl oxygen to lithium, with an antiperiplanar arrangement of the C,Li and S,CH_3 bonds, and with relative like configuration of the two stereocenters-in perfect agreement with the conclusions from the IR- and NMR-spectroscopic measurements!
机译：将4-异丙基-3-甲基-硫代甲基-5,5-二苯基恶唑烷丁-2-酮容易地在THF中在环外的CH_2基团上（1-> 2）进行锂化，得到合成上有用的手性亲核甲酰化试剂。我们现在已经通过反应红外光谱研究了锂化反应，并通过计算方法和核磁共振光谱测量研究了有机锂试剂的结构。锂化在90秒内在-78摄氏度下完成，并且伴随C = O波数减少50 cm〜（-1）。 NMR数据（收集在[D_8] THF中）没有提供〜（13）C，〜6Li偶联或聚集的证据，从DPFGSE-ROE光谱中可以看到，在NMR光谱中看到的锂化合物2的单一非对映异构体（NMR光谱-105至-20摄氏度的测量值）分配为类似配置;当锂化时，恶唑烷酮的〜（13）C = O信号经历了7 ppm的下场偏移（1-> 2）;锂化的4,4-二甲基-3-甲基硫代甲基-基恶唑烷-2-酮（模型化合物7）中非对映体CH_2和CMe_2质子信号的线形分析显示，H〜（++）为8.9 + -0.2 kcal mol〜（-1）用于对映异构。理论计算提供了锂化合物2的最小能量结构，其中羰基氧与锂配位，C，Li和S，CH_3键的反平面排列，并且两个立体中心的构型相对相似，完美与IR和NMR光谱测量的结论一致！

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