2-Lithio-3,3-dimethyl-2-oxazolinyloxirane: Carbanion or Azaenolate? Structure, Configurational Stability, and Stereodynamics in Solution
作者:Vito Capriati、Saverio Florio、Renzo Luisi、Filippo Maria Perna、Agnese Spina
DOI:10.1021/jo801646e
日期:2008.12.19
-130 degrees C. Despite this, Li-1 exhibited an unusual thermal stability undergoing a successfully deuterium incorporation (>98%) also at 25 degrees C with a little decomposition. The structure, configurational stability, and stereodynamics in solution of alpha-lithiated oxazolinyloxirane Li-1 have been also synergically investigated by means of in situ IR and NMR spectroscopy. IR spectroscopic studies
化学研究表明,在醚类溶剂中,氧杂环丁基锂Li-1在低温(175 K)下无论是宏观(霍夫曼教科书)还是微观时间尺度上都是结构不稳定的。光学纯的恶唑啉基环氧乙烷1样品一旦去质子化,即可在-130℃下于THF / Et(2)O(3:2)(t(1/2)= 6.05 s)中在1分钟内消旋。Eyring方程的应用表明在-130℃下8.8 kcal / mol的Li-1转化的障碍。尽管如此,Li-1在25℃成功掺入氘时仍表现出异常的热稳定性(> 98%)摄氏度有一点分解。还通过原位IR和NMR光谱协同研究了α-锂化恶唑啉基环氧乙烷Li-1溶液的结构,构型稳定性和立体动力学。红外光谱研究表明1的锂化在-98摄氏度下在1分钟内完成,并且伴随着CN波数仅减少60 cm(-1),因此支持了Li-1的结构可能是更类似于“有机锂”而不是“氮杂甲酸酯”。除此之外,多核磁共振研究表明,至少在0.08-0.3 M的浓度范