由n-丁和邻近的氨基氧化物衍生的混合聚合物的溶液结构和反应性
X Sun1, M D Winemiller, B Xiang
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA.
Journal of the American Chemical Society
|August 17, 2001
概括
基胺添加剂与n-丁形成混合四基体,影响对甲的反选择性添加. 特定的四聚体结构决定了反应的发生.
科学领域:
- 有机金属化学 有机金属化学
- 立体选择性合成 立体选择性合成
- 核磁共振光谱学 核磁共振光谱学
背景情况:
- n-丁 (n-BuLi) 是有机合成中的关键有机金属试剂.
- 已知化胺 (ROLi) 影响n-BuLi的反应性和选择性.
- 了解这些试剂的聚合状态是控制立体化学的关键.
研究的目的:
- 为了研究在性胺胺 (ROLi) 的存在下n-BuLi的聚合行为.
- 为了确定n-BuLi和ROLi之间形成的混合聚合物的结构.
- 为了将聚合状态与对甲的n-BuLi添加物的酶选择性相关联.
主要方法:
- 低温核磁共振 (NMR) 光谱,包括 (6) Li, (13) C 和 (15) N NMR.
- 在THF/坦溶剂混合物中制备和描述n-BuLi和各种性胺 (ROLi) 的混合物.
- 在ROLi的存在下,n-BuLi对甲的酶选择性添加反应.
主要成果:
- 形成两个不同的混合四度体:一个 (n-BuLi) ((3) ((ROLi) (3:1) 四度体和一个C ((2)) -对称的 (n-BuLi) ((2) ((ROLi) ((2) (2:2) 四度体,这取决于反应物固态度.
- 没有观察到 (n-BuLi) 的 (ROLi) 的 (n-BuLi) 的 (ROLi) 的 (ROLi) 的) 的 (n-BuLi) 的 (ROLi) 的 (ROLi) 的) 的 (ROLi) 的 (ROLi) 的) 的 (ROLi) 的 (ROLi) 的 (ROLi) 的) 的 (ROLi) 的 (ROLi) 的 (ROLi) 的 (ROLi) 的) 的 (ROLi) 的 (ROLi) 的 (ROLi) 的) 的 (ROLi) 的 (ROLi) 的) 的 (ROLi) 的 (ROLi) 的 (ROLi) 的) 的 (ROLi) 的 (ROLi) 的 (ROLi) 的) 的 (ROLi) 的 (ROLi) 的) 的 (ROLi) 的 (ROLi) 的 (ROLi) 的)
- 在将n-BuLi添加到甲基时,达到高达21:1的反体比 (反选择性),这取决于n-BuLi/ROLi比.
结论:
- n-BuLi和ROLi的固态度决定了特定的混合四度聚合物的形成.
- 这种C(2) - 对称的 (n-BuLi) (((2) ((ROLi) ((2)) 四聚体可能是负责加法反应中高反选择性的活性物种.
- 这项研究提供了关于有机化学中的立体控制机制的见解.
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