X-ray crystallographic studies and comparative reactivity studies of a sodium diisopropylamide (NDA) complex and related hindered amides
X-ray crystallographic studies and comparative reactivity studies of a sodium diisopropylamide (NDA) complex and related hindered amides
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DOI：
10.1016/0022-328x(96)06203-1
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发表时间：
1996-07-12
影响因子：
2.3
通讯作者：
Wakefield, BJ
中科院分区：
文献类型：
--
作者：
Andrews, PC;Barnett, NDR;Wakefield, BJ
合成了两个由伯胺和大体积有机取代基衍生的相关的钠胺络合物，并对其进行了结晶学表征。[(Pr-I)(2)NNA(TMEDA)](2)和[Cy(Pr-I)NNA(TMEDA)](2)都采用具有中心平面(氮-金属)(2)氮杂环的二聚晶体结构，这是目前锂和钠化学中常见的特征。TMEDA配体以其通常的双齿方式进行螯合，使Na+阳离子以扭曲的四面体构型四配位。在后者中，氨基取代基相对于(NNA)(2)环平面以反式构象布置。在2-辛酮和2-甲基环己酮的选择性烯醇生成、二苯甲烷合成二苯基乙酸等一系列简单的有机反应中，前者与母体酰胺[(Pr-I)(2)NNa](无穷大)和锂同系物[(Pr-I)(2)NLi](LDA)的去质子化能力进行了比较。总的来说，钠试剂的性能优于锂试剂。
Two related sodium amide complexes derived from secondary amines with bulky organic substituents have been synthesised and crystallographically characterised. Both [(Pr-i)(2)NNa(TMEDA)](2) and [Cy(Pr-i)NNa(TMEDA)](2) adopt dimeric crystal structures with a central, planar (nitrogen-metal)(2) azametallocycle, a now familiar feature in both lithium amide and sodium amide chemistry. TMEDA ligands chelate in their usual bidentate manner making the Na+ cations four-coordinate with a distorted tetrahedral geometry. In the latter complex, the amido substituents are disposed in a trans conformation with respect to the (NNa)(2) ring plane. The deprotonating ability of the former complex has been tested against that of the parent amide [(Pr-i)(2)NNa](infinity) and the lithium congener [(Pr-i)(2)NLi](infinity) (LDA) in a series of simple organic reactions: selective enolate formation from 2-octanone and 2-methylcyclohexanone; synthesis of diphenylacetic acid via diphenylmethane. In general, the performance of the sodium reagents compares favourably with that of the lithium reagent.