Structurally defined potassium-mediated zincation of pyridine and 4-R-substituted pyridines (R = Et, iPr, tBu, Ph, and Me2N) by using dialkyl-TMP-zincate bases.
Structurally defined potassium-mediated zincation of pyridine and 4-R-substituted pyridines (R = Et, iPr, tBu, Ph, and Me2N) by using dialkyl-TMP-zincate bases.
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DOI：
10.1002/chem.200900549
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发表时间：
2009-07-20
影响因子：
4.3
通讯作者：
Wright, Dominic S.
中科院分区：
文献类型：
--
作者：
Clegg, William;Conway, Ben;Graham, David V.;Hevia, Eva;Kennedy, Alan R.;Mulvey, Robert E.;Russo, Luca;Wright, Dominic S.
用简单的共络合方法合成了[(pmdeta)K(μ-Et)(μ-tmp)Zn(Et)] (1) （pmdeta =N,N ',N ',N ',N ' -五甲基二乙基三胺，TMP=2,2,6,6-四甲基哌啶酯）和[(pmdeta)K(μ-nBu)(μ-tmp)Zn（nBu)](2)）两个二烷基- TMP锌酸钾碱[(pmdeta)K(μ-nBu)](2)。用一系列取代的4-R-吡啶（R=Me2N， H, Et, iPr， tBu和Ph）处理1得到2-锌的产物，其分子式为[{2- zn (Et)2-μ-4-R-C5H3N}2⋅2{K(pmdeta)}](3-8)，分离晶收率分别为53,16,7,23,67和51%；用4- tbu -吡啶处理2得到[{2- zn (nBu)2-μ-4-tBu-C5H3N}2⋅2{K(pmdeta)}](9)，分离结晶收率为58%。3-9的单晶x射线晶体学和核磁共振表征揭示了一个新的结构基序，该结构基序由一个双阴离子类二氢蒽三环体系组成，中心是一个重氮二甲酸（ZnCN）2环，两侧由pmdelta包裹的K+阳离子面盖。所有新的金属化吡啶配合物都具有这种二聚体排列。根据反应滤液的核磁共振波谱研究，产生3、7、8和9的溶液似乎基本上是干净的反应，相比之下，产生4、5和6的溶液也含有横向镀锌的副产物。在所有这些金属化反应中，锌酸钾碱作为氨基转移剂，随后的配体交换机制（氨基取代烷基）受到配位饱和度的抑制，因此，这些二聚体分子中4-配位锌中心的刘易斯酸度较低。对类似的三烷基锌酸盐试剂进行了化学计量量或亚化学计量量TMP(H)缺失和存在的研究，确定了锌- n键对有效锌化的重要性。
Two potassium–dialkyl–TMP–zincate bases [(pmdeta)K(μ-Et)(μ-tmp)Zn(Et)] (1) (PMDETA=N,N,N′,N′′,N′′-pentamethyldiethylenetriamine, TMP=2,2,6,6-tetramethylpiperidide), and [(pmdeta)K(μ-nBu)(μ-tmp)Zn(nBu)] (2), have been synthesized by a simple co-complexation procedure. Treatment of 1 with a series of substituted 4-R-pyridines (R=Me2N, H, Et, iPr, tBu, and Ph) gave 2-zincated products of the general formula [{2-Zn(Et)2-μ-4-R-C5H3N}2⋅2{K(pmdeta)}] (3–8, respectively) in isolated crystalline yields of 53, 16, 7, 23, 67, and 51%, respectively; the treatment of 2 with 4-tBu-pyridine gave [{2-Zn(nBu)2-μ-4-tBu-C5H3N}2⋅2{K(pmdeta)}] (9) in an isolated crystalline yield of 58%. Single-crystal X-ray crystallographic and NMR spectroscopic characterization of 3–9 revealed a novel structural motif consisting of a dianionic dihydroanthracene-like tricyclic ring system with a central diazadicarbadizinca (ZnCN)2 ring, face-capped on either side by PMDETA-wrapped K+ cations. All the new metalated pyridine complexes share this dimeric arrangement. As determined by NMR spectroscopic investigations of the reaction filtrates, those solutions producing 3, 7, 8, and 9 appear to be essentially clean reactions, in contrast to those producing 4, 5, and 6, which also contain laterally zincated coproducts. In all of these metalation reactions, the potassium–zincate base acts as an amido transfer agent with a subsequent ligand-exchange mechanism (amido replacing alkyl) inhibited by the coordinative saturation, and thus, low Lewis acidity of the 4-coordinate Zn centers in these dimeric molecules. Studies on analogous trialkyl–zincate reagents in the absence and presence of stoichiometric or substoichiometric amounts of TMP(H) established the importance of Zn–N bonds for efficient zincation.
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影响因子：
4.9
作者：
Conway, Ben;Graham, David V.;Mulvey, Robert E.
通讯作者：
Mulvey, Robert E.
影响因子：
16.6
作者：
Alvarez, Eleuterio;Grirrane, Abdessamad;Carmona, Ernesto
通讯作者：
Carmona, Ernesto
影响因子：
2.8
作者：
Baillie, Sharon E.;Hevia, Eva;Mulvey, Robert E.
通讯作者：
Mulvey, Robert E.
影响因子：
4.6
作者：
Cremer, U;Pantenburg, I;Ruschewitz, U
通讯作者：
Ruschewitz, U
影响因子：
3.6
作者：
Bentabed-Ababsa, Ghenla;Blanco, Fernando;Abarca, Belen
通讯作者：
Abarca, Belen