Blair Victoria L, Clegg William, Conway Ben, Hevia Eva, Kennedy Alan, Klett Jan, Mulvey Robert E, Russo Luca
WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, UK.
Chemistry. 2008;14(1):65-72. doi: 10.1002/chem.200701597.
Extending the recently introduced concept of "alkali-metal-mediated manganation" to functionalised arenes, the heteroleptic sodium manganate reagent [(tmeda)Na(tmp)(R)Mn(tmp)] (1; TMEDA=N,N,N',N'-tetramethylethylenediamine, TMP=2,2,6,6-tetramethylpiperidide, R=CH2SiMe3) has been treated with anisole or N,N-diisopropylbenzamide in a 1:1 stoichiometry in hexane. These reactions afforded the crystalline products [(tmeda)Na(tmp)(o-C6H4OMe)Mn(tmp)] (2) and [(tmeda)Na(tmp){o-{C(O)N(iPr)2C6H4}Mn(CH2SiMe3] (3), respectively, as determined from X-ray crystallographic studies. On the basis of these products, it can be surmised that reagent 1 has acted, at least partially and ultimately, as an alkyl base in the first reaction liberating the silane Me4Si, but as an amido base in the second reaction liberating the amine TMPH. Both of these paramagnetic products 2 and 3 have contacted ion-pair structures, the key features of which are six-atom, five-element (NaNMnCCO) and seven-atom, five-element (NaNMnCCCO) rings, respectively. Manganates 2 and 3 were successfully cross-coupled with iodobenzene under [PdCl(2)(dppf)] (dppf=1,1'-bis(diphenylphosphino)ferrocene) catalysis to generate unsymmetrical biaryl compounds in yields of 98.0 and 66.2 %, respectively. Emphasizing the importance of alkali-metal mediation in these manganation reactions, the bisalkyl Mn reagent on its own fails to metalate the said benzamide, but instead produces the monomeric, donor-acceptor complex [Mn(R)2{(iPr)2-NC(Ph)(==O)}2] (5), which has also been crystallographically characterised. During one attempt to repeat the synthesis of 2, the butoxide-contaminated complex [{(tmeda)Na(R)(OBu)(o-C6H4OMe)Mn}2] (6) was obtained. In contrast to 2 and 3, due to reduced steric constraints, this complex adopts a dimeric arrangement in the crystal, the centrepiece of which is a twelve atom (NaOCCMnC)2 ring.
将最近引入的“碱金属介导的锰化反应”概念扩展到官能化芳烃，以1:1化学计量比在己烷中用苯甲醚或N,N-二异丙基苯甲酰胺处理异核锰酸钠试剂[(tmeda)Na(tmp)(R)Mn(tmp)]（1；TMEDA = N,N,N',N'-四甲基乙二胺，TMP = 2,2,6,6-四甲基哌啶，R = CH2SiMe3）。X射线晶体学研究确定，这些反应分别得到结晶产物[(tmeda)Na(tmp)(o-C6H4OMe)Mn(tmp)]（2）和[(tmeda)Na(tmp){o-{C(O)N(iPr)2C6H4}Mn(CH2SiMe3]（3）。基于这些产物，可以推测试剂1在第一个反应中至少部分地且最终作为烷基碱释放出硅烷Me4Si，但在第二个反应中作为酰胺碱释放出胺TMPH。这两种顺磁性产物2和3都具有离子对结构，其关键特征分别是六原子五元（NaNMnCCO）环和七原子五元（NaNMnCCCO）环。锰酸盐2和3在[PdCl(2)(dppf)]（dppf = 1,1'-双（二苯基膦基）二茂铁）催化下成功与碘苯交叉偶联分别以98.0%和66.2%的产率生成不对称联芳基化合物。强调碱金属介导在这些锰化反应中的重要性，双烷基锰试剂单独无法使所述苯甲酰胺金属化，而是生成了单体供体-受体配合物[Mn(R)2{(iPr)2-NC(Ph)(==O)}2]（5），其也已通过晶体学表征。在一次重复合成2的尝试中，得到了被丁氧基污染的配合物[{(tmeda)Na(R)(OBu)(o-C6H4OMe)Mn}2]（6）。与2和3不同，由于空间位阻减小，该配合物在晶体中采取二聚体排列，其核心是一个十二原子（NaOCCMnC）2环。
