WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL (UK).
Angew Chem Int Ed Engl. 2015 Nov 16;54(47):14075-9. doi: 10.1002/anie.201507586. Epub 2015 Sep 29.
Herein the sodium alkylmagnesium amide [Na4Mg2(TMP)6(nBu)2] (TMP=2,2,6,6-tetramethylpiperidide), a template base as its deprotonating action is dictated primarily by its 12 atom ring structure, is studied with the common N-heterocyclic carbene (NHC) IPr [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene]. Remarkably, magnesiation of IPr occurs at the para-position of an aryl substituent, sodiation occurs at the abnormal C4 position, and a dative bond occurs between normal C2 and sodium, all within a 20 atom ring structure accommodating two IPr(2-). Studies with different K/Mg and Na/Mg bimetallic bases led to two other magnesiated NHC structures containing two or three IPr(-) monoanions bound to Mg through abnormal C4 sites. Synergistic in that magnesiation can only work through alkali-metal mediation, these reactions add magnesium to the small cartel of metals capable of directly metalating a NHC.
本文研究了钠烷基镁酰胺[Na4Mg2(TMP)6(nBu)2]（TMP=2,2,6,6-四甲基哌啶），其中模板碱的去质子作用主要由其 12 原子环结构决定。该研究采用了常见的 N-杂环卡宾（NHC）IPr [1,3-双(2,6-二异丙基苯基)咪唑-2-亚基]。值得注意的是，IPr 的镁化发生在芳基取代基的对位，钠化发生在异常的 C4 位置，并且在容纳两个 IPr(2-)的 20 原子环结构中，正常的 C2 与钠之间形成了配位键。通过研究不同的 K/Mg 和 Na/Mg 双金属碱，得到了另外两种含有两个或三个通过异常 C4 位点与 Mg 键合的 IPr(-)单阴离子的镁化 NHC 结构。这些反应通过碱金属介导协同作用，使得镁能够加入到能够直接使 NHC 金属化的少数几种金属之列。
