Mummel Sebastian, Lederle Felix, Hübner Eike G, Namyslo Jan C, Nieger Martin, Schmidt Andreas
Clausthal University of Technology, Institute of Organic Chemistry, Leibnizstrasse 6, D-38678, Clausthal-Zellerfeld, Germany.
Fraunhofer Heinrich Hertz Institute HHI, Fiber Optical Sensor Systems, Am Stollen 19H, D-38640, Goslar, Germany.
Angew Chem Int Ed Engl. 2021 Aug 16;60(34):18882-18887. doi: 10.1002/anie.202107495. Epub 2021 Jul 14.
Sydnone methides are described from which only one single example has been mentioned in the literature so far. Their deprotonation gave anions which can be formulated as π-electron rich anionic N-heterocyclic carbenes. Sulfur and selenium adducts were stabilized as their methyl ethers, and mercury, gold as well as rhodium complexes of the sydnone methide carbenes were prepared. Sydnone methide anions also undergo C-C coupling reactions with 1-fluoro-4-iodobenzene under Pd(PPh ) and CuBr catalysis. Se NMR resonance frequencies and J as well as J coupling constants have been determined to gain knowledge about the electronic properties of the anionic N-heterocyclic carbenes. The carbene carbon atom of the sydnone methide anion 3 j resonates at δ=155.2 ppm in C NMR spectroscopy at -40 °C which is extremely shifted upfield in comparison to classical N-heterocyclic carbenes.
目前已报道了亚甲基斯德酮类化合物，然而迄今为止文献中仅提及了一个单一实例。它们的去质子化反应生成了可被描述为富π电子的阴离子型N-杂环卡宾的阴离子。硫和硒加合物以其甲基醚的形式得以稳定，并且制备了亚甲基斯德酮卡宾的汞、金以及铑配合物。在钯（三苯基膦）和溴化铜催化下，亚甲基斯德酮阴离子也会与1-氟-4-碘苯发生碳-碳偶联反应。已测定了硒的核磁共振共振频率以及耦合常数J，以了解阴离子型N-杂环卡宾的电子性质。在-40°C下进行的碳核磁共振波谱分析中，亚甲基斯德酮阴离子3 j的卡宾碳原子在δ=155.2 ppm处发生共振，与经典的N-杂环卡宾相比，该化学位移极大地移向了高场。
