Mai Shaoyu, Li Wendong, Li Xue, Zhao Yingwei, Song Qiuling
Institute of Next Generation Matter Transformation, College of Chemical Engineering and College of Material Sciences Engineering at Huaqiao University, 668 Jimei Boulevard, Xiamen, Fujian, 361021, China.
Key Laboratory of Molecule Synthesis and Function Discovery, Fujian Province University, College of Chemistry at Fuzhou University, Fuzhou, Fujian, 350108, China.
Nat Commun. 2019 Dec 13;10(1):5709. doi: 10.1038/s41467-019-13701-5.
Cross-coupling reactions involving metal carbene intermediates play an increasingly important role in C-C bond formation. Expanding the carbene precursors to a broader range of starting materials and more diverse products is an ongoing challenge in synthetic organic chemistry. Herein, we report a Suzuki-Miyaura coupling reaction of in situ-generated Pd-carbene complexes via desulfurization of thioureas or thioamides. This strategy enables the preparation of a broad array of substituted amidinium salts and unsymmetrical diaryl ketones. The reaction is readily scalable, compatible with bromo groups on aromatic rings, tolerant to moisture and air and has a broad substrate scope. Furthermore, a single crystal structure of Pd-diaminocarbene complex is obtained and proven to be the key intermediate in both catalytic and stoichiometric reactions. Preliminary mechanistic studies demonstrate the dual role of the silver salt as a desulfurating reagent assisting the elimination of sulfur and as oxidant facilitating the Pd/Pd/Pd catalytic cycle.
涉及金属卡宾中间体的交叉偶联反应在碳-碳键形成中发挥着越来越重要的作用。将卡宾前体扩展到更广泛的起始原料和更多样化的产物是合成有机化学中一项持续存在的挑战。在此，我们报道了通过硫脲或硫代酰胺的脱硫原位生成钯-卡宾配合物的铃木-宫浦偶联反应。该策略能够制备多种取代脒盐和不对称二芳基酮。该反应易于扩大规模，与芳环上的溴基团兼容，耐潮湿和空气，并且具有广泛的底物范围。此外，获得了钯-二氨基卡宾配合物的单晶结构，并证明其是催化反应和化学计量反应中的关键中间体。初步机理研究表明，银盐作为脱硫试剂协助硫的消除以及作为促进钯催化循环的氧化剂具有双重作用。
