【Chem. Eur. J. 2014, 20, 6828-6842】 下图比较形象: David W. C. MacMillan和Benjamin List因对 “不对称有机催化的发展”做出贡献获得2021年诺贝尔化学奖,除了不对称催化,David MacMillan教授还是光化学领域的知名学者。美国普林斯顿大学(Princeton University)的David W. C. MacMillan教授团队,在他们早期研究的基础上,又发展了一种在Ni/光氧化还原双催化体系下,在蓝色LED光照条件下,55℃实现低活性的氯代烷烃和氯代芳烃的还原偶联反应。作者设计了一种新型的硅烷试剂1-金刚烷氨基取代的三(三甲基硅基)硅烷3,可以克服很高的C-Cl键解离能攫取低活性氯代烷烃的氯原子,由此实现其与氯代芳香烃的还原交叉偶联【J. Am. Chem. Soc. 2020, 142, 11691–11697】。 作者又利用此方法合成了现有的一些药物,都取得了很好的产率 (51–54, 53–76% yield)。 反应操作: Procedure for optimization and control experiments Catalyst stock solution. A fresh solution was prepared for each screen by dissolving the nickel precatalyst NiCl2·glyme (11.0 mg, 0.05 mmol), 4,4',5,5'-tetramethyl-1H,1'H-2,2'-biimidazole (9.5 mg, 0.05 mmol), and Ir[(ppy)2(dtbbpy)]PF6 (9.1 mg, 0.01 mmol) in 1.0 mL DMA. This solution was sonicated until homogeneous before use. General procedure. To an oven-dried 8-mL vial equipped with a magnetic stir bar was added TMS3SiNH(Adm) (48 mg, 0.12 mmol, 1.2 equiv.), aryl chloride (e.g., 4-chlorobenzotrifluoride, 13.6 µL, 0.1 mmol, 1.0 equiv.), and alkyl chloride (e.g., 4-chlorotetrahydropyran, 21.7 µL, 0.2 mmol, 2.0 equiv.). To this reaction vial was added 50 µL tert-amyl alcohol, catalyst stock solution (150 µL; 5 mol% Ni, 1 mol% Ir), and 1,1,3,3-tetramethylguanidine (38 µL, 0.3 mmol, 3.0 equiv.). The reaction mixture was sparged with nitrogen gas for 15 minutes, and the vial was sealed with parafilm and irradiated with a 34 W Kessil H150 Blue LED from 2 cm away for 18 hours, during which the reaction temperature equilibrated at 50–55 ˚C. The reaction was quenched by exposure to air with stirring for 5 minutes. Internal standard (1,3,5-trimethoxybenzene and 1,4-difluorobenzene, 1.0 equiv.) was added to the crude reaction mixture and an aliquot was taken for 1H and 19F NMR analysis in CDCl3. Formation of the desired product was confirmed by comparing the NMR spectra with those of the independently prepared authentic product. Cross-Electrophile Coupling of Unactivated Alkyl Chlorides;Holt A. Sakai, Wei Liu, Chi “Chip” Le and David W. C. MacMillan*;J. Am. Chem. Soc. 2020, 142, 27, 11691–11697;https:///10.1021/jacs.0c04812 |
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