Pye Dominic R, Cheng Li-Jie, Mankad Neal P
Department of Chemistry , University of Illinois at Chicago , 845 W. Taylor St. , Chicago , IL 60607 , USA . Email:
Chem Sci. 2017 Jul 1;8(7):4750-4755. doi: 10.1039/c7sc01170a. Epub 2017 Mar 31.
A bimetallic system consisting of Cu-carbene and Mn-carbonyl co-catalysts was employed for carbonylative C-C coupling of arylboronic esters with alkyl halides, allowing for the convergent synthesis of ketones. The system operates under mild conditions and exhibits complementary reactivity to Pd catalysis. The method is compatible with a wide range of arylboronic ester nucleophiles and proceeds smoothly for both primary and secondary alkyl iodide electrophiles. Preliminary mechanistic experiments corroborate a hypothetical catalytic mechanism consisting of co-dependent cycles wherein the Cu-carbene co-catalyst engages in transmetallation to generate an organocopper nucleophile, while the Mn-carbonyl co-catalyst activates the alkyl halide electrophile by single-electron transfer and then undergoes reversible carbonylation to generate an acylmanganese electrophile. The two cycles then intersect with a heterobimetallic, product-releasing C-C coupling step.
由铜卡宾和锰羰基共催化剂组成的双金属体系用于芳基硼酸酯与卤代烷的羰基化C-C偶联反应,可实现酮的汇聚合成。该体系在温和条件下运行,对钯催化表现出互补的反应活性。该方法与多种芳基硼酸酯亲核试剂兼容,对于伯烷基和仲烷基碘亲电试剂均能顺利进行反应。初步机理实验证实了一种假设的催化机理,该机理由相互依赖的循环组成,其中铜卡宾共催化剂参与金属转移以生成有机铜亲核试剂,而锰羰基共催化剂通过单电子转移活化卤代烷亲电试剂,然后进行可逆羰基化以生成酰基锰亲电试剂。然后,这两个循环与一个异双金属的、释放产物的C-C偶联步骤相交。