Rhodium/Copper Cocatalyzed Highly trans-Selective 1,2-Diheteroarylation of Alkynes with Azoles via C–H Addition/Oxidative Cross-Coupling: A Combined Experimental and Theoretical Study

Transition metal-catalyzed addition of diaryl alkynes with arylating reagents for the synthesis of tetraarylethylenes generally encounters rigorous reaction conditions and relies on the use of prefunctionalized substrates such as organic halides or surrogates and organometallic reagents. In this work, we establish a highly trans-selective 1,2-diheteroarylation of alkynes with azoles via a rhodium/copper cocatalyzed C–H addition/oxidative coupling process. Moreover, the diheteroarylation developed herein could open a door for the synthesis of heteroarene-doped tetraarylethylenes, and the photoluminescence (PL) spectra in THF–water mixtures and solid powder verify that these tetra­(hetero)­arylethylenes are aggregation-induced emission (AIE) active, building a new AIE molecule library. With a combination of experimental and theoretical methods, the reaction mechanism for addition/oxidative cross-coupling of internal alkynes with azoles has been investigated. Theoretical calculations reveal that the metalation/deprotonation of azole could occur with either rhodium or copper species. When azolylrhodium is formed, an alkyne could insert into the Rh–C bond. Another azolyl group could then transfer to rhodium from azolylcopper compound. The subsequent intramolecular trans-nucleophilic addition generates the second C–C bond. Meanwhile, the putative pathway for the formation of the hydroheteroarylated byproduct has also been explained by theoretical calculations.过渡金属催化二芳基炔烃与芳基化试剂加成合成四芳基乙烯的传统方法，通常需要严苛的反应条件，且依赖有机卤化物或其替代物、有机金属试剂等预功能化底物。本工作开发了一种基于铑/铜协同催化C-H键加成/氧化偶联过程的高反式选择性炔烃与唑类1,2-二杂芳基化反应。此外，本文所开发的二杂芳基化策略为杂芳烃掺杂的四芳基乙烯的合成开辟了新路径；通过四氢呋喃（tetrahydrofuran, THF）-水混合溶剂及固体粉末的光致发光（photoluminescence, PL）光谱表征，证实这类四(杂)芳基乙烯具有聚集诱导发光（aggregation-induced emission, AIE）活性，由此构建了全新的AIE分子库。本文结合实验与理论方法，对内炔与唑类的加成/氧化交叉偶联反应机理展开了研究。理论计算结果表明，唑类的金属化/去质子化可通过铑或铜物种介导。当形成唑基铑物种后，炔烃可插入Rh-C键中；随后另一个唑基可从唑基铜化合物转移至铑上，后续的分子内反式亲核加成则生成第二个C-C键。同时，理论计算也阐明了氢杂芳基化副产物的潜在形成路径。