Indian Institute of Technology, Kharagpur, 721302, India.
Chemistry. 2020 Feb 11;26(9):1922-1927. doi: 10.1002/chem.201904761. Epub 2020 Jan 21.
The synthesis of a diverse range of heterobiaryls has been achieved by a transition-metal-free sp -sp cross-coupling strategy using lithiated heterocycle, aryl or heteroaryl boronic ester and an electrophilic halogen source. The construction of heterobiaryls was carried out through electrophilic activation of the aryl-heteroaryl boronate complex, which triggered 1,2-migration from boron to the carbon atom. Subsequent oxidation of the intermediate boronic ester afforded heterobiaryls in good yield. A comprehensive B NMR study has been conducted to support the mechanism. The cross coupling between two nucleophilic cross coupling partners without transition metals reveals a reliable manifold to procure heterobiaryls in good yields. Various heterocycles like furan, thiophene, benzofuran, benzothiophene, and indole are well tolerated. Finally, we have successfully demonstrated the gram scale synthesis of the intermediates for an anticancer drug and OLED material using our methodology.
通过无过渡金属的 sp-sp 交叉偶联策略，使用锂化杂环、芳基或杂芳基硼酸酯和亲电卤源，实现了多种杂联芳烃的合成。杂联芳烃的构建是通过芳基-杂芳基硼酸酯配合物的亲电活化来进行的，这引发了硼到碳原子的 1,2-迁移。随后，中间硼酸酯的氧化得到了杂联芳烃，产率良好。进行了全面的 B NMR 研究以支持该机理。两种亲核交叉偶联试剂之间的交叉偶联，无需过渡金属，为获得高产率的杂联芳烃提供了可靠的途径。各种杂环，如呋喃、噻吩、苯并呋喃、苯并噻吩和吲哚，都能很好地耐受。最后，我们成功地展示了使用我们的方法进行抗癌药物和 OLED 材料中间体的克级合成。
