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不含金属的光化学Borylation芳基卤化物

Charlo威廉^*

*通信:

Charlo威廉
印度期刊编辑部,有机化学
电子邮件: (电子邮件保护)

文摘

Arylboronic酸和酯广泛用于化工、制药、和材料科学。他们灵活的创造碳碳合成纤维或在有机化学合成杂原子债券。反应arylmetallic中间体的三烃基硼酸盐,其次是transesterication或水解,是传统生产arylboron化合物的过程。这些反应有几个很大的局限性,包括限制官能团容忍和严格的无水条件下的要求。过渡金属催化borylation过程包括钯、镍、铜和锌了非常有用的方式将cx债券转换为cb债券在最近几十年[1]。基于过渡金属催化剂的直接碳氢键borylation技术最近已经开发出来。几个transition-metal-free cb债券综合开发方法,以减少成本和重金属残留在最终产品的数量。伊藤和他的同事们表明,碱溶液alkoxide-mediated borylation芳基卤化物可以通过使用一个silylborane作为唯一borylating试剂[1,4]。张先生和他的同事们发现,芳基碘化可以borylated reuxing甲醇与4.0版的bis (pinacolato) diboron和2.0版的Ce2CO3启动子。反应时间从几小时到几天不等,中等收益[2,3]。 Under mild circumstances, Fernandes and Muniz converted diaryliodonium acetates to arylboronates.

介绍

Arylboronic酸和酯广泛用于化工、制药、和材料科学。他们灵活的创造碳碳合成纤维或在有机化学合成杂原子债券。反应arylmetallic中间体的三烃基硼酸盐,其次是transesterication或水解,是传统生产arylboron化合物的过程。这些反应有几个很大的局限性,包括限制官能团容忍和严格的无水条件下的要求。过渡金属催化borylation过程包括钯、镍、铜和锌了非常有用的方式将cx债券转换为cb债券在最近几十年[1]。基于过渡金属催化剂的直接碳氢键borylation技术最近已经开发出来。几个transition-metal-free cb债券综合开发方法,以减少成本和重金属残留在最终产品的数量。伊藤和他的同事们表明,碱溶液alkoxide-mediated borylation芳基卤化物可以通过使用一个silylborane作为唯一borylating试剂[1,4]。张先生和他的同事们发现,芳基碘化可以borylated reuxing甲醇与4.0版的bis (pinacolato) diboron和2.0版的Ce2CO3启动子。反应时间从几小时到几天不等,中等收益[2,3]。 Under mild circumstances, Fernandes and Muniz converted diaryliodonium acetates to arylboronates. Wang invented a mild and efficient Sandmeyer-type borylation process using aryl amines as the starting material. 8a–c Aryl diazonium salts8d–f and aryl triazenes8g have also been observed to be borylated. Furthermore, new procedures for direct C– H borylation under transition metal-free conditions have been reported9, however the substrates were limited to electron-rich arenes or heterocycles, and air and moisture sensitive reagents were required [4]. As a result, a practical, metal-free approach that is quick and successful, operates under mild circumstances with a variety of easily accessible borylating reagents, has a high functional group tolerance, and avoids strong acids, bases, and dangerous chemicals remains highly desirable. We present here our invention and development of a new aryl halide borylation reaction that uses light as a clean reagent.

讨论

4-iodoanisole溶液和bis (pinacolato) diboron乙腈是放置在一个石英试管和辐照4小时300 W高压汞灯(最大365海里)。根据1 h核磁共振分析原油产品,预期aryl-B(销)产品3中生成29%的收益率[5]。其他极性溶剂,如三uoroethanol和甲醇,几乎没有影响。在这两种情况下,使用水和丙酮作为co-solvents导致产量增加46%。各种各样的有机和无机添加测试后,发现有机基地,N, N, N0, N0-tetramethyldiaminomethane (TMDAM),可能会使收益率58%。其他基地,另一方面,产生差的结果。令人惊讶的是,更高的TMDAM导致产量下降。使用两个B2 (pin) 2等价物可以增加收益率72%。改变1的反应浓度进一步调整后导致了更大的收益。传统方法生成arylboron化合物包括反应arylmetallic中间体的三烃基硼酸盐,其次是transesterication或水解(1、3、5)。这些反应有很多缺点,包括有限的官能团容忍和严格的无水条件的必要性。 In recent decades, transition metal-catalyzed borylation techniques such as palladium, nickel, copper, and zinc have emerged as particularly useful methods for converting C–X bonds to C–B bonds. More recently, direct C–H borylation procedures using transition-metal catalysts have been devised [6]. To reduce costs and the amount of heavy metal residue in final products, many transition-metal-free techniques for C–B bond synthesis have been devised. Ito and coworkers demonstrated that silylborane can be used as the sole borylating reagent in an alkali alkoxidemediated borylation of aryl halides.