State Key Laboratory for Oxo Synthesis and Selective Oxidation , Center for Excellence in Molecular Synthesis, Suzhou Research Institute, Lanzhou Institute of Chemical Physics, University of Chinese Academy of Sciences, Chinese Academy of Sciences , Lanzhou 73000 , China.
School of Materials Science & Engineering, PCFM Lab , Sun Yat-sen University , Guangzhou 510275 , China.
J Am Chem Soc. 2019 Apr 3;141(13):5334-5342. doi: 10.1021/jacs.8b13756. Epub 2019 Mar 20.
Optically active organoboronic acids and their derivatives are an important family of target compounds in organic chemistry, catalysis, and medicinal chemistry. Yet there are rare asymmetric catalytic examples reported for the synthesis of these compounds via atom and step economic ways. Herein, we report a chelate-directed iridium-catalyzed asymmetric C(sp)-H borylation of aromatic C-H bonds directed by free amine groups. The success of these transformations relies on a novel family of chiral bidentate boryl ligands (L). They can be synthesized straightforwardly in three steps starting from readily available ( S, S)-1,2-diphenyl-1,2-ethanediamie (( S, S)-DPEN). The Ir-catalyzed C(sp)-H borylation comprises two parts. The first part is desymmetrization of prochiral diarylmethylamines. In the presence of L3/Ir, a vast array of corresponding borylated products were obtained with high regioselectivity and good to excellent enantioselectivities (26 examples, up to 96% ee). The second part, kinetic resolution of racemic diarylmethylamines, was also conducted. Good selectivity values (up to 68%, 11 examples) were obtained when L8 was used. We also demonstrated the synthetic utility of the current method on gram-scale reaction for several transformations. The C-B bonds of borylated products could be converted to a variety of functionalities including C-O, C-C, C-C, C-Br, and C-P bonds. Finally, we performed DFT calculations of desymmetrization to understand its reaction pathways.
手性有机硼化合物及其衍生物是有机化学、催化和药物化学中重要的目标化合物家族。然而，通过原子经济性和步骤经济性的方法来合成这些化合物的不对称催化例子很少。在此，我们报道了一种螯合导向的铱催化不对称 C(sp 3 )-H 硼化反应，通过自由胺基导向芳基 C-H 键。这些转化的成功依赖于一类新型的手性双齿硼基配体 (L)。它们可以从易得的 (S, S)-1,2-二苯基-1,2-乙二胺 ((S, S)-DPEN) 出发，通过三步直接合成。铱催化的 C(sp 3 )-H 硼化反应由两部分组成。第一部分是前手性二芳基甲胺的去对称化。在 L3/Ir 的存在下，大量相应的硼化产物以高区域选择性和良好到优秀的对映选择性（26 个例子，最高 96%ee）得到。第二部分，外消旋二芳基甲胺的动力学拆分，也进行了。当使用 L8 时，得到了良好的选择性值（最高 68%，11 个例子）。我们还在几个转化的克级反应中展示了该方法的合成实用性。硼化产物的 C-B 键可以转化为多种官能团，包括 C-O、C-C、C-C、C-Br 和 C-P 键。最后，我们进行了去对称化的 DFT 计算，以了解其反应途径。
