Highly enantioselective pyridine-directed rhodium-catalyzed asymmetric hydrogenation of challenging 1,1-diarylalkenes is achieved by using [Rh(NBD)DuanPhos]BF4 as a precatalyst. Various types of 2-pyridine substituted 1,1-diarylalkenes could be hydrogenated with good to excellent enantioselectivities, which provide an efficient route to the synthesis of pharmaceutically and biologically active compounds
phosphite mediated stereoretentive C–H alkylation of N-alkylpyridinium salts derived from chiral primary amines was achieved. The reaction proceeds through the activation of the N-alkylpyridinium salt substrate with a nucleophilic phosphite catalyst, followed by a base mediated [1,2] aza-Wittig rearrangement and subsequent catalyst dissociation for an overall N to C-2 alkyl migration. The scope and
实现了由手性伯胺衍生的N-烷基吡啶鎓盐的亚磷酸酯介导的立体保留 C-H 烷基化。该反应通过亲核亚磷酸酯催化剂活化N-烷基吡啶鎓盐底物,然后进行碱介导的 [1,2]氮杂-维蒂希重排以及随后的催化剂解离以实现 N 到 C-2 烷基的整体迁移。研究了立体保留的范围和程度,并进行了实验和理论研究以支持前所未有的氮杂-维蒂希重排-重芳化序列。根据我们对立体保留过程的理解,还建立了从外消旋起始材料和手性亚磷酸酯催化剂开始的催化对映选择性版本。该方法可以有效地获取吡啶系统中的三级和四级立体中心,这些中心在药物、生物活性天然产物、手性配体和催化剂中普遍存在。
Enantioselective C2–H Alkylation of Pyridines with 1,3-Dienes via Ni–Al Bimetallic Catalysis
作者:Jiang-Fei Li、Deng Pan、Hao-Rui Wang、Tao Zhang、Yi Li、Genping Huang、Mengchun Ye
DOI:10.1021/jacs.2c09306
日期:2022.10.19
A chiral phosphine oxide-ligated Ni–Al bimetallic catalyst was used to realize an enantioselective C2–H alkylation of pyridines without the need of a C2-block. A wide range of pyridines, including unsubstituted pyridine, C3, C4, and C2-substituted pyridines, and even complex pyridine-containing bioactive molecules are well compatible with the reaction, providing up to 81% yield and up to 97% ee.