Photoenzymatic Hydrogenation of Heteroaromatic Olefins Using ‘Ene’‐Reductases with Photoredox Catalysts
作者:Yuji Nakano、Michael J. Black、Andrew J. Meichan、Braddock A. Sandoval、Megan M. Chung、Kyle F. Biegasiewicz、Tianyu Zhu、Todd K. Hyster
DOI:10.1002/anie.202003125
日期:2020.6.22
selective catalysts for the asymmetric reduction of activated alkenes. This function is, however, limited to enones, enoates, and nitroalkenes using the native hydride transfer mechanism. Here we demonstrate that EREDs can reduce vinyl pyridines when irradiated with visible light in the presence of a photoredoxcatalyst. Experimental evidence suggests the reaction proceeds via a radical mechanism where
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
Ligand coupling through σ-sulfurane — complete retention of configuration of 1-phenylethyl group in the reaction of 1-phenylethyl 2-pyridyl sulfoxide with grignard reagent1
作者:Shigeru Oae、Tsutomu Kawai、Naomichi Furukawa
DOI:10.1016/s0040-4039(01)91150-5
日期:1984.1
The reaction of benzyl or 1-phenylethyl 2-pyridyl sulfoxide with Grignard reagent proceeds via a σ-sulfurane as an intermediate to give the coupling product, 2-benzylpyridine or 2-(1-phenylethyl)pyridine in quantitative yield. Stereochemistry for this reaction is complete retention at the benzylic carbon atom.
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。
The reduction of acetophenone by hydrogentransfer from isopropranol is catalyzed by rhodium(I) complexes containing optically active 2-(2′-pyridyl)pyridines. Optical yields up to 15% have been obtained.