Dynamic Kinetic Resolution of Alcohols by Enantioselective Silylation Enabled by Two Orthogonal Transition‐Metal Catalysts
作者:Jan Seliger、Martin Oestreich
DOI:10.1002/anie.202010484
日期:2021.1.4
A nonenzymatic dynamic kinetic resolution of acyclic and cyclic benzylic alcohols is reported. The approach merges rapid transition‐metal‐catalyzedalcoholracemization and enantioselective Cu‐H‐catalyzed dehydrogenative Si‐O coupling of alcohols and hydrosilanes. The catalytic processes are orthogonal, and the racemization catalyst does not promote any background reactions such as the racemization
Stereoselective Coupling of Prochiral Radicals with a Chiral <i>C</i><sub>2</sub>-Symmetric Nitroxide
作者:Rebecca Braslau、Neeta Naik、Hendrik Zipse
DOI:10.1021/ja000520u
日期:2000.9.1
The coupling reaction between a chiral C2-symmetric nitroxide, trans-2,5-dimethyl-2,5-diphenylpyrrolidin-1-oxyl (DPPO; 1), and a series of stabilized secondary prochiral radicals was studied to determine the factors that affect stereoselectivity. Both steric and electronic perturbations on the selectivity by the substituents of the prochiral radical were observed. The effects of temperature, solvent
Catalytic hydrogenation of carbonyl and nitro compounds using an [<i>N</i>,<i>O</i>]-chelate half-sandwich ruthenium catalyst
作者:Zi-Jian Yao、Jing-Wei Zhu、Nan Lin、Xin-Chao Qiao、Wei Deng
DOI:10.1039/c8dt02677g
日期:——
A series of N,O-chelate half-sandwich ruthenium complexes for both carbonyl and nitro compound hydrogenation have been synthesized based on β-ketoamino ligands. All complexes exhibited high activity for the catalytic hydrogenation of a series of ketones and nitroarenes with molecular H2 as the reducing reagent in aqueous medium. Consequently, the catalytic system showed the catalytic TON values of
Metal Triflate-Catalyzed Cationic Benzylation and Allylation of 1,3-Dicarbonyl Compounds
作者:Masahiro Noji、Yosuke Konno、Keitaro Ishii
DOI:10.1021/jo0705216
日期:2007.7.1
The rare earth metal and hafnium triflate-catalyzed secondary benzylation and allylation of 1,3-diketones, ketoesters, and ketoamides are described. The procedure was carried out under non-anhydrous conditions. Various 1-phenylethyl cations were generated from substituted 1-phenylethanols using 0.5 mol % of the metal triflates in CH3NO2. The cations reacted with 1,3-diketones and ketoesters to give
描述了稀土金属和三氟甲磺酸ha催化的1,3-二酮,酮酸酯和酮酰胺的二次苄基化和烯丙基化。该程序在无水条件下进行。在CH 3 NO 2中使用0.5摩尔%的金属三氟甲磺酸酯,由取代的1-苯基乙醇生成各种1-苯基乙基阳离子。。阳离子与1,3-二酮和酮酸酯反应生成苄基化产物,收率很高。根据GC分析,可根据三氟甲磺酸的路易斯酸度和反应温度通过选择催化剂轻松优化反应条件。叔烷基化的二酮和相应的酮酸酯也被苄基化,以57-84%的收率得到具有季碳原子的产物。与二酮和酮酯反应中使用的那些相比,酮酰胺反应需要更强的路易斯酸。在Hf(OTf)4的存在下,研究了在芳环上具有各种取代基的苄醇与作为二酮的二苯甲酰甲烷(2b)的反应。富电子苄醇与2b反应以86-96%的产率收率,缺电子醇则以79-65%的收率得到所需的产物。尽管具有强的吸电子基团,但是1-(4-硝基苯基)乙醇的反应以61%的收率得到了相应的产物。也可以