氯磺酰化的聚苯乙烯(一种商品树脂)与对映体纯的1,2-二胺反应,可一步得到涉及单磺酰化的1,2-二氨基部分的高负载催化树脂。这些功能性聚合物形成稳定的对氯苯甲基氯化钌[RuCl(对苯甲基)]络合物,可在以下条件下有效地催化甲酸芳基三乙胺催化(低至S / C = 150)烷基芳基酮的不对称转移加氢(ATH)。基本上无溶剂(低至0.25 mL mmol -1)的反应条件。在这些树脂中,固定化形式的TsDPEN是用于ATH的最实用的催化剂:在催化剂用量低的情况下使用,可实现一致的高对映选择性,并且该树脂几乎可以无限循环使用。
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
Cells of the fungus, Geotrichum candidum, were immobilized on a water-absorbing polymer and used for stereoselective oxidation and reduction in an organic solvent using cyclohexanone, cyclopentanol or alkan-2-ols as additive. Enantiomerically pure (R)-1-arylethanols were obtained by the stereoselective oxidation of racemic 1-arylethanols, whereas enantiomerically pure (S)-1-arylethanols were obtained by the reduction of the corresponding ketones, in contrast to reduction in water by the free cells in which (R)- or (S)-1-arylethanols were produced in low ee.The reaction mechanism was investigated by measuring the partition of the substrates and products between the organic phase and aqueous phase in the polymer around which the cells were immobilized. Deuterated compounds were used to determine the role of the additives.
Iridium and Rhodium Complexes Containing Enantiopure Primary Amine-Tethered <i>N</i>-Heterocyclic Carbenes: Synthesis, Characterization, Reactivity, and Catalytic Asymmetric Hydrogenation of Ketones
作者:Kai Y. Wan、Florian Roelfes、Alan J. Lough、F. Ekkehardt Hahn、Robert H. Morris
DOI:10.1021/acs.organomet.7b00915
日期:2018.2.12
a bimetallic iridium compound with (S,S)-11 as the bridging ligand. This compound contains interesting NH···Cl and NH···Ir noncovalent intramolecular interactions. Salt (S,S)-12·HPF6 reacts with silver oxide to yield [Ag2((S,S)-12)2](PF6)2 (20). Reagent 20 serves as an efficient transmetalation reagent to deliver to each rhodium in [RhCl(cod)]2 1 equiv of (S,S)-12 as a bidentate ligand to give [Rh(cod)((S
Copper-Catalyzed Asymmetric Hydrogenation of Aryl and Heteroaryl Ketones
作者:Scott W. Krabbe、Mark A. Hatcher、Roy K. Bowman、Mark B. Mitchell、Michael S. McClure、Jeffrey S. Johnson
DOI:10.1021/ol4021223
日期:2013.9.6
High throughput screening enabled the development of a Cu-based catalyst system for the asymmetric hydrogenation of prochiral aryl and heteroarylketones that operates at H2 pressures as low as 5 bar. A ligand combination of (R,S)-N-Me-3,5-xylyl-BoPhoz and tris(3,5-xylyl)phosphine provided benzylic alcohols in good yields and enantioselectivities. The electronic and steric characteristics of the ancillary
Transfer hydrogenation reactions catalyzed by chiral half-sandwich Ruthenium complexes derived from Proline
作者:ARUN KUMAR PANDIA KUMAR、ASHOKA G SAMUELSON
DOI:10.1007/s12039-016-1151-8
日期:2016.9
Chiral ruthenium half-sandwich complexes were prepared using a chelating diamine made from proline with a phenyl, ethyl, or benzyl group, instead of hydrogen on one of the coordinating arms. Three of these complexes were obtained as single diastereoisomers and their configuration identified by X-ray crystallography. The complexes are recyclable catalysts for the reduction of ketones to chiral alcohols