The ruthenium‐catalyzed redox isomerization of allylic alcohols was successfully coupled with the enantioselective enzymatic ketone reduction (mediated by KREDs) in a concurrent process in aqueous medium. The overall transformation, formally the asymmetric reduction of allylic alcohols, took place with excellent conversions and enantioselectivities, under mild reaction conditions, employing commercially
isolated O-coordinated Ru(II)-pyridine-N-oxide complex has been investigated to reveal the photodynamics. The Ru(IV)-oxocomplex with an uncoordinated pyridine moiety was alternatively prepared by reaction of the corresponding acetonitrile complex with 2,6-dichloropyridine-N-oxide (Cl(2)py-O) to identify the Ru(IV)-oxo species. The formation of Ru(IV)-oxocomplexes was concluded to proceed via intermolecular
activity in cyclohexene oxidation (TOF = 72 h(-1)) were detected. Partial retention of configuration (RC = 53%) in cis- and trans-1,2-dimethylcyclohexane oxidation, moderate 3 degrees/2 degrees selectivity (4.1) in adamantane oxidation, and the observation of a relatively high kinetic isotope effect for cyclohexane oxidation (KIE = 3.27) suggest partial metal-based oxidation, probably in tandem with free-radical
underwent structural transformation in the presence of H2O2 but regenerated to their initial state at the end of the reaction. In particular, the highly dispersed Nb oxoclusters can absorb a large amount of polar organic solvents and thus were swollen greatly, which exhibited “pseudo” liquid phase behavior, and enabled the substrate molecules to be highly accessible to the catalytic center of Nb oxocluster
我们在这里提出了一种新型的铌氧簇,它可以通过羧酸盐离子液体有效地稳定下来。这些功能化的IL在本工作中分别命名为[TBA] [LA],[TBA] [PA]和[TBA] [HPA],其中TBA代表四丁基铵,LA,PA和HPA分别指乳酸,丙酸酯,3 -羟基丙酸酯阴离子。已通过元素分析,NMR,IR,XRD,TGA和HRTEM对合成的Nb氧簇进行了表征。发现[TBA] [LA]稳定的Nb氧簇(Nb-OC @ [TBA] [LA])均匀分散,平均粒径为2-3 nm,并具有极高的催化活性,可选择性氧化各种硫醚。在催化剂负载量低至0.0033 mol%(1 ppm)时,Nb-OC @ [TBA] [LA]催化剂的周转数超过56000。与此同时,通过仅使用0.065mol%的催化剂(50ppm),该催化剂还显示出对烯烃和烯丙基醇的环氧化的高活性。的表征93 Nb NMR光谱表明,Nb氧簇在H 2 O 2存
Catalytic Phosphorus(V)-Mediated Nucleophilic Substitution Reactions: Development of a Catalytic Appel Reaction
作者:Ross M. Denton、Jie An、Beatrice Adeniran、Alexander J. Blake、William Lewis、Andrew M. Poulton
DOI:10.1021/jo201085r
日期:2011.8.19
from stoichiometric waste products into catalysts and a new concept for catalytic phosphorus-based activation and nucleophilicsubstitution of alcohols has been validated. The present study has focused on a full exploration of the scope and limitations of phosphine oxide catalyzed chlorination reactions as well as the development of the analogous bromination reactions. Further mechanistic studies, including