Catalytic Transfer Hydrogenation Using Biomass as Hydrogen Source
作者:Srimanta Manna、Andrey P. Antonchick
DOI:10.1002/cssc.201801770
日期:2019.7.5
entities in a fundamentally important process, such as hydrogenation. Various carbohydrates, starch, and lignin were used for stereoselective hydrogenation. Employing a transition metal catalyst and a novel catalytic system, the reduction of alkynes, alkenes, and carbonyl groups with high yields was demonstrated. The regioselective hydrogenation to access different stereoisomers was established by simple
Take two: By employing two equivalents of an aldehyde in an asymmetricorganocatalyticdominoreaction, the nucleophilic enamine intermediate is also converted into the corresponding iminium species through oxidation with o‐iodoxybenzoic acid. Thus, polyfunctionalized cyclohexene derivatives are formed from two simple starting materials in good yields and stereoselectivities (see scheme; Bn=benzyl
A highly regio- and stereoselective [3 + 2] cycloadditionreaction for constructing novel 3,3′-cyclopentenyldispirooxindoles incorporating two adjacent quaternary spirostereocenters is reported. Under the mild conditions, the asymmetric annulation of isatin-derived MBH carbonates with 3-methyleneoxindoles involving a chiral tertiary amine catalyst provides the corresponding dispirooxindole frameworks
Highly Efficient Enantioselective Construction of Bispirooxindoles Containing Three Stereocenters through an Organocatalytic Cascade Michael-Cyclization Reaction
作者:Hao Wu、Li-Li Zhang、Zhi-Qing Tian、Yao-Dong Huang、Yong-Mei Wang
DOI:10.1002/chem.201203221
日期:2013.1.28
Bispirooxindole derivatives containing three stereocenters, including two spiro quaternary centers, were synthesized in a high‐yielding, atypically rapid, and stereocontrolled cascade Michael–cyclization reaction between methyleneindolinones and isothiocyanato oxindoles catalyzed by a bi‐ or multifunctional organocatalyst. Mild conditions were used to construct bispirooxindoles with excellent enantio‐
Brønsted Base and Lewis Acid Cooperatively Catalyzed Asymmetric <i>exo</i>′-Selective [3 + 2] Cycloaddition of Trifluoromethylated Azomethine Ylides and Methyleneindolinones
作者:Yang Yi、Yuan-Zhao Hua、Hui-Jie Lu、Lan-Tao Liu、Min-Can Wang
DOI:10.1021/acs.orglett.0c00283
日期:2020.4.3
3-dipolar cycloaddition is reported through chiral dinuclear zinc catalysts. An asymmetric exo′-selective [3 + 2] cycloaddition of CF3-containing N-unprotected isatin-derived azomethineylides is realized. In the presence of 10 mol % of catalyst, azomethineylides react efficiently with methyleneindolinones, giving a series of trifluoromethyl-substituted 2,3-pyrrolidinyl dispirooxindoles with highly enantio-