Organocatalytic Enantioselective 1,3-Dipolar Cycloadditions between Seyferth–Gilbert Reagent and Isatylidene Malononitriles: Synthesis of Chiral Spiro-phosphonylpyrazoline-oxindoles
作者:Taiping Du、Fei Du、Yanqiang Ning、Yungui Peng
DOI:10.1021/acs.orglett.5b00311
日期:2015.3.6
A new method has been developed for the catalytic enantioselective 1,3-dipolar cycloaddition of the Seyferth–Gilbert reagent (SGR) to isatylidene malononitriles using a cinchonaalkaloidderivative as a catalyst. This method allowed for the synthesis of a series of chiral spiro-phosphonylpyrazoline-oxindoles in good yields with excellent enantioselectivities. The synthetic utility of this method was
Direct Catalytic Asymmetric Synthesis of Trifluoromethylated γ-Amino Esters/Lactones via Umpolung Strategy
作者:Bin Hu、Li Deng
DOI:10.1021/acs.joc.8b02893
日期:2019.1.18
Enabled by the discovery of new cinchonium salts and coadditives, a direct and efficient asymmetric access to trifluoromethylated γ-amino esters/lactones has been realized through the enantioselective and diastereoselective umpolung reaction of trifluoromethyl imines with acrylates or α,β-unsaturated lactones as carbon electrophiles. At 0.5-5.0 mol % catalyst loadings, the newly developed catalytic
Enantioselective Sulfonimidamide Acylation via a Cinchona Alkaloid-Catalyzed Desymmetrization: Scope, Data Science, and Mechanistic Investigation
作者:Brittany C. Haas、Ngiap-Kie Lim、Janis Jermaks、Eden Gaster、Melody C. Guo、Thomas C. Malig、Jacob Werth、Haiming Zhang、F. Dean Toste、Francis Gosselin、Scott J. Miller、Matthew S. Sigman
DOI:10.1021/jacs.4c00374
日期:2024.3.27
cinchona-phosphinate catalyst. The desired products are formed in excellent yield and enantioselectivity with no observed bis-acylation. A data-science-driven approach to substrate scope evaluation was coupled to high throughput experimentation (HTE) to facilitate statistical modeling in order to inform mechanistic studies. Reaction kinetics, catalyst structural studies, and density functional theory
Grimaux; Arnaud, Bulletin de la Societe Chimique de France, 1892, vol. <3> 7, p. 306
作者:Grimaux、Arnaud
DOI:——
日期:——
Development of C-6′-modified quinine-derived phase-transfer catalysts and their application in the enantioselective α-hydroxylation of β-dicarbonyl compounds
We have developed C-6'-modified quinine quaternary ammonium salts as phase transfer catalysts for alpha-hydroxylation of beta-dicarbonyl compounds. The quinine quaternary ammonium salts, which was modified at C-6' and the N atom, had good activity for alpha-hydroxylation of B-dicarbonyl compounds. By using 5 mol % of 6-hydroxyl-N-(4'-fluoro-2'-trifluoromethyl)quinine quaternary ammonium salt as the organocatalyst, cumene hydroperoxide as the oxidant, toluene as the solvent, and 50% K2HPO4 as the aqueous alkali at room, temperature, the yield and enantioselectivity of the alpha-hydroxylation of beta-keto esters were 95% and 88%, respectively. This catalytic system was also applicable for beta-keto amides (92% yield and 76% ee). (C) 2016 Elsevier Ltd. All rights reserved.