32338-47-9Relevant academic research and scientific papers
Photocontrolled Cobalt Catalysis for Selective Hydroboration of α,β-Unsaturated Ketones
Beltran, Frédéric,Bergamaschi, Enrico,Funes-Ardoiz, Ignacio,Teskey, Christopher J.
supporting information, p. 21176 - 21182 (2020/09/17)
Selectivity between 1,2 and 1,4 addition of a nucleophile to an α,β-unsaturated carbonyl compound has classically been modified by the addition of stoichiometric additives to the substrate or reagent to increase their “hard” or “soft” character. Here, we demonstrate a conceptually distinct approach that instead relies on controlling the coordination sphere of a catalyst with visible light. In this way, we bias the reaction down two divergent pathways, giving contrasting products in the catalytic hydroboration of α,β-unsaturated ketones. This includes direct access to previously elusive cyclic enolborates, via 1,4-selective hydroboration, providing a straightforward and stereoselective route to rare syn-aldol products in one-pot. DFT calculations and mechanistic experiments confirm two different mechanisms are operative, underpinning this unusual photocontrolled selectivity switch.
Reusable shuttles for exchangeable functional cargos: Reversibly assembled, magnetically powered organocatalysts for asymmetric aldol reactions
Mendoza, Carolina,de la Croix, Augustin,Riente, Paola,Llorens, Lluís,de Mendoza, Javier,Pericàs, Miquel A.
supporting information, (2019/09/17)
A supramolecular approach has been followed to support adamantyl substituted proline organocatalysts onto the surface of magnetite nanoparticles decorated with a β-cyclodextrin motif. The resulting magnetic nanoparticles (ca. ～10 nm diameter) were used as modular, magnetically recyclable catalysts in the asymmetric aldol reaction of aromatic aldehydes with cyclic ketones in water. The catalytic assemblies can be easily dismantled in organic media, and the recovered nanoparticles (magnetically powered chemical shuttles) re-complexed with another suitably substituted catalytic unit (replaceable functional cargo).
Ion-Tagged Prolinamide Organocatalysts for the Direct Aldol Reaction On-Water
Eyckens, Daniel J.,Brozinski, Hannah L.,Delaney, Joshua P.,Servinis, Linden,Naghashian, Sahar,Henderson, Luke C.
, p. 212 - 219 (2016/02/23)
A concise synthesis of two imidazolium ion-tagged prolinamide organocatalysts 3 and 4, varying in anionic component (CF3COO- and PF6 -, respectively) is presented. The latter could be classified as an ionic liqu
Synthesis of sulphur-modified bifunctional hydrotalcites and study of their surface characteristics by inverse gas chromatography
Ren, Xiaoqian,Hu, Xi,Zhang, Feng,Wang, Junge,Liang, Jinhua,Wu, Wenliang,Jiang, Min,Wang, Jun
, p. 4813 - 4820 (2015/10/05)
In this study, various sulphur-modified hydrotalcite catalysts were prepared, and the influence of calcination temperature on their acid-base properties was investigated. Structural characterization of the catalysts was studied using X-ray powder diffraction, scanning electron microscopy, N2 physisorption, elemental analysis and Fourier transform infrared spectroscopy. The structural characterization indicated that the layer structure of all catalysts was retained but the specific surface areas were enlarged. Inverse gas chromatography was carried out to quantitatively determine the catalysts' acid-base properties by calculating the thermodynamic parameters, including dispersive surface free energy, adsorption free energy, adsorption enthalpy, and acid-base interaction constants. The results showed that the strength and content of acidic and alkaline sites were enhanced with increasing calcination temperature. Moreover, several typical aldol condensation reactions were selected to study the catalytic activity of the developed catalysts. The results showed that the sulphur-modified hydrotalcite catalysts possess high activity and good regenerability for typical aldol condensation reactions.
Chiral Br?nsted Acid as a True Catalyst: Asymmetric Mukaiyama Aldol and Hosomi-Sakurai Allylation Reactions
Sai, Masahiro,Yamamoto, Hisashi
supporting information, p. 7091 - 7094 (2015/06/25)
Highly diastereo- and enantioselective Mukaiyama aldol reaction catalyzed by a new chiral Br?nsted acid, N-(perfluorooctanesulfonyl)thiophosphoramide, is described. The perfluorooctyl substituent on the sulfonyl group of the catalyst plays an essential role in the stereoselection. The catalyst also allows the asymmetric Hosomi-Sakurai allylation, which has been considerably challenging due to the low reactivity of allylsilanes. 29Si and 31P NMR monitoring reveals the characteristic feature of the thiophosphoramide catalyst, acting as a strong Br?nsted acid even in the presence of excess silyl nucleophiles, which cannot be found in other related phosphoric acid analogues.
Highly Enantio- and Diastereoselective l -Proline Derived Acetylglucose Amide Catalyzed Aldol Reaction of Ketones to Aldehydes under Solvent-Free Conditions
Han, Xiaoyu,Wang, Yongjiang,Gai, Xikun,Zeng, Xiaofei
supporting information, p. 2858 - 2862 (2015/12/18)
A novel organocatalyst was developed from d-glucosamine and l-proline, which was shown to catalyze the direct aldol reaction of ketones with aldehydes in a highly diastereoselective and enantioselective manner under solvent-free conditions. The presence o
Enantiopure azetidine-2-carboxamides as organocatalysts for direct asymmetric aldol reactions in aqueous and organic media
Song, Xixi,Liu, Ai-Xiang,Liu, Shan-Shan,Gao, Wen-Chao,Wang, Min-Can,Chang, Junbiao
, p. 1464 - 1470 (2014/02/14)
A family of enantiopure azetidine-2-caboxamides was asymmetrically synthesized, and was examined as organocatalyst in direct aldol reactions. A well chosen chiral azetidine-2-caboxamide was found to smoothly catalyze the direct aldol reaction of various benzaldehydes with acetone in brine, and β-hydroxy ketones were produced with enantiomeric excess up to 96%. The reaction of benzaldehydes with cyclic ketones also led to the formation of anti-products in diastereomeric ratio up to 99:1 and enantiomeric excess up to 99%.
Copper-catalyzed 1,4-addition reaction of Grignard reagent to enones using microflow system
Katayama, Haruo,Matsubara, Seijiro
, p. 471 - 472 (2013/06/05)
The copper-catalyzed conjugate addition of a Grignard reagent to an β-unsaturated ketone was performed in a microflow system. In the reaction using the microflow system, a chemoselective 1,4-addition reaction to an enone in the presence of a saturated ketone group proceeded successfully.
Synergistic effects within a C2-symmetric organocatalyst: The potential formation of a chiral catalytic pocket
Delaney, Joshua P.,Brozinski, Hannah L.,Henderson, Luke C.
, p. 2951 - 2960 (2013/07/26)
This study describes the synthesis of five novel C2-symmetric organocatalysts that facilitate the on-water asymmetric aldol reaction at low catalyst loading (1 mol%) without the use of additives. Each catalyst is composed of two diprolinamide units joined by a symmetric alkyl bridging group allowing for systematic modulation of catalytic site proximity. Typically, catalysts in this manuscript which bear the catalytic units in close proximity gave the best reaction outcomes in terms of conversion (up to >99%), diastereomeric ratio (4/96, syn/anti) and enantiomeric excess (up to 97%). This effect has been attributed to the assembly of a chiral pocket, facilitated by hydrogen bonding at the oil-in-water interface. The Royal Society of Chemistry 2013.
A magnesium-based multifunctional metal-organic framework: Synthesis, thermally induced structural variation, selective gas adsorption, photoluminescence and heterogeneous catalytic study
Saha, Debraj,Maity, Tanmoy,Das, Soma,Koner, Subratanath
, p. 13912 - 13922 (2013/09/24)
Three magnesium based carboxylate framework systems were prepared through a temperature-dependent synthesis. The compounds were synthesized by a hydrothermal method and characterized by single crystal X-ray diffraction analysis. A stepwise increase in the
