189952-21-4Relevant academic research and scientific papers
New enantiopure binaphthyl-cinchona thiosquaramides: synthesis and application for enantioselective organocatalysis
Nagy, Sándor,Dargó, Gyula,Kisszékelyi, Péter,Fehér, Zsuzsanna,Simon, András,Barabás, Júlia,H?ltzl, Tibor,Mátrav?lgyi, Béla,Kárpáti, Levente,Drahos, László,Huszthy, Péter,Kupai, József
, p. 5948 - 5959 (2019)
This work presents the first successful applications of cinchona-thiosquaramides in asymmetric reactions. Binaphthyl-cinchona squaramides and thiosquaramides were synthesised, and then used as organocatalysts to promote the catalytic enantioselective Mich
Chitosan-supported cinchona urea: Sustainable organocatalyst for asymmetric Michael reaction
Abdelkawy, Mahmoud A.,Aly, El-Saied A.,El-Badawi, Mahmoud A.,Itsuno, Shinichi
, (2020)
A novel chitosan-supported cinchona urea heterogeneous catalyst was developed for asymmetric reaction. The catalytic activity of the chitosan-supported organocatalyst was examined in the asymmetric Michael addition reaction to give chiral adducts in good
Synthesis and Applications of Cinchona Squaramide-Modified Poly(Glycidyl Methacrylate) Microspheres as Recyclable Polymer-Grafted Enantioselective Organocatalysts
Nagy, Sándor,Fehér, Zsuzsanna,Kárpáti, Levente,Bagi, Péter,Kisszékelyi, Péter,Koczka, Béla,Huszthy, Péter,Pukánszky, Béla,Kupai, József
, p. 13513 - 13522 (2020)
This work presents the immobilization of cinchona squaramide organocatalysts on poly(glycidyl methacrylate) solid supports. Preparation of the well-defined monodisperse polymer microspheres was facilitated by comprehensive parameter optimization. By explo
Mechanistic investigations of a bifunctional squaramide organocatalyst in asymmetric Michael reaction and observation of stereoselective retro-Michael reaction
Varga, Eszter,Mika, László Tamás,Csámpai, Antal,Holczbauer, Tamás,Kardos, Gy?rgy,Soós, Tibor
, p. 95079 - 95086 (2015)
The mechanism of the addition of acetylacetone to β-nitrostyrene catalyzed by a cinchona based squaramide catalyst was studied in detail under synthetically relevant conditions. The reaction was monitored by in situ IR and 1H-NMR spectroscopy and a reaction mechanism was proposed based on these kinetics experiments. It was found that the reaction shows nearly first order dependence on both substrates and catalyst. Our investigations also revealed that the catalyst was able to promote stereoselective retro-Michael reaction.
Chiral calcium catalysts with neutral coordinative ligands: Enantioselective 1,4-addition reactions of 1,3-dicarbonyl compounds to nitroalkenes
Tsubogo, Tetsu,Yamashita, Yasuhiro,Kobayashi, Shu
, p. 9117 - 9120 (2009)
Salt of the earth: The first chiral, coordinate alkaline earth metal catalysts have been developed. These catalysts effectively promote catalytic asymmetric additions of ss-dicarbonyl compounds to nitroalkenes in high yields with high enantioselectivities
A novel isosteviol-based bifunctional squaramide organocatalyst for enantioselective Michael addition of acetylacetone to nitroolefins
Ma, Zhiwei,Liu, Zhijing,Wang, Chuanchuan,Chen, Xiaopei,Tao, Jingchao,Lv, Quanjian
, p. 77 - 85 (2021/11/10)
Chiral amine-squaramide is a kind of effective hydrogen bond donor bifunctional catalyst to promote many asymmetric transformations. In this paper, novel chiral tertiary amine-squaramide derived from the natural product of the stevioside was developed and
Synthesis, characterization and catalytic performance in enantioselective reactions by mesoporous silica materials functionalized with chiral thiourea-amine ligand
G?k, Ya?ar,G?k, Halil Zeki
, p. 853 - 874 (2020/11/10)
Chiral heterogeneous catalysts have been synthesized by grafting of silyl derivatives of (1R, 2R)- or (1S, 2S)-1,2-diphenylethane-1,2-diamine on SBA-15 mesoporous support. The mesoporous material SBA-15 and so-prepared chiral heterogeneous catalysts were characterized by a combination of different techniques such as X-ray diffractometry (XRD), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), and Brunauer–Emmett–Teller (BET) surface area. Results showed that (1R, 2R)- and (1S, 2S)-1,2-diphenylethane-1,2-diamine were successively immobilized on SBA-15 mesoporous support. Chiral heterogeneous catalysts and their homogenous counterparts were tested in enantioselective transfer hydrogenation of aromatic ketones and enantioselective Michael addition of acetylacetone to β-nitroolefin derivatives. The catalysts demonstrated notably high catalytic conversions (up to 99%) with moderate enantiomeric excess (up to 30% ee) for the heterogeneous enantioselective transfer hydrogenation. The catalytic performances for enantioselective Michael reaction showed excellent activities (up to 99%) with poor enantioselectivities. Particularly, the chiral heterogeneous catalysts could be readily recycled for Michael reaction and reused in three consecutive catalytic experiments with no loss of catalytic efficacies.
Synthesis of cinchona squaramide polymers by Yamamoto coupling polymerization and their application in asymmetric Michael reaction
Chhanda, Sadia Afrin,Itsuno, Shinichi
, (2021/05/13)
Yamamoto coupling polymerization has been used for the synthesis of polymeric chiral organocatalysts. Cinchona squaramide derivatives with dibromophenyl moiety were polymerized under the Yamamoto coupling conditions to afford the corresponding chiral polymers in good yields. Using this technique, novel cinchona alkaloid polymers containing the squaramide moiety were designed and successfully synthesized. In addition to the homopolymerization of cinchona squaramide monomers with a dibromophenyl group, achiral comonomers such as dibromobenzene were copolymerized with the cinchona monomers to yield chiral copolymers. These chiral polymers were successfully utilized as polymeric catalysts in asymmetric Michael addition reactions. Good to excellent enantioselectivities were observed for different types of asymmetric Michael reactions. Using the chiral homopolymer catalyst P4, almost perfect diastereoselectivity (>100:1) with 99% ee was obtained for the reaction between methyl 2-oxocyclopentanecarboxylate 25 and trans-β-nitrostyrene 17. The polymer catalysts developed in this study have robust structures and can be reused several times without a loss in their catalytic activities.
Novel 1,2,3-triazole epicinchonas: Transitioning from organocatalysis to biological activities
Barrulas, Pedro,Carreiro, Elisabete P.,Veiros, Luis F.,Amorim, Ana C.,Gut, Giri,Rosenthal, Philip J.,López, óscar,Puerta, Adrián,Padrón, José M.,Fernández-Bola?os, José G.,Burke, Anthony J.
, p. 2954 - 2974 (2021/08/24)
A small family of novel modular monofunctional epicinchonidine-1,2,3-triazole compounds was prepared in very good overall yield (3 steps from cinchonidine, 49–87% yield) using simple Cu(I) catalyzed click-chemistry. The objective of this study was to acce
Asymmetric Michael addition reactions catalyzed by a novel upper-rim functionalized calix[4]squaramide organocatalyst
Yang, Ke,Ma, Zhiyan,Tong, Hong-Xiao,Sun, Xiao-Qiang,Hu, Xiao-Yu,Li, Zheng-Yi
supporting information, p. 3259 - 3262 (2020/03/19)
A novel upper-rim functionalized calix[4]squaramide organocatalyst bearing bis-squaramide and cyclohexanediamine scaffolds was designed and prepared to catalyse a serial of asymmetric Michael addition of 1,3-dicarbonyl compounds to α,β-unsaturated carbony
