891482-53-4Relevant academic research and scientific papers
Effective and recyclable dendritic ligands for the enantioselective epoxidation of enones
Liu, Xinyuan,Li, Yawen,Wang, Guangyin,Chai, Zhuo,Wu, Yongyong,Zhao, Gang
, p. 750 - 755 (2006)
An operationally simple and mild protocol for the catalytic enantioselective epoxidation of enones has been established using a series of chiral pyrrolidinylmethanol-based dendritic catalysts and tert-butyl hydroperoxide (TBHP) as an oxidant. The epoxides
Synthesis of xylal- and arabinal-based crown ethers and their application as asymmetric phase transfer catalysts
Nemcsok, Tamás,Rapi, Zsolt,Bagi, Péter,Keglevich, Gy?rgy,Bakó, Péter
, p. 107 - 119 (2019/11/16)
New xylal- and arabinal-based monoaza-15-crown-5 ethers were synthesized starting from l- and d-xylose, and l- and d-arabinose, respectively. These monosaccharide-based chiral macrocycles were tested as phase transfer catalysts in a few asymmetric reactions. The xylal-based crown compounds proved to be efficient catalysts in a few liquid-liquid phase reactions. The epoxidation of trans-chalcone and the Darzens condensation of α-chloroacetophenone with benzaldehyde took place with complete diastereoselectivity and up to 77% ee and 58% ee, respectively. It was found that the substituents in the aromatic ring of the chalcone and the α-chloroacetophenone had an influence on the enantioselectivity. The highest ee values were obtained in the epoxidation of 4-chlorochalcone (81% ee) and in the reaction of a 2-naphthyl analogue (96% ee), while in the Darzens condensation of 4-phenyl-α-chloroacetophenone with benzaldehyde, a maximum ee of 91% was detected. The configuration of the monosaccharide unit in the crown ring influenced the absolute configuration of the epoxyketones synthesized.
Kinetic resolution of 2,3-epoxy 3-aryl ketones via catalytic asymmetric ring-opening with pyrazole derivatives
Huang, Tianyu,Lin, Lili,Hu, Xiaolei,Zheng, Jianfeng,Liu, Xiaohua,Feng, Xiaoming
supporting information, p. 11374 - 11377 (2015/08/18)
A highly efficient catalytic kinetic resolution of 2,3-epoxy 3-aryl ketones via asymmetric ring-opening with pyrazole derivatives has been achieved by using a chiral N,N′-dioxide-Sc(III) complex as the catalyst. A wide variety of substrates were readily scoped, and the selectivity factors obtained were excellent (up to >300).
Asymmetric C-C bond formation via Darzens condensation and Michael addition using monosaccharide-based chiral crown ethers
Bakó, Péter,Rapi, Zsolt,Keglevich, Gy?rgy,Szabó, Tamás,Sóti, Péter L.,Vígh, Tamás,Grn, Alajos,Holczbauer, Tamás
experimental part, p. 1473 - 1476 (2011/06/10)
Liquid-liquid phase asymmetric Darzens condensations were promoted by d-glucose- and d-mannose-based crown ethers. The corresponding aromatic and heteroaromatic α,β-epoxyketones were obtained with moderate to high enantioselectivities (up to 96%) as well
