1440934-21-3Relevant academic research and scientific papers
Catalytic Asymmetric Addition of Diorganozinc Reagents to Pyrazole-4,5-Diones and Indoline-2,3-Diones
Wang, Rong-Hui,Li, Ya-Ling,He, Hong-Jiao,Xiao, You-Cai,Chen, Fen-Er
, p. 4302 - 4306 (2021/02/16)
The catalytic enantioselective diorganozinc additions to cyclic diketones including pyrazolin-4,5-diones and isatins have been developed. In the presence of morpholine-containing chiral amino alcohol ligand, the corresponding chiral cyclic tertiary alcohols were produced in good to excellent yields (up to 97 %) and enantioselectivities (up to 95 % ee). The notable feature of this protocol includes its mild reaction conditions, Lewis acid additives free and broad functional group tolerance.
The Importance of 1,5-Oxygen???Chalcogen Interactions in Enantioselective Isochalcogenourea Catalysis
Cockroft, Scott L.,Elmi, Alex,Frost, Aileen B.,Ling, Kenneth B.,McLaughlin, Calum,Morris, Rylie K.,Pascoe, Dominic J.,Slawin, Alexandra M. Z.,Smith, Andrew D.,Smith, Terry K.,Willoughby, Patrick H.,Woods, Andrew M.,Young, Claire M.,de la Houpliere, Alix
, p. 3705 - 3710 (2020/02/11)
The importance of 1,5-O???chalcogen (Ch) interactions in isochalcogenourea catalysis (Ch=O, S, Se) is investigated. Conformational analyses of N-acyl isochalcogenouronium species and comparison with kinetic data demonstrate the significance of 1,5-O???Ch interactions in enantioselective catalysis. Importantly, the selenium analogue demonstrates enhanced rate and selectivity profiles across a range of reaction processes including nitronate conjugate addition and formal [4+2] cycloadditions. A gram-scale synthesis of the most active selenium analogue was developed using a previously unreported seleno-Hugerschoff reaction, allowing the challenging kinetic resolutions of tertiary alcohols to be performed at 500 ppm catalyst loading. Density functional theory (DFT) and natural bond orbital (NBO) calculations support the role of orbital delocalization (occurring by intramolecular chalcogen bonding) in determining the conformation, equilibrium population, and reactivity of N-acylated intermediates.
Kinetic resolution of tertiary alcohols: Highly enantioselective access to 3-hydroxy-3-substituted oxindoles
Lu, Shenci,Poh, Si Bei,Siau, Woon-Yew,Zhao, Yu
supporting information, p. 1731 - 1734 (2013/04/10)
Enantioselective: The first highly enantioselective kinetic resolution of 3-hydroxy-3-substituted oxindoles has been developed through oxidative esterification catalyzed by a N-heterocyclic carbene (see picture). This method uses a simple procedure and provides 3-hydroxy-oxindoles with various substituents at the 3-position in excellent enantiopurity. S=selectivity. Copyright
Pentanidium-catalyzed enantioselective α-hydroxylation of oxindoles using molecular oxygen
Yang, Yuanyong,Moinodeen, Farhana,Chin, Willy,Ma, Ting,Jiang, Zhiyong,Tan, Choon-Hong
supporting information, p. 4762 - 4765 (2013/01/15)
Pentanidium-catalyzed α-hydroxylation of 3-substituted-2-oxindoles using molecular oxygen has been developed with good yields and enantioselectivities. This reaction does not require an additional reductant such as triethyl phosphite, which was typically added to reduce the peroxide intermediate. The reaction was demonstrated to consist of two-steps: an enantioselective formation of hydroperoxide oxindole and a kinetic resolution of the hydroperoxide oxindole via reduction with enolates generated from the oxindoles.
