2224-38-6Relevant academic research and scientific papers
α-Nitro-α,β-Unsaturated Ketones: An Electrophilic Acyl Transfer Reagent in Catalytic Asymmetric Friedel-Crafts and Michael Reactions
Parida, Chandrakanta,Maity, Rajendra,Chandra Sahoo, Subas,Chandra Pan, Subhas
supporting information, p. 6700 - 6704 (2019/09/07)
Herein, we introduce α-nitro-α,β-unsaturated ketones as efficient electrophilic acyl transfer reagents, and they were employed in Friedel-Crafts as well as in Michael reactions. The desired acyl transfer products of these reactions were obtained in high yields with high to excellent enantioselectivities with t-leucine-derived squaramide catalyst under mild reaction conditions. Few applications including a synthesis of the isoxazoline motif have been demonstrated.
Unprecedented Mechanism of an Organocatalytic Route to Conjugated Enynes with a Junction to Cyclic Nitronates
Streitferdt, Verena,Haindl, Michael H.,Hioe, Johnny,Morana, Fabio,Renzi, Polyssena,von Rekowski, Felicitas,Zimmermann, Alexander,Nardi, Martina,Zeitler, Kirsten,Gschwind, Ruth M.
supporting information, p. 328 - 337 (2018/11/23)
Conjugated enynes as well as cyclic nitronates are crucial building blocks for numerous natural products and pharmaceuticals. However, so far, no common and metal-free synthetic route to both conjugated enynes and cyclic nitronates has been reported. Herein, in situ NMR, labelling studies and theoretical calculations were combined to investigate the mechanism of the unusual triple bond formation towards conjugated enynes. Starting from nitroalkene dimers, first an isoxazolidine-2,5-diol derivative is formed as central intermediate. From this, enynes were generated by a combination of oxidation, dehydration, and retro 1,3-dipolar cycloaddition, whereas for nitronates a base induced intramolecular reorganization is proposed. While the product distribution could be controlled and high yields of nitronate were achieved, only medium to good yields for enynes were obtained due to polymerization losses. Nevertheless, we hope that these mechanistic investigations may provide a basis for further developments of organocatalytic or metal-free preparations of conjugated enynes and nitronates.
Levopimaric acid derived 1,2-diamines and their application in the copper-catalyzed asymmetric Henry reaction
Khlebnikova, Tatiana B.,Konev, Vasily N.,Pai, Zinaida P.
supporting information, p. 260 - 267 (2017/12/11)
Levopimaric acid, a readily available starting material, was used in efficient syntheses of new enantiopure diamines and Schiff bases with good yields. The synthetic procedure is based on the fumaropimaric acid monomethyl ester conversion into the optical
Synthesis of unsaturated silyl nitronates via the silylation of conjugated nitroalkenes
Khotyantseva, Elizaveta A.,Tabolin, Andrey A.,Novikov, Roman A.,Nelyubina, Yulia V.,Ioffe, Sema L.
supporting information, p. 3128 - 3131 (2018/07/13)
A new method for the synthesis of conjugated silyl nitronates from nitroalkenes is described. The procedure has wide substrate scope and is compatible with in situ generation of the substrates from 2-nitroalcohols or 2-chloro-nitroalkanes. A cascade transformation to give 3,4,5,6-tetrahydropyridine N-oxide derivatives was disclosed.
A new series of bipyridine based chiral organocatalysts for enantioselective Henry reaction
Ashokkumar, Veeramanoharan,Duraimurugan, Kumaraguru,Siva, Ayyanar
supporting information, p. 7148 - 7156 (2016/08/09)
A series of binaphthol based chiral organocatalysts were synthesized and applied as metal-free organocatalysts in the enantioselective Henry reaction. These organocatalysts enabled the Henry reaction with a lower concentration of catalysts at room tempera
Organocatalytic Enantioselective Transfer Hydrogenation of β-Amino Nitroolefins
Ferraro, Antonino,Bernardi, Luca,Fochi, Mariafrancesca
supporting information, p. 1561 - 1565 (2016/10/13)
The asymmetric organocatalytic transfer hydrogenation of β-acylamino and β-tert-butyloxycarbonylamino nitroolefins has been successfully realised in excellent enantioselectivities and yields (up to >99% ee, 97% yield) with a simple thiourea catalyst and a Hantzsch ester as hydrogen source, giving a direct access to enantiomerically pure β-amino nitroalkanes. (Figure presented.).
Asymmetric Henry reaction catalyzed by Cu(II)-based chiral amino alcohol complexes with C2-symmetry
Lu, Gonghao,Zheng, Fei,Wang, Lei,Guo, Yuxin,Li, Xue,Cao, Xianjun,Wang, Cuiping,Chi, Haijun,Dong, Yan,Zhang, Zhiqiang
, p. 732 - 739 (2016/07/29)
A series of chiral amino alcohol ligands was prepared using commercial amino alcohols and phthalaldehydes. These ligands were used as catalysts in asymmetric Henry reactions in the presence of Cu(II) ions giving good yields (up to 97%) and enantiomeric excesses (ee, up to 98%). The DFT calculations showed the effect of the trans/cis configurations of the Cu-complexes on the origin of enantioselectivity. The easy catalyst preparation, mild reaction conditions, high yields and excellent enantioselectivities make these catalysts suitable for widespread use.
Cu (II)-catalyzed asymmetric Henry reaction with a novel C1-symmetric aminopinane-derived ligand
Filippova, Liudmila,Stenstrom, Yngve,Hansen, Trond Vidar
, p. 6224 - 6236 (2015/05/13)
A novel C1-symmetric dinitrogen ligand was synthesized in high yield from commercially available (1R,2R,3R,5S)-(-)-isopinocampheylamine and 1-methyl-2-imidazolecarboxaldehyde. In combination with Cu(OAc)2·H2O, this new ligand promote the reaction between nitromethane and aliphatic aldehydes with high yields (up to 97%) and moderate enantioselectivities (up to 67% ee). The reactions with benzaldehyde required prolonged reaction time that resulted in diminished yields, but accompanied with ee-values in the 55%-76% range.
Kinetic resolution of racemic amino alcohols through intermolecular acetalization catalyzed by a chiral Bronsted acid
Yamanaka, Takuto,Kondoh, Azusa,Terada, Masahiro
supporting information, p. 1048 - 1051 (2015/02/19)
The kinetic resolution of racemic secondary alcohols is a fundamental method for obtaining enantiomerically enriched alcohols. Compared to esterification, which is a well-established method for this purpose, kinetic resolution through enantioselective intermolecular acetalization has not been reported to date despite the fact that the formation of acetals is widely adopted to protect hydroxy groups. By taking advantage of the thermodynamics of acetalization by the addition of alcohols to enol ethers, a highly efficient kinetic resolution of racemic amino alcohols was achieved for the first time and in a practical manner using a chiral phosphoric acid catalyst.
Enantio- & chemo-selective preparation of enantiomerically enriched aliphatic nitro alcohols using Candida parapsilosis ATCC 7330
Venkataraman, Sowmyalakshmi,Chadha, Anju
, p. 73807 - 73813 (2015/09/15)
Enantiomerically pure β- and γ-nitro alcohols were prepared from their respective nitro ketones by asymmetric reduction mediated by the biocatalyst, Candida parapsilosis ATCC 7330 under optimized reaction conditions (ee up to >99%; yields up to 76%). This
