A simple synthesis of series of new catalysts derived from chiral bifunctional ureas is described. The aza-Henry reaction of imines with nitromethane was promoted by sugar derived bifunctional organocatalysts to give optically active β-nitroamines. The aza-Henry reaction products were obtained in good yields (35-98%) and ee up to 99%.
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http://dx.doi.org/10.1016/j.carres.2014.11.019 | DOI Listing |
Org Process Res Dev
September 2024
School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, U.K.
Perylene diimides (PDI) have an extraordinary ability to activate both energy and electron transfer processes upon light excitation; however, their extremely low solubility has hindered their wide use as photocatalysts. Here, we show that the combination of solid-supported PDIs with continuous flow photochemistry offers a promising strategy for process intensification and a scalable platform for heterogeneous photocatalysis. The photocatalyst immobilized onto glass beads is highly efficient, easy to separate, and extremely reusable, with a broad synthetic application range.
View Article and Find Full Text PDFOrg Biomol Chem
September 2024
Department of Chemistry, Graduate School of Natural Science and Technology, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504, Japan.
We report a metal/light-free aerobic oxidative C-C bond formation using sp C-H bond activation of tetrahydroisoquinolines catalyzed by flavin and iodine. The dual catalytic system enabled the oxidative Mannich and aza-Henry reactions by the cross-dehydrogenative coupling between two sp C-H bonds. Furthermore, the flavin-iodine-coupled catalysis was applied to the synthesis of pyrrolo[2,1-]isoquinolines through the sequential oxidative 1,3-dipolar cycloaddition and dehydrogenative aromatization.
View Article and Find Full Text PDFChemistry
November 2024
State Key Laboratory of Petroleum Molecular & Process Engineering, Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N Zhongshan Road, Shanghai, 200062, China.
We report an H-bond donor controlled diastereoselective switchable intramolecular aza-Henry reaction of ketimines derived from α-ketoesters and 2-(2-nitroethyl)anilines, allowing facile access to chiral tetrahydroquinolines bearing an aza-quaternary carbon stereocenter, which are privileged scaffold for medicinal researches. While newly developed cinchona alkaloid derived phosphoramide-bearing quaternary ammonium salt C2 selectively give cis-adducts in up to 20 : 1 dr and 99 % ee, the corresponding urea-bearing analogue C8 preferentially give trans-adducts in up to 20 : 1 dr and 99 % ee.
View Article and Find Full Text PDFChem Soc Rev
July 2024
Centro de Innovación en Química Avanzada (ORFEO-CINQA), Universidad de Alicante, Apdo. 99, E-03080 Alicante, Spain.
The asymmetric catalytic synthesis of 1,2-diamines has received considerable interest, especially in the last ten years, due to their presence in biologically active compounds and their applications for the development of synthetic building blocks, chiral ligands and organocatalysts. Synthetic strategies based on C-N bond-forming reactions involve mainly (a) ring opening of aziridines and azabenzonorbornadienes, (b) hydroamination of allylic amines, (c) hydroamination of enamines and (d) diamination of olefins. In the case of C-C bond-forming reactions are included (a) the aza-Mannich reaction of imino esters, imino nitriles, azlactones, isocyano acetates, and isothiocyanates with imines, (b) the aza-Henry reaction of nitroalkanes with imines, (c) imine-imine coupling reactions, and (d) reductive coupling of enamines with imines, and (e) [3+2] cycloaddition with imines.
View Article and Find Full Text PDFFront Chem
May 2024
Laboratory of Fluorine and Nitrogen Chemistry and Advanced Materials, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China.
Amino acid-derived quaternary ammonium salts were successfully applied in the asymmetric aza-Henry reaction of nitromethane to -Boc trifluoromethyl ketimines. α-Trifluoromethyl β-nitroamines were synthesized in good to excellent yields with moderate to good enantioselectivities. This reaction is distinguished by its mild conditions, low catalyst loading (1 mol%), and catalytic base.
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