A copper-catalyzed asymmetric radical oxytrifluoromethylation of alkenyl oxime and Togni's reagent has been successfully developed, thereby providing straightforward access to CF -containing isoxazolines bearing α-tertiary stereocenters with excellent yield and enantioselectivity. The key to success is the rational design of cinchona-alkaloid-based sulfonamides as neutral/anionic hybrid ligands to effectively control the stereochemistry in copper-catalyzed reactions involving free alkyl radical species. The utility of this method is illustrated by efficient transformation of the products into useful chiral CF -containing 1,3-aminoalcohols.
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http://dx.doi.org/10.1002/anie.201804315 | DOI Listing |
J Am Chem Soc
December 2024
Department of Chemistry and the Hong Kong Branch of Chinese National Engineering Research Centre for Tissue Restoration & Reconstruction, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR 999077, China.
Catalytic enantioselective substitution of the readily available racemic α-halo carbonyl compounds by nitrogen nucleophiles represents one of the most convenient and direct approaches to access enantioenriched α-amino carbonyl compounds. Distinct from the two available strategies involving radicals and enolate ions, herein we have developed a new protocol featuring an electronically opposite way to weaken/cleave the carbon-halogen bond. A suitable chiral anion-based catalyst enables effective asymmetric control over the key positively charged intermediates.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Jinan University College of Pharmacy, College of Pharmacy, CHINA.
Highly functionalized xanthenes possess an impressive range of bioactivities and daunting synthetic challenge due to their unique ring systems and stereocenters. Here, we report an unprecedented ketyl radicals-induced skeletal rearrangement reaction of spirodihydrobenzofurans, enabled by zero-valent iron as reducing agents via photoredox catalysis, facilitating the facile preparation of various highly functionalized xanthenes. The features of this protocol include high chemo- and regioselectivity, exceptionally mild conditions, a broad substrate scope, scalability to gram-scale quantities, and consistent delivery of good to excellent yields.
View Article and Find Full Text PDFBrain Res
December 2024
Department of Physiology, Faculty of Medicine, University of Granada, Granada 18071, Spain.
The functional significance of brain asymmetry is still largely unknown. Studying the level of correlation of neuropeptide-degrading activities between subcellular fractions such as synaptosomal, of the left and right hemispheres of male rats during development and aging could provide relevant data on their functional role during these periods. The present study analyzes the level of correlation of a enkephalin- or angiotensin III-degrading activity, such as membrane-bound arginyl-aminopeptidase activity (M-B ArgAP) between the left versus right homogenate and/or synaptosomal subcellular fractions obtained and processed independently from both brain hemispheres during development and aging.
View Article and Find Full Text PDFOrg Lett
December 2024
Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001, India.
Developing asymmetric transformations using electroredox and N-heterocyclic carbene (NHC)-catalyzed radical pathways is still desirable and challenging. Herein, we report an iodide-promoted β-carbon activation (LUMO-lowering process) of enals via electroredox carbene catalysis coupled with a hydrogen evolution reaction (HER). This strategy offers an environmentally friendly and sustainable route for rapidly assembling synthetically useful chiral naphthopyran-3-one in good to excellent yield and enantioselectivity using traceless electrons as inexpensive and greener oxidants.
View Article and Find Full Text PDFOrg Lett
December 2024
Key Laboratory of Environmentally Friendly Chemistry and Application of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan, Hunan 411105, China.
We herein report a photochemical Truce-Smiles rearrangement reaction of -sulfinyl acrylamides with bromodifluoroacetamides resulting in the synthesis of a series of aryl difluoroglutaramides in moderate to good yields. The asymmetric synthesis using chiral sulfinamides produced quaternary carboncentered glutaramide products with a modest enantioselectivity. This protocol effectively complements previous Truce-Smiles rearrangement methods involving -sulfonyl acrylamides.
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