A copper-promoted divergent intermolecular [2 + ] heteroannulation of β-CF-1,3-enynes with alkyl azides via alkyl radical-driven HAT and radical substitution (C-C bond formation) to form four- to ten-membered saturated -heterocycles is developed. This method enables the aryl-induced or kinetically controlled site selective functionalization of the remote C(sp)-H bonds at positions 2, 3, 4, 5, 6, 7, or 8 toward the nitrogen atom through triplet nitrene formation, radical addition across the C═C bond, HAT and radical substitution cascades, and features a broad substrate scope, excellent site selectivity, and facile late-stage derivatization of bioactive molecules. Initial deuterium-labeling and control experiments shed light on the reaction mechanism via nitrene formation and HAT.
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http://dx.doi.org/10.1021/acs.orglett.3c04041 | DOI Listing |
Int J Biol Macromol
December 2024
INFN-Laboratori Nazionali di Frascati, 00044 Frascati, Italy.
This study investigates the synthesis of corn starch nanocrystals (SNCs) via sulfuric acid hydrolysis. Esterification of oleic acid (OA) with SNCs was carried out using Maghnite-H as a catalyst, a non-polluting, eco-friendly proton-exchanged montmorillonite-based green catalyst suitable for various chemical processes. Optimization of synthesis parameters, including reaction temperature, duration, and catalyst quantity, was conducted using response surface methodology (RSM) with a central composite design incorporating three factors and three levels.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Tianjin University, Phamaceutical Engineering, Weijin Road NO.92, 300072, Tianjin, CHINA.
Fluorine and fluorine-containing functional groups play important roles in drugs and agrochemicals. Recently, SAM-dependent methyltransferases and several SAM analogues have been reported for fluoromethyl transfer through a nucleophilic mechanism. However, fluoromethylation of unactivated carbon centers is very challenging, and their substitution usually involves a radical mechanism.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.
We present a six-step cascade that converts 1,3-distyrylbenzenes (-stilbenes) into nonsymmetric pyrenes in 40-60% yields. This sequence merges photochemical steps, ,-alkene isomerization, a 6π photochemical electrocyclization (Mallory photocyclization); the new bay region cyclization, with two radical iodine-mediated aromatization steps; and an optional aryl migration. This work illustrates how the inherent challenges of engineering excited state reactivity can be addressed by logical design.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., Moscow 119991, Russian Federation.
The selective reaction of cyclic aminoperoxides with FeCl proceeds through a sequence of O-O and C-C bond cleavages, followed by intramolecular cyclization, yielding functionalized tetrahydrofurans in 44-82% yields. Replacing the peroxyacetal group in the peroxide structure with a peroxyaminal fragment fundamentally alters the reaction pathway. Instead of producing linear functionalized ketones, this modification leads to the formation of hard-to-access substituted tetrahydrofurans.
View Article and Find Full Text PDFJ 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.
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