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The fragile intermediates of the domino process leading to an isoxazolidin-5-one, triggered by unique reactivity between Meldrum's acid and an N-benzyl nitrone in the presence of a Brønsted base, were determined thanks to the softness and accuracy of electrospray ionization mass spectrometry coupled to ion mobility spectrometry (ESI-IMS-MS). The combined DFT study shed light on the overall organocatalytic sequence that starts with a stepwise (3+2) annulation reaction that is followed by a decarboxylative protonation sequence encompassing a stereoselective pathway issue.
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http://dx.doi.org/10.1002/chem.201705714 | DOI Listing |
Org Lett
September 2025
Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan 650500, P. R. China.
An iron(III)-catalyzed methanesulfonic-acid-mediated [3 + 2 + 1C] annulation of enaminones assembling a 1,2-dihydropyridine (1,2-DHP) scaffold has been developed for the first time. This approach facilitates the rapid synthesis of 2-hydroxy-1,2-DHP derivatives in moderate to excellent yields with a broad substrate scope under mild conditions. The employment of 1,3-dioxolane as both a 1C synthon and solvent enables simultaneous incorporation of both a carbon atom and a hydroxy group into 1,2-DHPs.
View Article and Find Full Text PDFOrg Lett
September 2025
Henan Provincial Engineering and Technology Research Center for Precise Synthesis of Fluorine-Containing Drugs. College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, 455000, P. R. China.
In this work, we report a novel I-mediated ring-opening -difunctionalization of cyclopropyl alcohols with enaminones for the first time. The selective [3 + 2] annulation instead of [3 + 3] annulation under metal-free conditions enables a straightforward and efficient synthesis of structurally important 2,4-diacylpyrroles. Notably, this methodology dispenses with metal catalysts, proceeds under mild reaction conditions, and features not only simple operation but also suitability for gram-scale preparation and late-stage functionalization of complex bioactive molecules.
View Article and Find Full Text PDFPrecis Chem
August 2025
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 999077, Hong Kong SAR, China.
A silver-catalyzed intermolecular (3 + 2) annulation of siloxy alkynes and 3-aminooxetanes has been developed. This process provides mild and convenient access to useful γ-butyrolactams with high regio- and stereoselectivity. Mechanistically, intermolecular C-N bond formation likely precedes oxetane ring opening.
View Article and Find Full Text PDFChem Asian J
August 2025
Department of Chemistry, National Institute of Technology Tiruchirappalli, Tiruchirappalli, Tamil Nadu, 620015, India.
Pd-catalyzed straight forward [3+2] cycloaddition reaction between spirovinylcyclopropyl-2-oxindole and coumarin/bioisosteres is demonstrated. The resultant products spirooxindolyl-cyclopentane[c]chromanones and structural analogues are obtained in up to 97% yields and > 99:1 dr. The target spirooxindole-cyclopentane architectures with four contiguous stereocenters with high diastereocontrol is differentially influenced by inexpensive 2,2'-bipyridyl ligand and greener solvent EtOH.
View Article and Find Full Text PDFJ Org Chem
September 2025
Department of Chemistry, China Agricultural University, Beijing 100193, P. R. China.
This study presents a phosphine-catalyzed [3 + 2] annulation of sulfamidate imine-derived 1-azadienes with Morita-Baylis-Hillman (MBH) carbonates or allenoates, affording densely functionalized spiro[oxathiazole-cyclopentene] architectures under mild reaction conditions in generally high yields and excellent diastereoselectivities. Through a reductive ring contraction sequence of the spirocyclic thiosulfamide, valuable spirocyclic aziridine derivatives were accessed conveniently via both two-step and one-pot protocols.
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