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A copper-catalyzed [3+2] annulation reaction of exocyclic enamines/enol ethers with 1,4-benzoquinone esters has been developed, providing facile access to N,O-spiroketals and spiroketals under mild conditions with broad substrate scope (26 examples, 71-94 % yields). Gram scale synthesis and chemical transformations demonstrated that this method is potentially useful in the synthesis of natural products and drugs containing a N,O- spiroketal moiety. The chiral N,O-spiroketal could be obtained with 98 % ee after recrystallization, when a chiral SaBOX ligand was employed.
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http://dx.doi.org/10.1002/chem.202401062 | 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.
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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.
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September 2025
Jiangxi Province Key Laboratory of Natural and Biomimetic Drugs Research, College of Chemistry and Materials, Jiangxi Normal University, Nanchang 330022, China.
The annulation reaction of β-methyl enaminones with alkynones leading to the synthesis of methylene-functionalized 1,2-dihydropyridines (1,2-DHPs) has been realized. In the presence of only CsCO, 1,2-DHPs have been synthesized with a broad scope and generally high efficiency via the novel transformation of the γ-C(sp)-H bond in enaminones. In addition, the application of the method has been demonstrated by the one-step transformation of the 1,2-DHP products into fused tricyclic scaffolds featuring an indole-pyridine hybrid via dual C-H activation.
View Article and Find Full Text PDFOrg Biomol Chem
September 2025
Department of Chemistry, National Institute of Technology Calicut, 673601, Kozhikode, Kerala, India.
We report here an efficient and sustainable protocol for the direct synthesis of 2,3-dihydroperimidine derivatives dehydrogenative C-N coupling, utilizing a recyclable Fe single-atom catalyst supported on nitrogen-doped carbon (Fe-N-C). The catalyst was synthesized by encapsulating ferrocene within the ZIF-8 framework, followed by pyrolysis. The catalyst exhibited excellent activity, stability, and recyclability, facilitating the transformation of diverse primary alcohols, including aryl/heteroaryl methanol and aliphatic alcohols, into the desired products in moderate to good yields.
View Article and Find Full Text PDFChem Commun (Camb)
September 2025
Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India.
A CFOH-catalysed tandem cyclization of -alkynylnaphthols and -quinone monoketals is disclosed. The CFOH catalyst activates alkynylnaphthol to generate an all-carbon tetrasubstituted VQM by nucleophilic addition to quinone monoketal (Michael addition). Furthermore, the CFOH catalyst triggers -quinone monoketal to generate an electrophilic oxocarbenium cation to be captured by -alkynylnaphthol regiospecifically, resulting in the formation of an all-carbon tetrasubstituted VQM, followed by an intramolecular cyclization to afford a series of 1-(3-arylbenzofuran-2-yl)naphthalen-2-ols.
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