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Seven-membered polycyclic architectures, widely present in natural products and molecular drugs, are challenging synthetic targets. However, methods for synthesizing fused medium-sized bicyclo[..0] ring systems, including the benzo-cycloheptane systems, are still urgent. Herein we describe a base-induced ring expansion as a general strategy to construct a wide range of fused seven-membered ring systems. The application of this method was demonstrated by the efficient total syntheses of two sesquiterpenoids, plecarpenene and plecarpenone, both bearing a fused bicyclo[5.3.0]decane skeleton.
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http://dx.doi.org/10.1021/acs.orglett.2c01401 | DOI Listing |
Chem Commun (Camb)
September 2025
CSIR-Central Drug Research Institute Lucknow, 226031, India.
α-Diazo compounds have long been recognized as versatile reagents in organic synthesis, traditionally employed in metallocarbene chemistry. Recent advances have expanded their scope beyond conventional carbene-based transformations, leading to diverse applications in heterocycle synthesis and functionalization strategies. This review highlights the evolution of α-diazo compounds as key reagents in modern synthetic methodologies, focusing on their unique reactivity patterns, including cycloadditions, homologations, ring expansions, and carbene-free functionalizations.
View Article and Find Full Text PDFOrg Lett
September 2025
School of Chemistry and Chemical Engineering/Institute of Clean Energy and Materials/Guangzhou Key Laboratory for Clean Energy and Materials, Guangzhou University, Guangzhou 510006, P. R. China.
The facile synthesis of indole-fused diazepinones via Rh(III)-catalyzed [4 + 3] annulation of indole derivatives with cyclopropyl alcohol by merging sequential C-H and C-C bond cleavage has been realized. Notably, the eight-membered diazocino[7,8,1-]indol-5-ones and seven-membered azepino[3,4-]indol-1(2)-ones could also be obtained via this tandem reaction strategy. This catalytic approach features mild reaction conditions, readily accessible starting materials, valuable products, and excellent atom-economy.
View Article and Find Full Text PDFEur J Med Chem
August 2025
School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing, 211816, Jiangsu, China; Xitaihu Lake Industrial College, Nanjing Tech University, Changzhou, 213149, Jiangsu, China. Electronic address:
The diterpene andrographolide, a nature-derived product, exerts a wide range of pharmacological effects, including anti-inflammatory, antiviral, immunostimulatory, and anticancer activities, due to its ability to target multiple pathways. In this study, some andrographolide derivatives of an enlarged decalin structure with a seven-membered ring or an isoxazole-fused decalin structure were designed, synthesized, and evaluated for their activity against cancer cell growth and angiogenesis. Among them, compound AGW-11 (designated as compound 8) showed potent and broad-spectrum anticancer activity and anti-angiogenic activity in vitro.
View Article and Find Full Text PDFOrg Lett
August 2025
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510, Japan.
The synthesis and properties of a fused Koelsch radical derivative incorporating a seven-membered ring are described. The strategic incorporation of a heptagon into the extended π-system was hypothesized to enable access to multiple persistent redox states by synergistically controlling the local aromaticity. Consequently, three persistent redox states (cation, neutral radical, and anion) of the compound were generated and characterized.
View Article and Find Full Text PDFJ Comput Chem
July 2025
Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), S. A. S. Nagar, Punjab, India.
Cyclic nitrenium ions (CNIs) with five and seven-membered rings are well known, but the CNIs with six-membered rings are rare. Only a few are known as peri-fused six-membered cyclic nitrenium ions (PCNIs) and they are reported to be nitrogen Lewis acids. Preliminary electronic structure analysis indicated that the electronic properties of PCNIs somewhat deviate from the other CNIs (five or seven-membered).
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