a copper-catalyzed three-component annulation reaction, we herein report a new method for the direct and -selective construction of cyclic ether-fused tetrahydroquinolines from readily available secondary anilines, saturated five or six-membered cyclic ethers, and paraformaldehyde. The synthesis features operational simplicity, excellent step and atom efficiency, good functionality and substrate compatibility. In comparison with the reported synthetic protocols capable of synthesizing -alkyl fused tetrahydroquinolines, this newly developed chemistry allows access to both -alkyl and -aryl products. The current work complements the preparation of fused tetrahydroquinolines.
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http://dx.doi.org/10.1039/d2ob02066a | DOI Listing |
J Am Chem Soc
December 2024
State Key Laboratory of Organometallic Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
The homogeneous catalytic hydrogenation of benzo-fused heteroarenes generally provides partially hydrogenated products wherein the heteroaryl ring is preferentially reduced, such as quinoline hydrogenation, leading to 1,2,3,4-tetrahydroquinoline. Herein, we report a carbocycle-selective hydrogenation of fused -heteroarenes (quinoline, isoquinoline, quinoxaline, etc.) using the Ru complex of a chiral spiroketal-based diphosphine (SKP) as the catalyst, affording the corresponding 5,6,7,8-tetrahydro products in high chemoselectivities.
View Article and Find Full Text PDFNat Commun
November 2024
Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, China.
Palladium-catalyzed directed C - H functionalization/cyclization is an effective approach for synthesizing nitrogen heterocycles. Imine, known for its ease of installation/removal, has been extensively used in the C-H activation of aldehydes, ketones, and alkylamines. Nevertheless, it has been rarely explored in the C(sp)-H activation of aryl amines because of the generation of a strained four-membered palladacycle.
View Article and Find Full Text PDFOrg Lett
November 2024
Hubei Key Laboratory of Natural Products Research and Development, College of Biological and Pharmaceutical Sciences, China Three Gorges University, Yichang, Hubei 443002, China.
Controlling the selectivity of reactions is a significantly attractive strategy in synthetic organic chemistry. Herein, an efficient base-controlled chemodivergent domino reaction between -aminochalcones and bromocrotonates has been developed. A series of -2,3-disubstituted indolines and cyclopropane-fused tetrahydroquinolines were obtained via two pathways with a broad substrate scope in moderate to excellent yields under transition-metal-free conditions.
View Article and Find Full Text PDFJ Org Chem
September 2024
Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), District-Samba, Jammu, Jammu and Kashmir 181143, India.
Palladium-catalyzed regiocontrolled intramolecular oxypalladation-initiated cascades of multifunctional internal alkyne bearing an -tosyl tether deliver functionalized benzazepine as an exclusive product via 6- pathway in 1,4-dioxane solvent and tetrahydroquinoline scaffold as a major product via the 5- pathway in the DMSO solvent. The role of the solvent in controlling the regioselectivity is still unknown which can be a major hurdle for further reaction development. Moreover, the reaction in DMSO suffered from having a mixture of products, and no exclusive formation of tetrahydroquinoline was achieved.
View Article and Find Full Text PDFBMC Chem
August 2024
Department of Chemistry, Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006, Russian Federation.
Currently, there is a growing interest in the synthesis of heterocyclic compounds containing hydroquinoline fragments. This surge can be attributed to the broad range of pharmaceutical and industrial applications that these compounds possess. In this study, the synthesis of both linear and fused heterocyclic systems that incorporate hydroquinoline fragments was described.
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