Catalytic asymmetric 1,2-allylation of aurone-derived azadienes is very difficult to achieve due to the driving force for aromatization and the greater steric hindrance of 1,2-addition compared with 1,4-addition. By taking advantage of the ability of nitrogen ligated metal complexes, we successfully demonstrated the first example of copper-catalyzed 1,2-allylation of azadienes with allylboronates for the highly enantioselective synthesis of homoallylic amines. Meanwhile, the enantioenriched 1,4-addition products could also be obtained through a subsequent 3,3-sigmatropic rearrangement of the 1,2-addition products. Extensive DFT calculations were carried out to elucidate the origins of high regioselectivity (1,2- vs 1,4-) and enantioselectivity.
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http://dx.doi.org/10.1021/acs.orglett.4c00869 | DOI Listing |
Beilstein J Org Chem
December 2024
Departamento de Química Orgánica y Química Inorgánica, Instituto de Investigación Química "Andrés M. del Río" (IQAR), Universidad de Alcalá (IRYCIS), 28805 Madrid, Spain.
Asymmetric cycloaddition is a straightforward strategy which enables the synthesis of structurally distinct cyclic derivatives which are difficult to access by other methodologies, using an efficient and atom-economical path from simple precursors. In recent years several asymmetric catalytic cyclization strategies have been accomplished for the construction of -heterocycles using various catalytic systems such as chiral metal catalysts, chiral Lewis acids or chiral organocatalysts. This review presents an overview of the recent advances in enantioselective cyclization reactions of 1-azadienes catalyzed by non-covalent organocatalysts.
View Article and Find Full Text PDFJ Org Chem
December 2024
Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, College of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637002, China.
A copper catalyzed enantioselective formal aza-Diels-Alder reaction of formed 1,2-diaza-1,3-dienes from α-halohydrazones and vinyl diazo compounds was described. The protocol provides a variety of optically enriched diazo-containing tetrahydropyridazines in moderate yields and with up to excellent enantioselectivities. The present methodologies utilize chiral oxazolines as the chiral ligands for asymmetric catalysis and feature mild reaction conditions, readily available substrates, and broad substrate scope.
View Article and Find Full Text PDFJ Am Chem Soc
November 2024
Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Key Laboratory of Research and Development for Natural Products; School of Pharmacy, Yunnan University, Kunming 650500, P. R. China.
New methods for the enantioselective synthesis of N-alkylated indoles and their derivatives are of great interest because indoles are pivotal structural elements in biologically active molecules and natural products. They are also versatile intermediates in organic synthesis. Among well-established asymmetric hydroamination methods, the asymmetric hydroamination with indole-based substrates is a formidable challenge.
View Article and Find Full Text PDFOrg Lett
December 2024
Department of Chemical Sciences, IISER Kolkata, Mohanpur Campus, Kalyani, Nadia 741 246, West Bengal, India.
(+)-Brevianamides A () and B () are distinguished by their unique bicyclo[2.2.2]diazaoctane structure and have captured the interest of synthetic chemists due to their fascinating array of biological activities.
View Article and Find Full Text PDFOrg Lett
October 2024
Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, Tianjin Key Laboratory of Drug Targeting and Bioimaging, School of Chemistry & Chemical Engineering, Tianjin University of Technology, Tianjin 300384, People's Republic of China.
A novel three-component [4 + 3] annulation reaction of isatin-derived azomethine ylides with azadienes was developed for the first time to efficiently synthesize spirooxindole-diazepines incorporating a benzothiophene moiety under catalyst-free conditions. Effects of the heteroatom of azadiene on the chemoselectivity was investigated. With the use of the azadiene bearing a benzofuran moiety as a substrate, the dominant reaction pathway was changed to an α-[3 + 2] annulation.
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