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A visible-light-driven deoxygenative [3 + 2] annulation between α,β-unsaturated carbonyl compounds and electron-rich olefins was developed, which proceeded under mild conditions with a broad substrate scope and functional group tolerance, enabling straightforward access to diverse substituted cyclopentenes. This cascade annulation strategy exploited the reactivity of phosphine radical cations, generated from triarylphosphines by the oxidation with the excited-state iridium-based photocatalysts, toward olefins to form the corresponding distonic radical cations with a chain length pertinent to constructing cyclopentene scaffolds via sequential radical addition and intramolecular Wittig reaction.
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http://dx.doi.org/10.1021/jacs.5c06114 | DOI Listing |
J Am Chem Soc
July 2025
Institute of Transformative Bio-Molecules (WPI-ITbM), and Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8601, Japan.
A visible-light-driven deoxygenative [3 + 2] annulation between α,β-unsaturated carbonyl compounds and electron-rich olefins was developed, which proceeded under mild conditions with a broad substrate scope and functional group tolerance, enabling straightforward access to diverse substituted cyclopentenes. This cascade annulation strategy exploited the reactivity of phosphine radical cations, generated from triarylphosphines by the oxidation with the excited-state iridium-based photocatalysts, toward olefins to form the corresponding distonic radical cations with a chain length pertinent to constructing cyclopentene scaffolds via sequential radical addition and intramolecular Wittig reaction.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Organisch-Chemisches Institut, Universität Münster, 48149, Münster, Germany.
Oxidatively generated phosphine radical cations are reactive intermediates that can be used for the generation of carbon and heteroatom centered radicals via deoxygenation processes. Such P-radical cations can readily be generated via single electron transfer oxidation using a redox catalyst. Cheap and commercially available nitroarenes are ideal nitrogen sources for the construction of organic amines and N-containing heterocycles.
View Article and Find Full Text PDFJ Am Chem Soc
January 2023
Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
A synthetic method for the reductive transformation of nitroarenes into -aminated and -annulated products is reported. The method operates via the exhaustive deoxygenation of nitroarenes by an organophosphorus catalyst and a mild terminal reductant to access aryl nitrenes, which after ring expansion, are trapped by amine nucleophiles to give dearomatized 2-amino-3-azepines. Treatment of these ring-expanded intermediates with acyl electrophiles triggers 6π electrocyclization to extrude the nitrogen atom and restore aromaticity of the phenyl ring, which delivers via C-H functionalization 2-aminoanilide and benzimidazole products.
View Article and Find Full Text PDFChemistry
December 2022
School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
The dolabellane-type diterpene dictyoxetane represents a significant challenge to synthetic organic chemistry. Methodology directed towards the total synthesis of naturally occurring (+)-dictyoxetane is reported. Catalytic asymmetric synthesis of the trans-hydrindane ring system is achieved through chemoselective deoxygenation of the Hajos-Parrish ketone.
View Article and Find Full Text PDFOrg Biomol Chem
July 2022
N. D. Zelinsky Institute of Organic Chemistry, 119991, Leninsky prospect, 47, Moscow, Russian Federation.
In this work, the classical "isoxazoline route" toward aldols involving the [3 + 2]-cycloaddition of nitrile oxide to alkenes and hydrogenolysis of the oxime group was revisited. To avoid regioselectivity issues, [4 + 1]-annulation of nitroalkenes with sulfonium ylides was used to construct the isoxazoline ring bearing an -oxide moiety. Subsequent deoxygenative C-H functionalization using the Boekelheide rearrangement and hydrogenolysis of the isoxazoline ring afforded α'-acyloxy-substituted aldols, which are difficult to access both by the classical aldol reaction and the "isoxazoline route".
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