Unusual Lewis-acid catalyzed formal (3+3)-cycloaddition of azomethine imines and nitrones to N-vinylpyrroles
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DOI: 10.1016/j.tet.2016.12.034
Abstract: Abstract The addition of Lewis acids change the reaction mechanism of the cycloaddition of N-vinylpyrroles with azomethine imine and C,N-diarylnitrones. The formal (3+3)-cycloaddition is observed instead of (3+2)-dipolar cycloaddition, which take place in the absence… read more here.
Keywords: cycloaddition; lewis acid; unusual lewis; formal cycloaddition ... See more keywords
Catalytic Ynone-Amidine Formal [4 + 2]-Cycloaddition for the Regioselective Synthesis of Tricyclic Azepines.
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DOI: 10.1021/acs.orglett.0c03711
Abstract: A Ca(OTf)2- and self-promoted ynone-amidine atom-economic formal [4 + 2]-cycloaddition of various ynones with amidines is reported for the construction of highly functionalized tricyclic azepines. High reaction rate, ease of operation, and high product selectivity… read more here.
Keywords: ynone amidine; formal cycloaddition; tricyclic azepines; amidine formal ... See more keywords
B(C6F5)3-Catalyzed Diastereoselective Formal (4 + 1)-Cycloaddition of Vinylcyclopropanes and Et2SiH2.
Sign Up to like & getrecommendations! Published in 2021 at "Organic letters"
DOI: 10.1021/acs.orglett.1c01565
Abstract: A formal (4 + 1)-cycloaddition of vinylcyclopropanes and Et2SiH2 to afford 3,4-disubstituted silolanes is reported. The reaction sequence commences with the known B(C6F5)3-catalyzed alkene hydrosilylation with dihydrosilanes. Cleavage of the remaining Si-H bond in the… read more here.
Keywords: c6f5 catalyzed; catalyzed diastereoselective; formal cycloaddition; cycloaddition vinylcyclopropanes ... See more keywords
Base-Promoted Formal [3 + 2] Cycloaddition of α-Halohydroxamates with Carbon Disulfide to Synthesize Polysubstituted Rhodanines.
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DOI: 10.1021/acs.orglett.2c00736
Abstract: A concise and practical strategy via potassium-carbonate-mediated [3 + 2]-cycloaddition reaction of α-halohydroxamates with the common solvent carbon disulfide for the synthesis of functionalized rhodanine derivatives in good to excellent yields is developed. The present… read more here.
Keywords: base promoted; promoted formal; carbon disulfide; cycloaddition halohydroxamates ... See more keywords
Chiral Brønsted Acid Catalyzed Enantioselective Synthesis of Spiro-Isoindolinone-Indolines via Formal [3 + 2] Cycloaddition.
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DOI: 10.1021/acs.orglett.2c00748
Abstract: A novel organocatalytic asymmetric formal [3 + 2] cycloaddition of 3-substituted 1H-indoles with in situ generated 3-hydroxy-isoindolinone-derived β,γ-alkynyl-α-ketimines has been developed. A variety of biologically relevant chiral spiro-isoindolinone-indolines were achieved with excellent yields (up to… read more here.
Keywords: isoindolinone; spiro isoindolinone; isoindolinone indolines; formal cycloaddition ... See more keywords
A Formal (4 + 2) Cycloaddition of Phosphorus Ylides: Synthesis of Aromatic and Heteroaromatic 1,2-Diesters and Diones.
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DOI: 10.1021/acs.orglett.2c01234
Abstract: Heteroarylmethylenephosphorus ylides underwent Michael addition with alkynediones and alkynediesters, followed by intramolecular cyclization and elimination of triphenylphosphine oxide to afford 1,2-diaroylbenzenes and 1,2-alkoxycarbonylcarbo- and heterocycles. The analogous (4 + 2) cycloaddition led to the formation… read more here.
Keywords: phosphorus ylides; ylides synthesis; cycloaddition phosphorus; formal cycloaddition ... See more keywords
Phosphine-Catalyzed Atroposelective Formal [3 + 2] Cycloaddition Desymmetrization of N-Arylmaleimides.
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DOI: 10.1021/acs.orglett.2c02208
Abstract: Herein, a new strategy for the enantioselective synthesis of axially chiral N-aryl succinimides was devised by [3 + 2] annulation of MBH carbonates and N-aryl maleimides under chiral phosphine. This desymmetrization process allows for quick… read more here.
Keywords: phosphine catalyzed; cycloaddition desymmetrization; atroposelective formal; formal cycloaddition ... See more keywords
A Traceless Heterocyclic Amine Mediator in Regioselectivity-Switchable Formal [1 + 2 + 2] Cycloaddition Reaction to 1,3,4- and 1,4,5-Trisubstituted Pyrazoles.
Sign Up to like & getrecommendations! Published in 2023 at "Organic letters"
DOI: 10.1021/acs.orglett.2c04227
Abstract: Switchable multicomponent reactions have been attractive tools for the construction of compound libraries with skeleton diversity and complexity by slightly changing the reaction conditions. Described herein is a regioselectivity-switchable formal [1 + 2 + 2]… read more here.
Keywords: reaction; regioselectivity; switchable formal; regioselectivity switchable ... See more keywords
Gold-Catalyzed Formal [3 + 2] Cycloaddition of Ynamides with 4,5-Dihydro-1,2,4-oxadiazoles: Synthesis of Functionalized 4-Aminoimidazoles.
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DOI: 10.1021/acs.orglett.7b01469
Abstract: A gold-catalyzed formal [3 + 2] cycloaddition of ynamides with 4,5-dihydro-1,2,4-oxadiazoles has been developed. The reaction provides a concise and regioselective access to highly functionalized 4-aminoimidazoles likely via the formation of an α-imino gold carbene… read more here.
Keywords: dihydro oxadiazoles; ynamides dihydro; formal cycloaddition; catalyzed formal ... See more keywords
Asymmetric Formal [3 + 2]-Cycloaddition of Azomethine Imines with Azlactones To Synthesize Bicyclic Pyrazolidinones.
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DOI: 10.1021/acs.orglett.7b02772
Abstract: An efficient enantioselective formal [3 + 2]-cycloaddition of azomethine imines with azlactones has been realized by using a chiral bifunctional bisguanidinium hemisalt as the catalyst. Optically active bicyclic pyrazolidinone compounds were generated under mild reaction… read more here.
Keywords: formal cycloaddition; imines azlactones; azomethine imines; cycloaddition azomethine ... See more keywords
Stereocontrolled Synthesis of (±)-Melokhanine E via an Intramolecular Formal [3 + 2] Cycloaddition.
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DOI: 10.1021/acs.orglett.9b04546
Abstract: A convergent sequence to access the indole alkaloid (±)-melokhanine E in 12-steps (8-step longest linear sequence) and an 11% overall yield is reported. The approach utilizes two cyclopropane moieties as reactive precursors to a 1,3-dipole… read more here.
Keywords: synthesis melokhanine; formal cycloaddition; melokhanine; melokhanine via ... See more keywords