0000000000466823

AUTHOR

Juho Helaja

showing 3 related works from this author

Intermolecular oxidative dehydrogenative 3,3′-coupling of benzo[b]furans and benzo[b]thiophenes promoted by DDQ/H+: total synthesis of shandougenine B

2016

With an excess of a strong acid, 2,3-dichloro-5,6-dicyano-1,4-quinone (DDQ) is shown to promote metal-free intermolecular oxidative dehydrogenative (ODH) 3,3'-coupling of 2-aryl-benzo[b]furans and 2-aryl-benzo[b]thiophenes up to 92% yield as demonstrated with 9 substrates. Based on the analysis of oxidation potentials and molecular orbitals combined with EPR, NMR and UV-Vis observations, the studied reaction is initiated by a DDQ-substrate charge transfer complex and presumably proceeds via oxidation of the substrate into an electrophilic radical cation that further reacts with another molecule of a neutral substrate. The coupling reactivity can easily be predicted from the oxidation potent…

116 Chemical sciencesEFFICIENTfree radicalscoupling reactionsvapaat radikaalit010402 general chemistryPhotochemistry01 natural sciencesMedicinal chemistryCoupling reactionoxidative dehydrogenationC BOND FORMATIONSCHOLL REACTIONELECTRON-TRANSFERMolecular orbitalReactivity (chemistry)luonnonaineiden synteesiDIPHOSPHINE LIGANDSta116BASIS-SETSCATALYZED STEREOSELECTIVE REACTIONS010405 organic chemistryChemistryOrganic ChemistrykytkentäreaktiotSubstrate (chemistry)Total synthesishapettava dehydroganaatiolaskennallinen kemiaCharge-transfer complex0104 chemical sciencesRadical ionsynthesis of natural productsACIDElectrophileCATION-RADICALSHETEROCYCLESOrganic Chemistry Frontiers
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E-Ring extended estrone derivatives: introduction of 2-phenylcyclopentenone to the estrone D-ring via an intermolecular Pauson–Khand reaction

2006

Abstract An expedient synthetic route to E-ring extended estrone derivatives is reported. Estrone-derived cyclopentenones were accessed by an intermolecular Pauson–Khand (PK) cycloaddition. It was found that electron donating and withdrawing substituents in the arylalkyne increased and decreased the yields of PK products, respectively. The stereochemistry of the products was elucidated by X-ray and NMR studies.

chemistry.chemical_compoundchemistryStereochemistryPauson–Khand reactionOrganic ChemistryDrug DiscoveryIntermolecular forceRegioselectivityEstroneBiochemistryCycloadditionTetrahedron Letters
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Carbocatalytic Oxidative Dehydrogenative Couplings of (Hetero)Aryls by Oxidized Multi‐Walled Carbon Nanotubes in Liquid Phase

2019

HNO3-oxidized carbon nanotubes catalyze oxidative dehydrogenative (ODH) carbon-carbon bond formation between electron-rich (hetero)aryls with O-2 as a terminal oxidant. The recyclable carbocatalytic method provides a convenient and an operationally easy synthetic protocol for accessing various benzofused homodimers, biaryls, triphenylenes, and related benzofused heteroaryls that are highly useful frameworks for material chemistry applications. Carbonyls/quinones are the catalytically active site of the carbocatalyst as indicated by model compounds and titration experiments. Further investigations of the reaction mechanism with a combination of experimental and DFT methods support the compet…

Reaction mechanism116 Chemical sciencesoxidative dehydrogenative couplingLiquid phaseOxidative phosphorylationCarbon nanotube010402 general chemistryHeterogeneous catalysis01 natural sciencesCatalysislaw.inventionlawcarbon nanotubecarbon nanotubesbiology010405 organic chemistryChemistryOrganic ChemistryC−C couplingCationic polymerizationcarbon nanotubes; C−C coupling; heterogeneous catalysis; oxidative dehydrogenative couplingActive siteGeneral ChemistryCombinatorial chemistry0104 chemical sciencesheterogeneous catalysisbiology.proteinheterogeneous catalysiTitrationC-C couplingChemistry – A European Journal
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