- Unveiling Potent Photooxidation Behavior of Catalytic Photoreductants
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We describe a photocatalytic system that reveals latent photooxidant behavior from one of the most reducing conventional photoredox catalysts, N-phenylphenothiazine (PTH). This aerobic photochemical reaction engages difficult to oxidize feedstocks, such as benzene, in C(sp2)-N coupling reactions through direct oxidation. Mechanistic studies are consistent with activation of PTH via photooxidation and with Lewis acid cocatalysts scavenging inhibitors inextricably formed in this process.
- Targos, Karina,Williams, Oliver P.,Wickens, Zachary K.
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supporting information
p. 4125 - 4132
(2021/04/07)
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- Electrophotocatalysis with a Trisaminocyclopropenium Radical Dication
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Visible-light photocatalysis and electrocatalysis are two powerful strategies for the promotion of chemical reactions. Here, these two modalities are combined in an electrophotocatalytic oxidation platform. This chemistry employs a trisaminocyclopropenium (TAC) ion catalyst, which is electrochemically oxidized to form a cyclopropenium radical dication intermediate. The radical dication undergoes photoexcitation with visible light to produce an excited-state species with oxidizing power (3.33 V vs. SCE) sufficient to oxidize benzene and halogenated benzenes via single-electron transfer (SET), resulting in C?H/N?H coupling with azoles. A rationale for the strongly oxidizing behavior of the photoexcited species is provided, while the stability of the catalyst is rationalized by a particular conformation of the cis-2,6-dimethylpiperidine moieties.
- Huang, He,Strater, Zack M.,Rauch, Michael,Shee, James,Sisto, Thomas J.,Nuckolls, Colin,Lambert, Tristan H.
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supporting information
p. 13318 - 13322
(2019/08/12)
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- Acetylacetaldehyde Dimethyl Acetal as Versatile Precursors for the Synthesis of Arylazonicotinic Acid Derivatives: Green Multicomponent Syntheses of Bioactive Poly-Heteroaromatic Compounds
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A simple and efficient one-pot synthesis of interesting arylhydrazonals could be achieved via coupling of acetylacetaldehyde dimethyl acetal with aromatic diazonium salts. Dimroth type rearrangement was observed during the reaction of the arylhydrazonals with malononitrile or ethyl cyanoacetate leading to the formation of arylazonicotinic acid derivatives. The reaction of arylhydrazonals with malononitrile and aldehydes in the presence of DABCO afforded 4-styryl-1,2-dihydropyridine-3-carbonitrile whose structure was established by X-ray crystallography. Pyrazolyl-enaminone was accomplished and used as a scaffold to synthesize bioactive fused heterocyclic compounds such as 1,2,4-triazolo[1,5-a]pyrimidine 28, benzo[4,5]imidazo[1,2-a]pyrimidine 30 and pyrazole[1,5-a]pyrimidine derivatives 32.
- Hassaneen, Huwaida M. E.,Abdelhamid, Ismail A.
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p. 1048 - 1053
(2017/03/27)
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- Cycloaddition Reactions of 1-tert-Butyl-4-vinylpyrazole
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1-tert-Butyl-4-vinylpyrazole 1a reacts with dimethyl acetylenedicarboxylate (DMAP), methyl propiolate (MP) and N-phenylmaleimide (NPMI) affording the indazole derivatives 2, 3, and 5 as a result of a Diels-Alder () cycloaddition.With diethylazodicarb
- Sepulveda-Arques, Jose,Medio-Simon, Mercedes,Piqueres-Vidal, Lourdes
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p. 1113 - 1118
(2007/10/02)
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