155395-45-2Relevant articles and documents
Carbazole based Electron Donor Acceptor (EDA) catalysis for the synthesis of biaryl and aryl-heteroaryl compounds
Annes, Sesuraj Babiola,Ramesh, Subburethinam,Saravanan, Subramanian,Saritha, Rajendhiran
supporting information, p. 2510 - 2515 (2020/04/15)
A highly regioselective, carbazole based Electron Donor Acceptor (EDA) catalyzed synthesis of biaryl and aryl-heteroaryl compounds is described. Various indole and carbazole derivatives were screened for the Homolytic Aromatic Substitution (HAS) reaction. Tetrahydrocarbazole (THC) was very efficient for the HAS transformation and proceeded via a complex formation between diazonium salt and electron rich tetrahydrocarbazole. The UV-Vis spectroscopy technique has been used to confirm the complex formation. The in situ generated EDA complex even in a catalytic amount is found to be efficient for the Single Electron Transfer (SET) process without any photoactivation. Biaryl compounds, 2-phenylfuran, 2-phenylthiophene, and 2-phenylpyrrole and bioactive compounds such as dantrolene and canagliflozin have been synthesized in moderate to excellent yields.
Molecular Design of Donor-Acceptor-Type Organic Photocatalysts for Metal-free Aromatic C?C Bond Formations under Visible Light
Wang, Lei,Byun, Jeehye,Li, Run,Huang, Wei,Zhang, Kai A. I.
, p. 4312 - 4318 (2018/10/02)
Metal-free and photocatalytic radical-mediated aromatic C?C bond formations offer a promising alternative pathway to the conventional transition metal-catalyzed cross-coupling reactions. However, the formation of aryl radicals from common precursors such as aryl halides is highly challenging due to their extremely high reductive potential. Here, we report a structural design strategy of donor-acceptor-type organic photocatalysts for visible light-driven C?C bond formations through the reductive dehalogenation of aryl halides. The reduction potential of the photocatalysts could be systematically aligned to be ?2.04 V vs. SCE via a simple heteroatom engineering of the donor-acceptor moieties. The high reductive potential of the molecular photocatalyst could reduce various aryl halides into aryl radicals to form the C?C bond with heteroarenes. The designability of the molecular photocatalyst further allowed the synthesis of a high LUMO (lowest unoccupied molecular orbital) polymer photocatalyst by a self-initiated free radical polymerization without compromising its LUMO level. (Figure presented.).
Anthraquinones as Photoredox Catalysts for the Reductive Activation of Aryl Halides
Bardagi, Javier I.,Ghosh, Indrajit,Schmalzbauer, Matthias,Ghosh, Tamal,K?nig, Burkhard
supporting information, p. 34 - 40 (2018/01/01)
Quinones are ubiquitous in nature as structural motifs in natural products and redox mediators in biological electron-transfer processes. Although their oxidation properties have already been used widely in chemical and photochemical reactions, the applications of quinones in reductive photoredox catalysis are less explored. We report the visible-light photoreduction of aryl halides (Ar–X; X = Cl, Br, I) by 1,8-dihydroxyanthraquinone. The resulting aryl radical anions fragment into halide anions and aryl radicals, which react through hydrogen abstraction or C–C bond-forming reactions. The active photocatalyst is generated from 1,8-dihydroxyanthraquinone by photoinduced single-electron reduction to the radical anion or subsequent protonation and further reduction (or vice versa) to the semiquinone anion. Subsequent visible-light excitation of the anthraquinone radical anion or semiquinone anion converts them into very potent single-electron donors. A plausible mechanism for the reaction is proposed on the basis of control experiments and spectroscopic investigations.
