Electroreductive C3 Pyridylation of Quinoxalin-2(1H)-ones: An Effective Way to Access Bidentate Nitrogen Ligands

Electrochemical Ammonium Cation‐Assisted Hydropyridylation of Ketone‐Activated Alkenes: Experimental and Computational Mechanistic Studies

“…However, only trace amounts of products were produced when C3 of 4-cyanopyridine was substituted with a Me, F, or Cl group under the present electrochemical conditions, which may be related to substituent and electronic effect (31 c). [12] Unfortunately, no desired products 32 c-35 c were observed due to the inherently more negative reducing electrode potential of raw materials (the CV results see Supporting Information, Figure S6b), which resulted in the inability to perform PCET events and couple with INT8.…”

Electrochemical ammonium-cation-assisted pyridylation of inert N-heterocycles via dual-proton-coupled electron transfer

“…Subsequently, the scope of the cyanopyridines was investigated by employing acridine as a benchmark. To our delight, the desired products 3sc and 3sd can be delivered smoothly when 2-fluoroisonicotinonitrile and 3-chloroisonicotinonitrile were executed under current condition, which was difficult to achieve in previous reports ( Xu et al., 2021 ; Zhang et al., 2020 , 2021 ; Lehnherr et al., 2020 ; Wen et al., 2021 ). Besides, a variety of 2-cyanopyridine derivatives can also be compatible with the present protocol and deliver the corresponding products with good yields ( 3se – 3sb ).…”

“…In recent years, multifarious important pyridine-containing functional molecules have been constructed based on the decyanation of cyanopyridines mediated by electrochemical reduction ( Xu et al., 2021 ; Zhang et al., 2020 , 2021 ; Lehnherr et al., 2020 ; Wen et al., 2021 ). Previously, we have delivered the C3 pyridylation of quinoxalin-2(1H)-ones with readily available cyanopyridines under the electrochemical conditions by employing HFIP as the protonation reagent ( Scheme 1 C) ( Wen et al., 2021 ). However, we found that the pyridylation of electron-deficient quinolines cannot be achieved by adopting the previous protocol.…”

Visible Light-Promoted Radical Relay Cyclization/C–C Bond Formation of N-Allylbromodifluoroacetamides with Quinoxalin-2(1H)-ones

“…Quinoxalin-2­(1 H )-ones are widely present in numerous bioactive natural products and pharmaceuticals because of their significant biological activities and outstanding chemical properties (Scheme a). , Direct functionalization of quinoxalin-2­(1 H )-ones, especially at the C3 position, is a convenient method to expand their structural diversity. In recent years, impressive advances have been made to access 3-substituted quinoxalin-2­(1 H )-ones through transition-metal-catalyzed or visible light-induced functionalization, including arylation, acylation, phosphonation, amination, or trifluoromethylation (Scheme a) . Despite that a range of functionalized quinoxalin-2­(1 H )-ones have been prepared, the structural complexity and chemical space for this class of hetereocycles are still highly expected to be expanded by exploiting new synthetic pathways.…”