Pd-Catalyzed Redox-Neutral C–N Coupling Reaction of Iminoquinones with Electron-Deficient Alkenes without External Oxidants: Access of Tertiary (E)-Enamines and Application to the Synthesis of Indoles and Quinolin-4-ones

Abstract

A novel and efficient reductive N-alkenylation of iminoquinones with electron-deficient olefins has been successfully developed by Pd­(II)-catalyzed redox-neutral reactions, which provides a synthesis of tertiary (E)-enamines. We further demonstrate that the tertiary enamines can be converted to multifarious N-heterocyclic compounds, indoles, and quinolones in good yields.

Exploiting Iminoquinones as Electrophilic at Nitrogen “N+” Synthons for C–N Bond Construction

“…Iminoquinones represent a class of “N+” synthons that has been only sparsely evaluated, − and no general approach for the exploitation of these intermediates has been developed . In this work, we show that iminoquinones (Scheme ), readily accessed by the condensation of alkyl- or arylamines with 1,4-benzoquinones, display electrophilic character at nitrogen.…”

Palladium-Catalyzed N-Alkenylation of N-Aryl Phosphoramidates with Alkenes

“…In recent years, palladium-catalyzed intermolecular oxidative amination of alkenes with anilines has been used to synthesize complex enamines [10][11][12][13], but it is unsuitable for electron-deficient aniline. Metal-catalyzed direct alkenylation of N-aryl phosphoramidates with alkenes represents a significant but challenging assignment, mainly due to the special structural characteristics of the N-aryl phosphoramidates.…”

Cu‐Catalyzed Chan–Evans–Lam Coupling Reactions of 2‐Nitroimidazole with Aryl Boronic Acids: An Effort toward New Bioactive Agents against S. pneumoniae

“…[1 -4] Five-membered heterocycles, like imidazole, are commonly observed in pharmaceuticals and natural products, which show antifungal, antitumor, antibacterial, and anti-inflammatory activity. [5][6][7] More specifically, a plethora of pharmaceuticals contains N-phenylimidazole moieties. [8,9] Several FDA approved therapeutics that contain this or related architectures are shown in Figure 1; they include clonidine (sedative and antihypertensive drug), alpidem (anxiolytic drug), zolimidine (gastroprotective drug), olprinone (cardiotonic agent), megazol-CL Supporting information for this article is available on the WWW under https://doi.org/10.1002/cbdv.202200327 doi.org/10.1002/cbdv.202200327 64855 (protozoan infections), metronidazole (antibiotics-vaginal infections), ronidazole (antiprotozoal-histomoniasis and swine dysentery), satranidazole (antibiotic), benznidazole (antiparasitic-Chagas disease), fexinidazole (African trypanosomiasis-Trypanosoma brucei gambiense), misonidazole (radiosensitizer), and azathioprine (immunosuppressive drug-rheumatoid arthritis).…”

“…They are also found in a wide‐range of applications in coordination and materials chemistry [1–4] . Five‐membered heterocycles, like imidazole, are commonly observed in pharmaceuticals and natural products, which show antifungal, antitumor, antibacterial, and anti‐inflammatory activity [5–7] . More specifically, a plethora of pharmaceuticals contains N ‐phenylimidazole moieties [8,9] .…”