Electroreductive heterocyclization of ortho-piperidino substituted nitro(het)arenes

Iodine(III)-Catalyzed Oxidative Cyclization of Aryl Amines to Construct N-Alkylbenzimidazoles

“…The general procedure was followed using 40.3 mg of 3-amino-4-(piperidin-1-yl)benzonitrile (0.200 mmol), 0.063 μL of iodobenzene (0.001 mmol), 40 μL of trifluoroacetic acid (0.52 mmol), and 184 mg of selectfluor (0.52 mmol) in 4 mL of MeCN (0.05 M) for 16 h. Purification using MPLC (2:98 MeOH:CH 2 Cl 2 ) afforded 16j as a white solid (14.8 mg, 38%). The spectral data matched that reported by Begunov and co-workers: mp = 174–175 °C; 1 H NMR (500 MHz, CDCl 3 ) δ 7.94 (s, 1H), 7.43 (d, J = 8.1 Hz, 1H), 7.32 (d, J = 8.2 Hz, 1H), 4.13–4.07 (m, 2H), 3.09 (dd, J = 7.9, 4.7 Hz, 2H), 2.17–2.10 (m, 2H), 2.04 (dt, J = 9.7, 4.3 Hz, 2H); 13 C{ 1 H} NMR (125 MHz, CDCl 3 ) δ 154.5 (C), 142.5 (C), 137.4 (C), 125.3 (CH), 123.7 (CH), 120.1 (C), 109.8 (CH), 105.2 (C), 42.8 (CH 2 ), 25.5 (CH 2 ), 22.4 (CH 2 ), 20.4 (CH 2 ); ATIR (thin film) 2949, 2884, 2358, 2342, 2218, 1613 cm –1 .…”

Nitroarenes and nitroalkenes as potential amino sources for the synthesis of N-heterocycles

“…Electrochemical reduction of ortho piperidino substituted nitro(het)arenes for the synthesis of benzimidazoles under undivided cell conditions was published in the same year. 60…”

Recent Advances to Mediate Reductive Processes of Nitroarenes Using Single-Electron Transfer, Organomagnesium, or Organozinc Reagents

“…Electrochemical reduction of 2-piperidine-nitroarenes 171 was reported by Begunov and co-workers to afford benzimidazoles 172 (Scheme 26 ). 86 While chemical reduction using tin or titanium reductants are established, the authors wrote that they were motivated to replace them with electricity to simplify the isolation of the N -heterocyclic product and to reduce the waste generated in the process. The authors discovered that the desired transformation could be accomplished best using a lead cathode and a graphite plate anode.…”