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Author: search.filters.author.Purahong, Nitchakan

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    DBU-Mediated Reaction of 3-Chlorooxindole and 9-Xanthyl Fluorene for Synthesis of 3-Arylidene Oxindole
    (2025-04-01)
    Purahong, Nitchakan
    ;
    Teerawatananond, Thapong
    ;
    Chotsaeng, Nawasit
    ;
    Janthakit, Pattarapapa
    ;
    Nalaoh, Phattananawee
    This work reports a new route for the synthesis of 3-(9H-fluoren-9-ylidene)indolin-2-one derivatives via the reaction of 3-chlorooxindoles and O-ethyl S-(9H-fluoren-9-yl) carbonodithioates mediated by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The reactions readily proceeded at room temperature, enable a collection of 3-alkenyl oxindoles to be prepared within a short reaction time (15 minutes). The 3-alkenyl oxindoles can be easily converted to 3-fluorenyl oxindoles by NaBH<inf>4</inf> reduction.
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    Electrochemically driven reductive cyclization of o-nitroanilines: synthesis of 1,2-fused benzimidazoles and benzo[d]imidazoles
    (2025-03-31)
    Saetan, Jutamart
    ;
    Purahong, Nitchakan
    ;
    La-Ongthong, Kannika
    ;
    Hassa, Nattawoot
    ;
    Chotsaeng, Nawasit
    The electrochemical synthesis of 1,2-fused benzimidazoles and benzo[d]imidazoles from o-nitroanilines in an undivided cell under constant current conditions was developed. The electrosynthesis proceeded through a tandem process involving nitro reduction/C(sp<sup>3</sup>)-H amination/condensation. The method can accommodate a broad range of o-nitroanilines and results in the desired products in yields of up to 99%. A plausible reaction mechanism was proposed on the basis of controlled experiments and cyclic voltammetry (CV) analysis. The benefits of the developed method include one-pot synthesis, open-air conditions, gram-scale synthesis and no requirement for a strong reductant.
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    DBU-Mediated Dimerization: Facile Access to 9,9′-Bifluorenylidenes and Isoindigos
    (2023-11-14)
    Purahong, Nitchakan
    ;
    Hongthong, Sakchai
    ;
    Chotsaeng, Nawasit
    ;
    Kuhakarn, Chutima
    ;
    Meesin, Jatuporn
    The present work describes the 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-promoted self-dimerization of 9-chlorofluorenes and 3-chlorooxindoles for the preparation of the corresponding 9,9 -bifluorenylidene and isoindigo derivatives in moderate to good yields of 29 97%. The reactions proceed readily in a short reaction time under mild and metal-free conditions. Scale-up syntheses (5.0 mmol) of selected 9,9 -bifluorenylidene derivatives proceed in decent yields, highlighting the synthetic utility of the reported protocol.