Study On The Synthesis Of Quinoline N-oxides Derivatives Via Transition Metal-catalyzed C-H Bond Activation

In this thesis, the synthesis of quinoline N-oxides derivatives via transition metal catalyzed C-H activation was studied. The results obtained are as follows:1. Sulfonylation of quinoline N-oxides with aryl sulfonyl chlorides via copper-catalyzed C-H bond activationAn efficient approach to the direct2-sulfonylation of quinoline N-oxides has been developed based on copper-catalyzed C-H bond activation (Scheme1). This novel method provides easy access to sulfonylated heterocyclic compounds using commercially available, inexpensive aryl sulfonyl chlorides as the sulfonylation reagents and cheap copper (10mol%of CuI) as the catalyst. Various2-aryl sulfonyl quinolines were obtained in up to91%yields in chemo-and regioselective manners. A plausible reaction mechanism was outlined according to the literature and reaction results in Scheme2. 2. Direct C2-alkylation of quinoline N-oxides with ethers via palladium-catalyzed dehydrogenative cross-coupling reaction.A novel, simple and efficient protocol for the direct C2-alkylation of quinoline N-oxides with ethers has been developed under base-free conditions (Scheme3). The dehydrogenative cross-coupling reactions of the sp3C-H bond in ethers with the sp2C-H bond in quinoline N-oxides proceeded smoothly in the presence of5mol%Pd(OAc)2as catalyst, tert-butyl hydroperoxide (TBHP) as oxidant, H2O and tetrabutylammonium bromide (TBAB) as additives, providing the corresponding products in up to96%yields. This findings offer a new, simple, and mild method for synthesizing the useful quinoline N-oxides containing molecules derivatives. This transformation features with step-and atom-economic, environmentally friendly and highly region-selective. A plausible mechanism for this reaction was depicted in Scheme4according to the literature and the results obtained.