Rhodium(â…¢)-Catalyzed C-H Ctivation Of Arenes And Copper-, Iron-Catalyzed Ifunctionalization Of Alkenes

Transition-metal-catalyzed C-H bond functionalization has emerged rapidly as an efficient and straightforward synthetic protocol employed in the synthesis of complex natural products or functional molecules over the past few years. Recently, increased attention has been focused on rhodium(â…¢)-catalyzed C-H bond activation reaction owing to its high catalytic efficiency, broad substrate scope and excellent functional group tolerance.In addition, transition-metal-catalyzed difunctionalization of alkenes is also a hot topic in recent synthetic organic synthesis. This dissertation mainly focused on the studies of rhodium(â…¢)-catalyzed C-H activation reaction as well as iron-and copper-catalyzed difunctionalization of alkenes. The main research details are as follows:1. A versatile rhodium(â…¢)-catalyzed C-H bond activation and further direct arylation of (hetero)arenes with arylsilanes in aqueous media is developed. This transformation exhibits excellent reactivity, broad substrate scopes. Various functional groups are well tolerated under the mild reaction conditions which provides the corresponding coupling products in excellent yields. In addition, the rhodium(â…¢)-catalyzed C-H bond activation and further benzylation and allylation of (hetero)arenes with organosilanes in THF is also developed. The benzylation reaction also shows excellent reactivity and broad substrate scopes. However, the allylation reaction shows narrow substrate scopes and only moderate yields were obtained. Intermolecular competition experiments for the kinetic isotopic effect were also carried out and a plausible mechanism was proposed to account for this transformation.2. The iron-catalyzed cascade carbodi-and trichloromethylation of activated alkenes by taking advantage of readily available dichloromethane and tetrachloromethane as the chloromethyl sources is developed. A diaryliodonium salt is used as the efficient oxidant which triggers the formation of chloromethyl radicals in this transformation. Radical-trapping experiments reveal that chloromethyl radicals are probably involved in this process. This protocol tolerates a wide range of synthetically relevant functional groups and enabled the efficient synthesis of biologically active chloromethyl-containing oxindoles in good to excellent yields.3. A novel and efficient copper-catalyzed vicinal oxyazidation and diazidation of alkenes by taking advantage of the azidoiodine(â…¢) reagent as the azide source under mild reaction conditions is developed. This reaction tolerates a wide range of functional groups and allows the convenient synthesis of functionalized alkyl azides in good to excellent yields. In addition, we applied this novel copper-catalyzed vicinal oxyazidation and diazidation to the late-stage modification of biologically relevant complex molecules. The synthetic potential of this protocol in organic synthesis was further demonstrated by a variety of synthetically useful transformations.