Rh(Ⅲ)Catalyzed C-H Functionalization And Indoles Synthesis

Transition-metal catalyzed C-H bond activation provides an atom-and step-economical approach for organic synthesis. A variety of transition metals (Pd, Ru, Ir, etc.) catalyzed C-H activation functionalization reaction have been developed. In the past five years, Rh (Ⅲ) catalyzed C-H activation reactions have been fully developed, and provides an effective method for the synthesis of biologically active compounds. This paper first reviews the Rh(III) catalyzed C-H activation functionalization reactions and application in the synthesis of heterocyclic. Notwithstanding these pioneering examples, further development of Rh(III) catalyzed C-H activation reactions reactions is needed in synthetic organic chemistry.1. Rhodium-Catalyzed C-H Activation/Olefination of Phenol Carbamates. We reported a practical protocol for ortho C-H activation/olefination of phenol carbamates. The reaction tolerates a variety of important functional groups (aryl-Br, aryl-Cl) and many different olefins can be used in this process. This reaction exhibits different reactivity as compared to the Pd-catalyzed processes, this method provide a new approach for the synthesis of ortho-substituted phenols.2. Rh-catalyzed C-H bond activation with allenes to produce highly unsaturated conjugated olefins. Rh(Ⅲ) catalyzed C-H bond activation with allenes to produce unsaturated conjuncted olefins was reported. The reaction is applicable to both olefin and arene C(Sp2)-H, compatible with varieties of functional groups. The obtained products can be transformed into other important skeletons.3. Rhodium-catalyzed Directed C-H Cyanation. We report the first example of Rh-catalyzed directed C-H cyanation. N-Cyano-N-phenyl-p-methylbenzenesulfonamide (NCTS), a user-friendly cyanation reagent, was used in the transformation. Many different directing groups can be used in this cyanation process and the reaction tolerates a variety of important functional groups (aryl-Br, aryl-I unprotected phenol, epoxide), A number of heteroaromatic nitriles were successfully synthesized by using this method, the reaction may provide a practical tool for rapid derivatization of bioactive compounds.4. A practical Rh-catalyzed reaction was developed to achieve2-alkyl-substituted indoles synthesis. The reaction can tolerate a variety of synthetically important functional groups (aryl-Br, aryl-I, heterocycle). The indole products can also be transformed into other important skeletons. Two bioactive compounds, i.e. indomethacin and pravadoline were prepared using the new method.