Studies On Lewis Acid-catalyzed C-H Functionalization To Formation Oxindoles Structure Motif

In the past decade, transition metal catalyzed C-H bond activation reactions have emerged as promising new catalytic transformations. Environmentally friendly, mild C-H bond activation reaction will became the ideal means to build a C-X bond (X=C, N, O, etc.), which is most atom economy, simplely and efficiently method for synthesis of organic molecules. Undoubtedly, this will be the most competitive research fields of catalytic chemistry in the next two decades. Thus, in-depth study of the basic law of the C-H bond activation and cleavage, not only has the important academic significance, but also has a huge potential practical value. Scientific American magazine has been published a C-H bond activation specifically comment and considered it as the "holy grail" of organometallic chemistry.During my PhD, I had the great honor involved in the research groups of Professor Shang-Dong Yang and Professor Yong-Min Liang to study on new methods of lewis acid-catalyzed direct conversion of aromatic rings carbons hydrogen bonds into carbon-carbon bonds to form oxindoles structure motif.This thesis includes the following:In first chapter, recent studies about transition-metal-catalyzed reaction of diazo compounds generates metal carbene or carbenoid intermediates that undergo catalytic C-H bond insertion reactions and their application of total synthesis are reviewed.In second chapter, A novel protocol for the preparation of various oxindoles via a silver-catalyzed carbene insertion to aromatic C-H bond has been developed. The process is simple, environmentally conscious, and avoids the use of bases, oxidants, or other additives. All analyses including NMR, single crystal X-ray, and DFT calculations show that the3-methyleneoxindole is obtained as a single product. In addition experiments and computational analysis illustrated that silver prompt the formation of a free carbene and the rate-determining step of the catalytic cycle is N2dissociation.In third chapter, recent developments of transition metal catalyzed direct nucleophilic addition of C-H bonds in hydrocarbons and their derivatives to the unsaturated carbon-heteroatom to produce addition product are reviewed.In four chapter, A novel method for Sc(OTf)3-catalyzed intramolecular Friedel-Crafts alkylation to construct3-hydroxy-2-oxindoles by direct C-H addition to a-ketoanilides has been developed. In comparision with traditional methods of nucleophilic conjugate additions of organometallic reagents or electron-rich reagents to isatins and intramolecular addition of aryl chlorides to ketoamides. This protocol is simple, environmentally conscious, and omits the complicated preparation of organometallic reagents or halogenations procedures.