Visible-Light Induced Photoredox Catalyzed Tertiary Amine Sp~3C-H Functionalization

Being an important kind of green renewable energy, solar energy is an inexhaustible resource in nature. As society has become increasingly conscious of the adverse impacts of human industry on the environment, the development of methods to efficiently harness the energy of solar radiation has emerged as one of the central scientific challenges of the twentyfirst century. In the early of 20th century, photochemists had already realized that the sun might represent an clean and renewable energy to initiate organic transformation. Giacomo Ciamician, in 1912, speculated a bright future about utiliting solar energy in modern chemistry industry. However, organic molecules generally cannot absorb visible-light efficiently, thereby, visiblelight-induced organic reactions was not popular until recently. In the past several years, the utility of visible light to drive organic transformations witnessed rapid development and attracted considerable attention in both academia and industry. Various chemical reactions promoted by irradiation with visible light have been elegantly devised and developed into practical synthetic methods. Among of them, the oxidation of C(sp3)-H bonds adjacent to nitrogen atoms has been widely developed. The C(sp3)-H bonds are universal in organic compounds, and the functionalization of a C(sp3)-H bond to form a new C-C bond with various transition-metals provides a potent strategy to access numerous complex molecules. The development of a mild and effective method to activate a C(sp3)-H bond with clean and renewable energy is of high interest. The visible-light mediated C(sp3)-H bond functionalization has draw great attention because of the feature of mild conditions, energy-saving and environmentally benign. In this dissertation, visibel light induced photoredox catalyzed sp3C-H functionalization reactions were investigated. Four parts are included in this dissertation:Part ?:we have developed an effective method to synthesize C1-difluoromethylated N-aryltetrahydroisoquinolines by means of visible-light photoredox catalysis using a, a-difluorinated gem-diol as difluoromethylene reagent under mild conditions. This protocol was fairly feasible and easy-to-handle, and inexpensive reagent CCl4 was used here as the sacrificed oxidant.Part ?:A photoredox catalyzed monofluoromethylation of tetrahydroisoquinolines with a-fluorinated gem-diols has been developed. This protocol provides a new method to introduce CF group with stable, easily-prepared monofluorinated gem-diol as CF source. A mechanistic investigation is present based on control experiments.Part ?:we have developed a visible light photoredox catalyzed radical-radical coupling reaction to construct 4-,5-, and 6-membered N-heterocycles. Ketyl and a-amino radical were formed in one catalytic cycle via proton-coupled electron transfer without extra sacrificial electron donor.Part ?:An efficient intramolecular addition of a-aminoalkyl radicals to Machel-acceptors was achieved by visible-light induced photoredox catalysis. Cyclic y-aminobutyric acid scaffolds were synthesized via this strategy.