Studies On C-H Activation/C-N Bond Formation Reactions Catalyzed By Iron Salt

C-H bond activation reactions can be used to improve the atom economy and shorten the reaction steps, it is green and economic and one of the most important research fields in organic synthesis. C-H bond activation reactions catalyzed by precious metals have been largely reported. The construction of N-heterocycles via transition-metal catalyzed C-H bond direct amination reactions remains a challenging research topic in organic synthesis. While little with C-H bond activation reactions catalyzed by inexpensive metals was reported, C-H activation/C-N bond formation reactions catalyzed by iron were even less. As an abundant, cheap, and less toxic element, iron is an ideal candidate to replace precious metals in organic synthesis, especially for practical large scale preparation. The research was a great challenging from both economic and ecological points of view.The research mainly contains three fields as follows:The first chapter is a review to summarize the C-H activation/C-N bond formation reactions catalyzed by metals. Precious (Pd, Rh, Ru) and inexpensive (Cu, Fe) metals catalyzed C-H activation/C-N bond formation reactions were mainly introduced.In the second chapter, we studied FeBr3/O2mediated C-H activation/C-N bond formation reactions using arylhydrazones as substrates. The direct intramolecular C-N bond formation reactions of various phenylhydrazones from benzophenone or α,β-unsaturated ketones were performed in toluene, using molecular oxygen as an environmentally friendly oxidant and the inexpensive and nontoxic iron(Ⅲ) as the catalyst. The reaction enriched the preparation procedures for1H-indazoles and1H-pyrazoles, and has a promising future for industrial applications.In the third chapter, we realized C-H activation/C-N bond formation reactions through multiple cross-dehydrogenative-coupling (CDC) reactions in one pot in the presence of FeCl3/tBHP. This reaction used arylamines and N-alkyl lactams as substrates to form a series of tetrahydroquinoline derivatives via intermolecular coupling and cyclization reactions. The reaction included two C-C bonds and one C-N bond formation as well as one C-N bond cleavage under very mild conditions.