Studies On Synthesis Of Diverse 2,3-Fused Indoles Via Rhodium(?)-Catalyzed C-H Activation

The fused indole motif is prevalent in a variety of pharmaceutical active compounds,natural products and pesticide products.In recent years,transition metal-catalyzed indole functionalization and intramolecular cyclization strategies have been shown to have efficient atomic utilization and short reaction steps.The advantages are increasingly favored by organic synthesis chemists.Among them,transition metal-catalyzed indole cyclization of fused ring oxime has been widely studied.Most of the reports in the literature are one-step construction of fluorene ring skeleton with alkynyl aniline compounds.The preparation method of the substrate is more complicated,so find a mehod that simple of substrate preparation and mild of catalytic reaction is necessary.The first part of the thesis summarizes the studies on the construction of transition metal-catalyzed fused indoles and the research of diazonium compounds as conjugates.The second part of the thesis describes our research content in detail,using transition metal Rh?III?to catalyze the cyclization of pre-functionalized furfural and diazonium compounds to synthesis a series of novel 2,3-fused indoles.Currently metal-catalyzed construction of terpenoid alkaloids is one of the hot spots.It was found that in the DCE system of catalyst[RhCp*?MeCN?₃]?SbF₆?₂,additive CsOAc,furfural C2-H was activated,carbonyl diazo attack released a molecule of nitrogen to form helium ions,followed by intramolecular nucleophilic addition to C=O or C=C bonds,synthesis divergent 2,3-fused indoles.When the catalyst is[RhCp*Cl₂]₂,the ligand is AgSbF₆and the additive is Cu?OAc?₂ and diazonium substrate was increased to 4 equivalents,a2,3-fused indoles would be obtained which dialkylation at the C7 position.This is because both indole C2 and C7 will be activated at the same time under this condition.The results of the reaction were explained by mechanistic experiments.Through a large number of experiments,the asymmetric diazonium compounds with a dr value greater than 20:1 in the next batch of products were screened.This reaction has the following advantages:1)Six-and seven-membered ring 2,3-fused indoles can be synthesized;2)Mild reaction conditions and environmental protection?N₂ as the by-product?,substrate functional groups are universal.