Indium-catalyzed Oxidative Cross-dehydrogenative Coupling

With the emergence of the concepts of atom economy and green chemistry, research of forming new C-C bond via directly C-H activation has become a hotspot. As one of the new methods for C-C bond formation, Cross Dehydrogenative Coupling(CDC), having many advantages such as simple operation, mild condition, cheap materials and high atom economy, has attracted more and more attention recent years.In Cross Dehydrogenative Coupling, the oxidants and metal additives can effectively promote the cross-dehydrogenative coupling reaction of 2H-chromenes with dicarbonyl compounds and aromatic ring compounds via C-H bond activation. The alkylation and arylation of 2H-chromenes can directly generate the corresponding products with high yield, which is proved to be of high value. Moreover, due to the chemical properties of oxidants and metal additives, the direct oxidative Cross Dehydrogenative Coupling(CDC) with readily available C-H components provides excellent opportunities to synthesize the target with minimal amount of steps and less by-products. so the research on the coupling reaction system of catalytic oxidation has more realistic significance. This thesis mainly studied and demonstrated this new method, and the specific contents are as follows:Initially, we established the direction of study after reading a large amount of literature. The oxidative CDC of 2H-chromene with diisopropyl malonate was selected as the model reaction for optimization, and the researeh mainly contains four fields as follows: type of metal additive, amount of additive, type of oxidation agent and type of solvent. Then we got the optimized conditions: DDQ(1 equivalent) and In(OTf)3(0.1 equivalent) in DCE.With the optimized oxidative cross-coupling conditions in hand, the nucleophilic scope of the transformation was studied. A variety of dicarbonyl compounds as well as aryl rings were accommodated by the reaction conditions. The substituent effect of 2H-chroman on the coupling reaction was subsequently explored. At last, We proposed a plausible mechanism for the indium-catalyzed oxidative CDC of chromenes after the completion of the experiment.