Investigation On Palladium-Catalyzed Carbon-Heteroatom Bond Formation Involving Alkenes Or Alkynes In Ionic Liquids

Ionic Liquids is an environmentally friendly "green solvent" with the advantages of stability,non-flammability,adjustment,easy to recycling.It could have some special effects with metals,and making the reaction mechanism and process may be different from that in traditional organic solvents.Therefore,research on efficient conversion reactions involving ionic liquids has gradually attracted the attention of green synthetic chemists.The formation of carbon-carbon and carbon-heteroatom bonds has always been a hot spot in the field of organic synthesis.How to construct carbon-carbon and carbon-heteroatom bonds green and efficiently has always been the frontier of organic chemists’ research.The electron-deficient nature of palladium makes it easy to coordinate with unsaturated bonds to activate olefins and alkynes.Therefore,the reaction of palladium-catalyzed olefins or alkynes is one of the important methods for building carbon-carbon and carbon-heteroatom bonds.In the early stage,our research group explored the strategy of palladium-catalyzed olefins or alkynes to build carbon-carbon and carbon-heteroatom bonds with the participation of ionic liquids.Based on the previous research,this thesis further studied the reaction of palladium-catalyzed olefins or alkynes to construct carbon-heteroatom bonds,and further developed some convenient,efficient and green construction strategies of C-N,C-O and C-S bonds.The details are as follows:(1)Palladium-catalyzed amination and oxidation reaction of electron-rich olefins in ionic liquids: In ionic liquids,alkenyl ether and aromatic amine were used as raw materials,divalent palladium was used as catalyst,bipyridine was used as catalyst’s ligand,and hydrogen peroxide was used as oxidant.Through the process of aminopalladation,oxidation addition and reduction elimination,C-N and C-O bonds are constructed simultaneously to synthesize series of α-amino acid ester compound.The method not only has the advantages of high-efficiency atom economy,mild reaction conditions and environmental protection of the oxidant,but also has wider substrate adaptability than traditional organic solvents.It is suitable for both terminal alkenes and partial internal alkenes.(2)Palladium-catalyzed three-component cascade S-transfer reaction in ionic liquids:Under the condition of ionic liquids,simple and odorless sodium thiosulfate was used as the sulfur source,via NHC-Pd catalyzed three-component cascade S-transfer reaction of alkynyl oxime and aryl halide to construct 4-sulfaisoxazole derivatives.This reaction is the first example in which odorless sodium thiosulfate is used as a sulfonating reagent and an oxime to undergo a cascade cyclization/aromatic thiolation reaction under aerobic conditions.The reaction is alkali-free and ligand-free,and has the advantages of atom economy,well functional group tolerance and environmental friendliness.