Studies Of Allyl Nucleophilic Substitution Reaction Catalyzed By N-heterocyclic Carbenes And Metal Complexes

Cooperative catalysis include two or more catalysis have attracted great attention of chemists, because of its many characteristics, such as efficient, economic, green and simple operation. It is widely applied in the design and synthesis of new drug, synthesis of natural product and combinatorial chemistry. Having the advantages of metal and organic catalyst, Metal-organic cooperative catalysis becomes a hot research area in organic synthesis.In this paper, a continuous reaction catalyzed by N-heterocyclic carbenes and Ni/Pd cooperative catalysis was studied. The continuous reaction includes benzoin condensation and allylic nucleophilic substitution. Allylated α-hydroxy carbonyl compound was prepared and characterized.(1) With the presence of nickel(Ⅱ)/Palladium(Ⅱ) chloride as metal complex catalyst and N-heterocyclic carbene as organic catalyst effective one pot synthesis of allylated α-hydroxy carbonyl compound was developed using benzaldehyde and cinnamyl acetate as precursors in potassium carbonate THF solution.(2) With the presence of Palladium(Ⅱ) chloride as metal complex catalyst synthesis of allylated α-hydroxy carbonyl compound was developed using α-hydroxy ester compound and cinnamyl acetate as precursors in potassium carbonate THF solution. Experimental results show that α-hydroxy ester type compound can also be used as nucleophile to participate allyl nucleophilic substitution reaction.(3) In microwave-assisted, nucleophilic substitution reaction catalyzed by N-heterocyclic carbene and metal complexes cooperative catalysis was further studied. Compared with traditional methods of heating oil bath, Microwave Technology shortens the reaction time from 18 h to 100 min, yield from 70 % to 85 %.