Design Of New Catalysts And Their Application In Different Conditions In Baylis-Hillman Reaction

Baylis-Hillman reaction is an important reaction for carbon-carbon bond-formingin organic synthesis. The bond-forming reaction between the active alkenes (alkynes)and aromatic aldehydes provides diverse classes of densely functionalized molecules,which are generally referred to as the Baylis Hillman adducts. Now more attention hasbeen paid to the Baylis-Hillman reaction, which is a very hot topic in organicchemistry. It’s reported that a series of catalysts applied to Baylis-Hillman reaction,such as inorganic or organic base, macromolecular polymers, ionic liquids and so on.In this paper, Balis-Hillman reaction has been studied as following:Firstly, we use DABCO as major catalyst, and choose other alkalescent smallmolecule catalysts as co-catalysts, research their applied in Baylis-Hillman reaction inconditions, which is the different proportions, different solvents, different reactiontimes and so on. Interestly, the best isolated yield was obtained when the ratio ofDABCO:NMP was presented as5:2in CH2Cl2solvent, the product can be isolateyield92%. And then, with the optimum conditions in hand, the scope ofBaylis-Hillman reaction was explored by different reaction substrates. It was foundthat the better isolated yield was achieved when aldehydes with electron with-drowinggroups were used as reaction substrates in Baylis-Hillman reation.Secondly, imidazoles and tetramethyl guanidine ionic liquids were synthesized,and the acceleration of the reaction was studied using these ionic liquids as mediumin Baylis-Hillman reaction. These results show that the catalytic efficiency ofguanidines ionic liquids [MTMG]I is better than that of [BMIM]X obviously. Theisolated yield could be got as92%when the reaction between p-nitrobenalhyde andmethyl acrylate occurred in [MTMG]I ionic liquids system.Thirdly, a series of catalytic activities of liquid membrace which is formedbyionic liquid immobiled silica were designed. Initially, N-methylimidazole waslinked to the actived silica gel through3-chloropropyltrimethoxysilane, it is the liquidmembrace which is formed by ionic liquid immobiled silica, and then DABCO orTMEDA was supported on it. After this, this kind of catalysts was used inBaylis-Hillman reaction. The conclusion could be got that31.2%was the best isolatedyield when the reaction between p-nitrobenalhyde and methyl acrylate occurred incatalytic system of DABCO: modified silica gel accoding to Mass ratio of1:9. It canget product isolated yeild31.2%. Unfortunately, no catalytic effect was found for recycle using.Lastly, the effects of parameters, such as ultrasonic, solvent and so on, oncatalytic efficiency of DMAP were studied in the Baylis-Hillman reaction betweeno-nitrobenalhyde and methyl acrylate. These results indicated that the ultrasonicaccelerated Baylis-Hillman reaction significantly. The best isolated yield could beobtained as80%when the ratio of o-nitrobenalhyde and methyl acrylate was1:2andno solvent was present under DMAP catalytic system.