At the same time, in my other blogs, there are other synthetic methods of this type of compound, Ethyl 1,5-dimethyl-1H-pyrazole-3-carboxylate, and friends who are interested can also refer to it.
As we all know, there are many different methods for the synthesis of a compound, and people can choose the synthesis method that suits their own laboratory according to the actual situation. 5744-51-4 name is Ethyl 1,5-dimethyl-1H-pyrazole-3-carboxylate, This compound is widely used in many fields, so it is necessary to find a new synthetic route. The downstream synthesis method of this compound is introduced below. 5744-51-4
Ethyl 5-methyl-1-hydro-pyrazolecarboxylate (30.8 g, 200 mmol) was dissolved in 200 mL of dry tetrahydrofuran solution. Sodium hydride (4.8 g, 200 mmol) was slowly added under ice-cooling and sodium hydride was added completely. After the temperature was raised to 50C, the mixture was stirred for 1 hour and cooled to room temperature. Methyl iodide (28.2 g, 200 mmol) was then dissolved in 100 mL of tetrahydrofuran and slowly added dropwise to the reaction. The addition was complete and heating to 50C was continued for 2 hours. After the reaction is complete, cool to room temperature, remove tetrahydrofuran under reduced pressure, then add 100 mL of water, extract with ethyl acetate (100 mL x 3), combine the organic layers, dry, and remove the ethyl acetate under reduced pressure to give 5-methyl-1-carbonitrile. Ethyl 2-pyrazolecarboxylate 26.6 g, 85%.Lithium aluminum hydride (3.8 g, 100 mmol) was added to a dry three-necked flask, 200 mL of dry tetrahydrofuran, and then ethyl 5-methyl-1-methyl-pyrazolecarboxylate (16.8 g, 100 mmol) was dissolved in 100 mL of dry. Tetrahydrofuran was slowly added dropwise to the three-necked flask, and stirring was continued for 4 hours after completion of the addition. After the reduction is completed, absolute ethanol is added dropwise to remove the remaining lithium tetrahydroaluminum, the tetrahydrofuran is removed under reduced pressure, 500 mL of methanol is added, the pH is adjusted to neutral, the mixture is heated to reflux for 6 hours, and the filtrate is filtrated. The filtrate is concentrated and dissolved in 100 mL of dichloromethane. And washed twice with 50 mL of saturated aqueous sodium chloride, and the organic layer was dried and concentrated to give 5-methyl-1-methyl-pyrazolemethanol 8.8 g, 70%.5-methyl-1-carbonitrileThe base-pyrazole methanol (6.3 g, 50 mmol) was dissolved in 20 mL of methylene chloride. Thionyl chloride (6 g, 50 mmol) was slowly added dropwise. After the addition was complete, stirring was continued for 2 hours. After the reaction was complete, saturated sodium bicarbonate was added slowly. The aqueous solution was adjusted to pH neutral and then extracted with 200 mL of dichloromethane. The organic layers were combined, dried and concentrated to give 3-chloromethyl-1-methyl-5-methylpyrazole (6.5 g, 90%).In a 50 mL round bottom flask was added 3-chloromethyl-1-methyl-5-methylpyrazole (1.44 g, 10 mmol) and N-(2,4,6-trimethylphenyl)imidazole (1.86 g) (10 mmol), 20 mL of acetonitrile, and the mixture was heated under reflux for 6 hours, cooled to room temperature, and the solvent was distilled off under reduced pressure. The obtained solid was dissolved in water and filtered. The filtrate was saturated with aqueous solution of ammonium hexafluorophosphate, and the solid precipitated and was dried to give 3.8. g imidazolium salt ligand (HL1PF6), yield 88%.
At the same time, in my other blogs, there are other synthetic methods of this type of compound, Ethyl 1,5-dimethyl-1H-pyrazole-3-carboxylate, and friends who are interested can also refer to it.