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With hydrogenchloride; potassium tert-butylate; dimethyl sulfoxide; In cyclohexane; ethyl acetate; tert-butyl alcohol;
1a. Methyl [2-(1-(4-chlorophenyl)-3-pyrazolyloxy)pyridin-3-yl]glyoxylate At 60° C., 4.7 g (42 mmol) of potassium tert-butoxide were added a little at a time to a solution of 7.4 g (38.1 mmol) of <strong>[76205-19-1]1-(4-chlorophenyl)-3-hydroxypyrazole</strong> in 15 ml of tert-butanol. The mixture was stirred at this temperature for 1 hour and the solvent was then removed under reduced pressure. The residue was dissolved in 25 ml of abs. dimethyl sulfoxide, and a solution of 8.0 g (38.1 mmol) of methyl (2-chloropyridin-3-yl)glyoxylate in 10 ml of abs. dimethyl sulfoxide was then added at such a rate that the temperature did not exceed 30° C. After 30 minutes at room temperature, 50 ml of 0.5 N HCl were added and the reaction mixture was extracted repeatedly with ethyl acetate. The combined organic phases were washed with water and dried over sodium sulfate. The solvent was subsequently removed under reduced pressure. The resulting residue was purified by silica gel column chromatography using cyclohexane/ethyl acetate (10:1) as eluant. 5.5 g (40percent) of the title compound were obtained as a clear oil.
(ortho-[1-{4-chlorophenyl}-pyrazol-3-yl-oxymethyl]-phenyl)(5,6-dihydro-[1,4,2]dioxazin-3-yl)methanone O-methyl oxime[ No CAS ]
Yield
Reaction Conditions
Operation in experiment
In N-methyl-acetamide; water;
Example 3 Synthesis of (ortho-[1-{4-chlorophenyl}-pyrazol-3-yl-oxymethyl]- phenyl)(5,6-dihydro-[1,4,2]dioxazin-3-yl)methanone O-methyl oxime A solution of 0.97 g of <strong>[76205-19-1]1-(para-chlorophenyl)-3-hydroxypyrazole</strong> in 20 ml of anhydrous dimethylformamide (DMF) was admixed with 0.13 g of sodium hydride and then stirred at 20-25 ° C. for approximately one hour. 1.34 g of the oxime from Example 2 were then added and the mixture was stirred at 60° C. for approximately three hours and then at 20-25° C. for approximately 14 hours. 300 ml of water were added and the mixture was then extracted with methyl tert-butyl ether (MTBE). The combined organic phases were washed with water and dried, and the solvent was then removed. The residue was chromatographed over silica gel (cyclohexane/ethyl acetate mixture [1:1]), giving 1.15 g of the title compound as a light-beige amorphous powder of m.p. 56-59° C. IR [cm-1]: 1546, 1502, 1480, 1464, 1358, 1093, 1054, 998, 935, 906.
13. Preparation of 1-(4-chlorophenyl)-3-hydroxypyrazole using pure oxygen with Co(II) catalysis 900 g of a 6.9percent strength solution of 1-(4-chlorophenyl)-pyrazolidin-3-one in 5percent strength potassium hydroxide solution were admixed with 600 mg of cobalt(II) acetate and oxygen was passed into the solution at room temperature via a capillary in such a manner that it was just completely absorbed. After approximately 30 min, the reaction was complete according to HPLC monitoring, the temperature having increased to 40° C. 908 g of a solution were obtained which had a 1-(4-chlorophenyl)-3-hydroxypyrazole content of 6.7percent.
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