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With sodium hydroxide; In acetonitrile; at 20℃; for 2h;
General procedure: A mixture of (E)-4-phenylbut-3-en-2-one (1e) (146 mg, 1.0 mmol) and TsNHNH2 (205 mg, 1.1 mmol) in CH3CN (2 mL) were stirred at room temperature for 3 h and then CH3CN (2 mL), NaOH (44 mg, 1.1 mmol) were added and the mixture was heated at reflux for 17 h, then NaOH (60 mg, 1.5 mmol) and benzyl bromide (255 mg, 1.5 mmol) were subsequently added and the mixture was stirred at room temperature for 2 h. The product was extracted with Et2O and the organic layer was washed with brine, dried over anhydrous MgSO4, filtered, and concentrated in vacuo. Purification by chromatography on silica gel afforded the desired product 4s as white crystalline solid (194 mg, 78% yield).
With bromine; In dichloromethane; at 0 - 20℃; for 2.5h;
To a solution of 5-methyl-3-phenyl-lH-pyrazole (8.0 g, 50.6 mmol) in dichloromethane(150 mL) was added bromine (8.08 g, 50.6 mmol) dropwise at 0 0C. The reaction was stirred at that temperature for 30 min and continued at room temperature for 2 h. After the reaction was quenched with an aqueous solution OfNa2SO3 (10% w/w, 10 mL), the organic solvent was removed and the aqueous mixture was extracted with EtOAc, washed with brine, dried over MgSO4, and concentrated. The residue was purified by silica gel column chromatography to give the title compound as a yellow oil (9.5 g). LCMS mlz = 236.9 (M+H4). 1H NMR (400 MHz, DMSO-J6) delta ppm 2.26 (s, 3H), 7.30-7.57 (m, 5H), 13.12 (s, IH).
4,4-dimethyl-2,2-dioxo-2λ'-[1,2,3] oxathiazinane-3-carboxylic acid tert-butyl ester[ No CAS ]
[ 865-47-4 ]
[ 3347-62-4 ]
[ 93-91-4 ]
[ 521267-14-1 ]
Yield
Reaction Conditions
Operation in experiment
With hydrogenchloride; hydrazine; In dichloromethane; N,N-dimethyl-formamide; acetonitrile;
Step C]: [1,1-Dimethyl-3-(5-methyl-3-phenyl-pyrazol-1-yl)-propyl]-carbamic Acid Tert-Butyl Ester 5-Methyl-3-phenyl-1H-pyrazole (320 mg, prepared from benzoylacetone and hydrazine according to Ali et al., Pak. J. Sci. Ind. Res. 1993, 36 (12), 502) was dissolved in DMF (7 ml) and cooled to 0 C. with an ice bath. Potassium-tert-butoxide (284 mg) was added in portions and the mixture was stirred for 45 min at 0 C. Then, 4,4-dimethyl-2,2-dioxo-2lambda'-[1,2,3]oxathiazinane-3-carboxylic acid tert-butyl ester (617 mg) was added in one portion and the reaction mixture was allowed to stir for 20 hours at RT. HCl (1N aqueous solution, 10 ml) was added and stirring was continued for 15 minutes. The mixture was diluted with ether, washed with water and brine (the aqueous layers were re-extracted twice with ether), dried and evaporated. The crude product was purified by flash chromatography (0 to 15% gradient of CH3CN in CH2Cl2) to give the desired product as a yellow gum. Yield: 545 mg. A regioisomer present in minor amounts was removed in the chromatographic purification step. MS (ISP): 344.5 (MH+)
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