Phosgene → tert-Butyl 2-methyl-2-[3-(4-methylsulfanyl-3-trifluoromethylphenyl)ureido]propionate

Participants

Reaction Conditions

Reaction Steps

Compound 114.1 can be prepared by process “A”. To this end, 1.04 g of 4-methylsulfanyl-3-trifluoromethylphenylamine were dissolved in 25 ml of dry acetonitrile. This solution was added dropwise with stirring to a 20% solution, heated to 70° C., of phosgene in toluene, and then stirred at 80° C. for 2 h. The cooled reaction solution was concentrated under reduced pressure, and the residue was taken up with toluene and concentrated again under reduced pressure. Finally, the residue was dissolved in 25 ml of dry tetrahydrofuran and the solution was admixed with stirring with 0.88 g of tert-butyl 2-amino-2-methylpropionate hydrochloride. 1.05 ml of triethylamine were slowly added dropwise to the reaction mixture which was then stirred at room temperature for 4 h. The reaction mixture was admixed with water and extracted with ethyl acetate. The organic phase was dried over magnesium sulfate, filtered and concentrated. tert-Butyl 2-methyl-2-[3-(4-methylsulfanyl-3-trifluoromethylphenyl)ureido]propionate (molecular weight 392.13 (C17H23F3N2O3S); retention time Rt=2.40 min. [B]; MS (ESI): 337.26 (MH+−C4H8)) was obtained. The urea was dissolved in 20 ml of tetrahydrofuran, admixed with 4.9 ml of concentrated hydrochloric acid and stirred at 80° C. for 2 h. The cooled reaction mixture was concentrated under reduced pressure and the residue was admixed with ethyl acetate and water. The organic phase was removed, washed with saturated sodium hydrogen-carbonate solution and then with water, dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by chromatography on silica gel with 96/4 dichloromethane/methanol. 21.2 g (90% yield) of 5,5-dimethyl-3-(4-methylsulfanyl-3-trifluoromethylphenyl)imidazolidin-2,4-dione 114.1 were obtained. Molecular weight 318.06 (C13H13F3N2O2S); retention time Rt=1.93 min. [B]; MS (ES−): 317.07 (M−H+).

Provenance & Evidence