Phosgene → HCID 19886291, compound

2-methyl-5-nitrobenzoic acid (52 g., 0.28 mol) is added in portions to thionyl chloride (30 ml) and slowly brought to reflux and held for 8 hours. Excess thionyl chloride was removed followed by addition of isopropyl alcohol (50 ml) and heating for 2 hours. Removal of excess alcohol gave crude ester which was reduced by adding dropwise to a mixture of iron powder (200 mesh, 56 g.), ethanol (160 ml), water (37 ml) and concentrated hydrochloric acid (4 ml) at 70° C. Stirring was employed. After the addition, the reaction was refluxed for 30 minutes before filtering hot. The iron oxide cake was washed with hot ethanol and the combined ethanol extracts were evaporated. The crude product was taken up in ethyl acetate washed with aqueous sodium bicarbonate, washed with water, dried over MgSO4 and evaporated. Residual amber oil was distilled to give 1-methylethyl 5-amino-2-methylbenzoate, a clear oil, b.p. 92°-102° C./0.05 mm. This aniline (30 g.) in ethyl acetate (75 ml was added dropwise to a saturated solution of phosgene in ethyl acetate. During the addition, stirring was employed, phosgene was bubbled in continuously and the temperature allowed to rise. At the end of the addition, external heat was applied in order to attain reflux. After approximately 30 minutes, phosgene addition was stopped and ethyl acetate was removed by distillation at atmospheric pressure to approximately half volume. The remainder of the solvent was removed under reduced pressure. The residue was distilled to give 1-methylethyl 5-isocyanato-2-methylbenzoate, a clear oil, b.p. 90°-95° C./0.06 mm. Ethyl 4,4, 4-trifluoro-3-oxobutanoate (100 g.) was stirred and heated to 70° C. while ammonia gas was introduced for 30 minutes by which time 10.3 g. of ammonia had been absorbed. Addition of ammonia was stopped and the reaction was heated to 95° C. for two hours. Cooling produced two layers of liquid, the lower was removed and dried over molecular sieves overnight. After filtering, the product was distilled, b.p. 49°-58° C./15 mm (72.9 g.) of ethyl 3-amino-4,4,4-trifluoro-2-butenoate. This ethyl 3-amino-4,4,4-trifluoro-2-butenoate (31.8 g.) was added dropwise to a stirred suspension of sodium hydride (7.3 g., 60%) in dry tetrahydrofuran (275 ml) at 10° C. After the addition, the reaction mixture was cooled to -70° C. in an acetone/dry ice bath wereupon 1-methylethyl-5-isocyanato-2-methylbenzoate (38 g.) was added dropwise over 5-10 minutes, by which time the temperature had risen to -58° C. before cooling. The reaction was allowed to come slowly to ambient temperature and left overnight. Solvent was removed from the reaction under reduced pressure and the residue taken up in water (500 ml). After washing with ether, the solution was acidified with 2N hydrochloric acid. Crude product oiled out and solidified. This solid was collected in a filter, washed with water and dried. Recrystallization for isopropyl alcohol gave a white solid, m.p. 200°-202° C., 1-methylethyl 5-[3,6-dihydro-2,6-dioxo-4-(trifluoromethyl)-1(2H)-pyrimidinyl]-2-methylbenzoate, 22.6 g. A satisfactory IR NMR and CHN analysis was obtained.

1. additionDuring the addition
2. customphosgene was bubbled in continuously and the temperature
3. additionAt the end of the addition
4. temperatureexternal heat
5. temperatureto attain reflux
6. additionphosgene addition
7. customethyl acetate was removed by distillation at atmospheric pressure to approximately half volume
8. customThe remainder of the solvent was removed under reduced pressure
9. distillationThe residue was distilled

ORD record

ord-7efe9bd0a8d340bbaec866e0527717a9

Source dataset

uspto-grants-1992_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05134145