p-Toluenesulfonic acid → HCID 131710398, compound

Participants

Reaction Steps

Meanwhile, 4-methylpentan-2-one (70 ml) was stirred and cooled to 0° and ethyl chloroformate (2.0 ml, 0.0208 mole) and a 1% solution of N-methylmorpholine in 4-methylpentan-2-one (3 ml) were added. The solution was cooled to -5° and sodium (R)-N-(1-methoxycarbonylpropen-2-yl)-α-aminophenylacetate (5.42 g, 0.02 mole) was added. The suspension was stirred at 0° to -5° for 30 minutes and then cooled to -30°. The 6-APA solution prepared above was added so as to keep the temperature of the mixture between -25 and -30°. The mixture was stirred for 30 minutes at -30° when water (50 ml) was added. Aqueous 2.53 M toluene-p-sulphonic acid monohydrate solution (17 ml, 0.043 mole) together with 10 M aqueous sodium hydroxide solution (ca. 0.1 ml) were added to the stirred two-phase mixture to adjust the pH to and maintain it at 1.5. The mixture was stirred at 5° for 1 hour when more toluene-p-sulphonic acid solution was added to readjust the pH from 2.5 to 1.6. The resulting suspension was stirred for a further 2 hours at 5° and filtered. The wet cake was washed with 4-methylpentan-2-one (50 ml), sucked as dry as possible and washed by slurrying with ice-cold water (50 ml). The solid was refiltered, washed with ethyl acetate (20 ml) and dried in vacuo at 45° to give ampicillin toluene-p-sulphonate (8.51 g, 81.7% th.), [α]D25 + 173° (c 0.97; 0.2 M pH 7 phosphate buffer). We claim:

Provenance & Evidence