Carbon Dioxide → HCID 51064101, compound

Participants

Reaction Steps

182 g of (R)-2-(p-hydroxyphenoxy)-propionic acid 100% (1 mol) in 600 g of DMF are converted into the corresponding potassium salt by adding 69 g of potassium carbonate powder (0.5 mols) at 70° C. whilst cleaving the CO2. To this solution are added 193 g of potassium carbonate powder (1.4 mols) and then, at a temperature of 70-75° C., 165 g of 5-chloro-2,3-difluoropyridine (1.1 mols) are added over the course of 30 minutes. After 4 hours, the compound of formula V thus obtained is reacted totally, by measuring in 86 g of propargyl chloride (1.15 mols) as a 60-70% toluene solution over the course of 2 hours directly, without isolation, at a temperature of 70-75° C., to form the (R)(+)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acid propinyl ester. The salts are filtered off, washed with 300 g of DMF in portions, and the filtrate is concentrated to the melt on a rotary evaporator under vacuum at a temperature of 120°C. The crude melt of the (R)(+)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acid propinyl ester is mixed at a temperature of 50°C. with 300 g of ethanol/water 9:1, seeded at a temperature of 30 to 35° C. and cooled to a temperature of 0 to 50° C. The crystal pulp is added to a suction filter, washed with 70 g of ethanol/water 9:1, and dried under vacuum at a temperature of 30 °C. 307 g of active substance are obtained with a content of 97 % (GC), corresponding to a yield of 85% of theory, based on (R)-2-(p-hydroxyphenoxy)-propionic acid.

Provenance & Evidence