Carbon Dioxide → HCID 51064101, compound

Participants

Reaction Steps

182 g of (R)-2-(p-hydroxyphenoxy)-propionic acid 100% (1 mol) in 1500 g of acetonitrile 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. Then, 193 g of potassium carbonate powder (1.4 mols) and 2 g of tetrabutyl ammonium bromide as the phase transfer catalyst are added to the reaction mixture, and at a temperature of 70 to 75° C., 165 g of 5-chloro-2,3-difluoropyridine (1.1 mols) are added over the course of 30 minutes. After 8 hours, the compound of formula V thus obtained is reacted totally to form the (R)(+)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acid propinyl ester, directly, without isolation, at a temperature of 70-75° C., by measuring in chloroformic acid propargyl ester, whereby CO2 is released. Working up is effected analogously to example P1. (R)(+)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acid propinyl ester is obtained with a content of 97% (GC), corresponding to a yield of 80% of theory, based on (R)-2-(p-hydroxyphenoxy)-propionic acid.

Provenance & Evidence