Process for the synthesis of trifluorophenylacetic acids
View Patent ↗The present invention is concerned with a process for the preparation of trifluorophenylacetic acids using a Grignard reagent and an allylating agent, such as allyl bromide.
1. A process for the preparation of a compound of formula 3:
comprising contacting a compound of the formula 1:
wherein X is a halogen selected from chlorine, bromine and iodine, with a magnesium compound and an allylating agent to produce a compound of formula 2,
and reacting the compound of formula 2 with a metal catalyst and a co-oxidant to form a trifluorphenylacetic acid of formula 3.
2. A process in accordance with claim 1 wherein the compound of formula 1 is a 2,4,5-trifluorobenzene of the formula:
wherein X is a halogen selected from chlorine, bromine and iodine.
3. A process in accordance with claim 2 wherein the compound of formula 1 is 1-bromo-2,4,5-trifluorobenzene.
4. A process in accordance with claim 1 wherein the compound of formula 2 is 1-(2-propenyl)-2,4,5-trifluorobenzene.
5. A process in accordance with claim 1 wherein the compound of formula 3 is 2,4,5-trifluorophenylacetic acid.
6. A process in accordance with claim 1 whereby the allylating agent is allyl bromide.
7. A process in accordance with claim 1 wherein the metal catalyst of the reaction is ruthenium chloride.
8. A process in accordance with claim 1 wherein the co-oxidant of the reaction is sodium periodate.
9. A process in accordance with claim 1 wherein the reaction is carried out at about −20-40° C.
10. A process for the preparation of 2,4,5-trifluorophenylacetic acid of the formula III:
comprising reacting 1-bromo-2,4,5-trifluorobenzene of the formula I:
with magnesium chloride and allyl bromide to form an olefin intermediate of the formula II:
and reacting the compound of formula II with ruthenium chloride and sodium periodate to form 2,4,5-trifluorphenylacetic acid of the formula III: