US 12,077,514 B2
Method for racemisation of (5R)-4-[5-(3,5-dichlorophenyl)-5-(trifluoromethyl)-4H¬isoxazol-3-yl]-2-methyl-benzoic acid
Harald Schmitt, Mainz (DE)
Assigned to Intervet Inc., Rahway, NJ (US)
Appl. No. 17/414,214
Filed by Intervet Inc., Madison, NJ (US)
PCT Filed Dec. 20, 2019, PCT No. PCT/EP2019/086634
§ 371(c)(1), (2) Date Jun. 15, 2021,
PCT Pub. No. WO2020/127944, PCT Pub. Date Jun. 25, 2020.
Claims priority of application No. 18215357 (EP), filed on Dec. 21, 2018.
Prior Publication US 2022/0041564 A1, Feb. 10, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. C07D 261/04 (2006.01); C07B 55/00 (2006.01)
CPC C07D 261/04 (2013.01) [C07B 55/00 (2013.01)] 8 Claims
 
1. A Method for racemizing a mixture containing (5R)-4-[5-(3,5-dichlorophenyl)-5-(trifluoromethyl)-4H-isoxazol-3-yl]-2-methyl-benzoic acid according to Formula (1a) and (5S)-4-[5-(3,5-dichlorophenyl)-5-(trifluoromethyl)-4H-isoxazol-3-yl]-2-methyl-benzoic acid according to Formula (1b)

OG Complex Work Unit Chemistry
wherein the mixture has an enantiomeric excess of the compound according to Formula (1a) comprising the step of:
(i) reacting the mixture with an alkaline compound in an organic solvent obtaining a reacted mixture
wherein step (i) is carried out in the absence of phase transfer catalysts and wherein the organic solvent is 2 propanol and wherein the alkaline compound is potassium hydroxide, cesium hydroxide or potassium tert-butanolate.