Process for preparation of isoxazoline substituted benzamide compound
The invention relates to process for the preparation of isoxazoline-substituted benzamide compound and intermediates thereof. The invention also relates to process for the preparation of Fluralaner and intermediates thereof.
1. A process for the preparation of fluralaner, the process comprising:
(a) reacting a compound of Formula (VI) with a compound of Formula (VII),
to obtain a compound of Formula (V),
wherein M is Cs,
wherein the reaction is performed in the presence of cesium carbonate;
(b) converting the compound of Formula (V) into a compound of Formula (IV) or its reactive derivative,
wherein the reaction is performed in the presence of boron trifluoride etherate and acetic anhydride;
(c) reacting the compound of Formula (IV) or its reactive derivative with 2-Amino-N-(2,2,2-trifluoroethyl)acetamide, or salts thereof to obtain a compound of Formula (II); and
(d) reacting the compound of Formula (II) with hydroxylamine, or salts thereof to obtain fluralaner.
2. The process according to claim 1 , wherein the reaction at step (a) is performed in the presence of water, C 1 -C 4 -alcohols, 1,4-dioxane, acetonitrile, toluene, dimethyl formamide, or mixtures thereof.
3. The process according to claim 1 , wherein the reaction at step (c) is performed in the presence of a coupling reagent selected from N,N′-dicyclohexylcarbodiimide (DCC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) or N,N′-diisopropylcarbodiimide (DIC).
4. The process according to claim 1 , wherein the reactions at step (c) and step (d) are performed in the presence of a base comprises one or more of alkali metal hydroxides selected from sodium hydroxide, potassium hydroxide, and lithium hydroxide, alkali metal carbonates selected from sodium carbonate, potassium carbonate, lithium carbonate, and cesium carbonate, alkali metal bicarbonate selected from sodium bicarbonate, and potassium bicarbonate, triethylamine, pyridine, N,N-dimethyl aminopyridine, 1,8-diazabicyclo-(5.4.0)-7-undecene (DBU), 1,5-diazabicyclo(4.3.0)non-5-ene (DBN), 4-(dimethylamino)pyridine, N,N-dimethylaniline, imidazole, and tributylamine.
5. The process according to claim 1 , wherein the reaction at step (d) is performed in the presence of a solvent selected from methanol, ethanol, propanol, and butanol, benzene, toluene, xylene, hexane, heptane, cyclohexane, diethylether, 1,2-dimethoxyethane, tetrahydrofuran, 1,4-dioxane, ethyl acetate, ethyl propionate, N,N-dimethylformamide, acetonitrile, and dimethylsulfoxide.
6. The process according to claim 1 , wherein the process comprises preparation of fluralaner without isolating the compounds of Formula (IV) and (II).