Method for the preparation of cinacalcet and intermediates and impurities thereof
A method for the preparation of Cinacalcet is disclosed comprising treating (R)-1-naphthyl ethylamine with an aromatic aldehyde to form (1R)-1-(2-naphthyl)-N-(aryl methylene)ethanamine derivative of Formula (IV), which is further treated with 1-(3-halopropyl)-3-(trifluoromethyl)benzene of Formula (V) to obtain an iminium salt of Formula (VI), followed by hydrolysis to obtain Cinacalcet free base.
1. A method of preparing a compound of Formula (I) or a salt thereof, comprising reacting a compound of Formula (IV) with a compound of Formula (V) to produce the compound of Formula (I),
wherein
Ar is benzyl-, phenyl- or naphthyl-, which may be mono- or di- or poly substituted with alkyl, aryl, alkoxy, amino, hydroxyl, halogen, and nitro groups, and X is chloro, bromo, or iodo.
2. The method of claim 1 , wherein
(a) the reaction of the compound of Formula (IV) with the compound of Formula (V) (1-(3-halopropyl)-3-(trifluoromethyl)benzene) forms an iminium salt of Formula (VI):
and
(b) the iminium salt of Formula (VI) is treated with water and/or acid solution to obtain the compound of Formula (I):
3. The method of claim 1 , wherein the compound of Formula (IV) and the compound of Formula (V) are reacted at a temperature of 80 to 180° C.
4. The method of claim 3 , wherein the reaction is carried out in the presence of a solvent.
5. The method of claim 4 , wherein the solvent is selected from an organic solvent, an inorganic solvent, or mixtures thereof.
6. The method of claim 4 , wherein the reaction is carried out at a reflux temperature of the solvent.
7. The method of claim 5 , wherein the organic solvent is selected from C2-C8 aliphatic amides, cyclic amides, dimethylsulfoxides, hydrocarbon solvents, alcoholic solvents, ether solvents, and mixtures thereof.
8. The method of claim 7 , wherein the C2-C8 aliphatic amide is selected from N,N-dimethylacetamide, dimethylformamide, hexamethylphosphoramide, and the like.
9. The method of claim 7 , wherein the cyclic amide is selected from 1,3-dimethyl-2-imidazolidinone (DMI), N-methyl-2-pyrrolidinone (NMP), and the like.
10. The method of claim 7 , wherein the hydrocarbon solvents are selected from toluene, xylene, and the like.
11. The method of claim 7 , wherein the alcoholic solvents are selected from methanol, ethanol, propanol, butanol, and the like.
12. The method of claim 7 , wherein the ether solvent is diglymes.
13. The method of claim 7 , wherein the organic solvent is N-methyl-2-pyrolidnone.
14. The method of claim 5 , wherein the inorganic solvent comprises an ionic liquid selected from 1-ethyl-3-methyl imidazolium ethylsulfate, [hmim]BF 4 , [hbim]Br, [hbim]Cl, [hbim]BF 4 , [hbim]PF 6 , [bbim]Br, [bbim]Cl, [bbim]ClO 4 , [bbim]BF 4 , [bmim]PF 6 , [bmim]BF 4 , and the like, and mixtures thereof.
15. The method of claim 2 , further comprising the addition of a catalyst.
16. The method of claim 15 , wherein the catalyst is selected from potassium iodide (KI), sodium iodide (NaI), or phase transfer catalysts selected from n-benzylcinchonidinium chloride, benzyltributylammonium chloride, 3-ethyl-5-(2-hydroxyethyl)-4-methylthiazolium bromide, phenyltrimethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, tricaprylmethylammonium chloride, tetrabutylammonium iodide, and the like, or combinations thereof.
17. The method of claim 3 , wherein the reaction is carried out at a temperature of 120 to 150° C.
18. The method of claim 2 , wherein the compound of Formula (V) is selected from 1-(3-chloropropyl)-3-(trifluormethyl)benzene, 1-(3-bromopropyl)-3-(trifluormethyl)benzene, or 1-(3-iodopropyl)-3-(trifluoromethyl)benzene.
19. The method of claim 2 , wherein the acid solution comprises concentrated hydrochloric acid.