Process for manufacturing adamantane derivatives with high yield
The present invention pertains to process for the amidation of a substituted 1-bromo-adamantane comprising a step (0) of reacting a substituted adamantane with an excess of bromine to obtain a 1-bromo-adamantane and a step (i) of reacting said substituted 1-bromo-adamantane with an amide, wherein the substituted 1-bromo-adamantane is used in the form of a mixture comprising bromine as obtained in step (0), wherein in step (0) a bromine: substituted adamantane molar ratio of from [2.5:1] to less than [5:1] is employed.
1. A process for the amidation of a substituted 1-bromo-adamantane comprising: step (0), wherein a substituted adamantane is reacted with an excess of bromine, wherein the reaction temperature in step (0) is between 50 to 100° C., to obtain a 1-bromo-adamantane and step (i), wherein the substituted 1-bromo-adamantane is reacted with an amide or urea and/or derivatives thereof to produce an amidation product, wherein the substituted 1-bromo-adamantane is used in the form of a mixture with bromine as obtained in step (0), and wherein, in step (0), a bromine: substituted adamantane molar ratio of from [2.8:1] to [3.5:1] is employed.
2. The process according to claim 1 , further comprising step (ii), wherein the amidation product of step (i) is converted to a 1-aminoadamantane derivative or a pharmaceutically acceptable salt thereof.
3. The process according to claim 2 , wherein the bromine: substituted adamantane molar ratio is [3:1].
4. The process according to claim 1 , wherein the substituted 1-bromo-adamantane in the mixture is present as a complex with bromine.
5. The process according to claim 1 , wherein the substituted 1-bromo-adamantane is 1-bromo-3,5-dimethyladamantane.
6. The process according to claim 1 , wherein the substituted 1-bromo-adamantane is 1-bromo-3,5-diphenyladamantane.
7. The process according to claim 1 , wherein the amide is acetamide or formamide.
8. The process according to claim 7 , wherein a molar ratio between the substituted adamantane and formamide of from 1:3 to 1:10 is employed.
9. The process according to claim 7 , wherein substituted 1-bromo-adamantine and bromine are transferred to the formamide solution over a time period of 4 hours at a temperature ranging from 65° C. to 85° C. under constant agitation at 90 rpm to 100 rpm.
10. The process according to claim 2 , wherein step (ii) comprises acid hydrolysis of the amidation product of step (i) by employing an organic acid or an inorganic acid or a mixture of two or more organic acids, or a mixture of two or more inorganic acids or a mixture of at least one organic acid and at least one inorganic acid.
11. The process according to claim 10 , wherein the organic acid is selected from the group of para-toluenesulphonic acid, methanesulfonic acid, para-bromophenylsulphonic acid, carbonic acid, succinic acid, benzoic acid, maleic acid, tartaric acid, fumaric acid, methylsufonic acid, formic acid, citric acid, acetic acid, oxalic acid and mixtures thereof and wherein the inorganic acid is selected from the group of hydrochloric acid, nitric acid, hydrobromic acid, sulfuric acid, phosphoric acid, nitric acid, hydroiodic acid and mixtures thereof.
12. The process according to claim 2 , wherein the 1-aminoadamantane derivative is selected from the group of memantine, amantadine, 1-Amino-methyladamantane, 1-Amino-3,5,7-trimethylada-mantane, 1-Amino-3-ethyl-5-methyladamantane and 1-Amino-3-phenyladamantane, 1-Amino-3,5-dimethyladamantane, 1-Amino-3-ethyl-adamantane, 1-Amino-3-isopropyladamantane, 1-Amino-3-n-butyl-adamantane, 1-Amino-3,5-diethyladamantane, 1-Amino-3,5-diisopropyl-adamantane, 1-Amino-3-methyl-5-ethyladamantane, 1-Amino-3-butyl-5-phenyladamantane, 1-Amino-3-pentyladamantane, 1-Amino-3-dipentyl-adamantane, 1-Amino-3-pentyl-5-hexyladamantane, 1-Amino-3-pentyl-5-cyclohexyladamantane, 1-Amino-3-methyl-5-propyladamantane, 1-Amino-3-methly-5-butyladamantane, 1-Amino-3-methyl-5-pentylada-mantane, 1-Amino-3-methyl-5-hexyladamantane, 1-Am ino-3-methyl-5-cyclohexyladamantane, 1-Amino-3-methyl-5-phenyladamantane, 1Amino-3-ethyl-5-propyladamantane, 1-Amino-3-ethyl-5-butyladamantane, 1-Amino-3-ethyl-5-pentyladamantane, 1-Amino-3,5-dicyclohexylada-mantane, 1-Amino-3-cyclohexyl-5-phenyladamantane, 1-Amino-3,5-di-phenyladamantane, 1-Amino-3,5,7-trimethyladamantane, 1-Amino-3,5-dimethyl-7-ethyladamantane, 1-Amino-3-ethyl-5-hexyladamantane, 1-Amino-3-ethyl-5-cyclohexyladamantane, 1-Amino-3-ethyl-5-phenyl-adamantane, 1-Amino-3-propyl-5-butyladamantane, 1-Amino-3-propyl-5-pentyladamantane, 1-Amino-3-propyl-5-hexyladamantane, 1-Amino-3-propyl-5-cyclohhexyladamantane, 1-Amino-3-propyl-5-phenyladamantane, 1-Amino-3-butyl-5-pentyladamantane, 1-Amino-3-butyl-5-hexyladamantane, 1-Amino-3-butyl-5-cyclohexyladamantane or a pharmaceutically acceptable salt thereof.
13. The process according to claim 1 , wherein the pharmaceutically acceptable salt of 1-aminoadamantane derivative is selected from the group of hydrochloric, hydrobromic methylsufonic, perchloric, sulfuric, phosphoric, acetic, nitric, propionic, glycolic, lactic, pyruvic, malonic, succinic, fumaric, tartaric, citric, benzoic, carbonic, cinnamic, mandelic, methanesulfonic, ethanesulfonic, hydroxyethanesulfonic, benezenesulfonic, p-toluene sulfonic, cyclohecanesulfamic, salicyclic, p-aminosalicylic, 2-phenoxybenzoic, 2-acetoxybenzoic, hydrobromic, hydroiodic, mesylate, phosphate, sulfate.