Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D487/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00
  • C07D487/02—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00 in which the condensed system contains two hetero rings
  • C07D487/04—Ortho-condensed systems

Definitions

• the present invention relates to new and improved processes for the preparation of Alcaftadine and pharmaceutically acceptable salts thereof as well as an intermediate for the preparation of Alcaftadine.
• EP 0 588 858 describes the preparation of Alcaftadine for the first time through the process :
• it concerns a process for preparing Alcaftadine or a pharmaceutically acceptable salt thereof reacting the acid addition salt of formula 7 with formaldehyde to the compound of formula 11 or a salt thereof and then oxidizing the compound of formula 11 or a salt thereof to Alcaftadine:
• Alcaftadine to a pharmaceutically acceptable salt thereof, wherein the acid addition salt of formula 7 is a salt formed with a di-carboxylic acid, HA, such as fumaric acid, maleic acid, succinic acid, or tartaric acid .
• HA such as fumaric acid, maleic acid, succinic acid, or tartaric acid .
• This process converts the acid addition salt of formula 7 directly to the compound of formula 11 without the need for protecting with ethyl carboxylate and therefore saves three reaction steps. Furthermore, the yield is significantly increased and the reaction time for introducing the hydroxymethyl group has been reduced to less than two days. This, in turn, decreases the risk of introducing a second hydroxymethyl group into the compound in a quantitative amount.
• a further aspect of the invention concerns a process for the preparation of Alcaftadine or a pharmaceutically acceptable salt thereof comprising reacting a compound of formula 1 with ethyl l-methylpiperidine-4-carboxylate in the presence of a strong base to provide a compound of formula 4, which is further reacted with trifluoromethanesulfonic acid and subsequently a di-carboxylic acid, HA, as defined above to provide the acid addition salt of formula 7 : and further reacting the acid addition salt of formula 7 to provide Alcaftadine or, optionally, a pharmaceutically acceptable salt thereof.
• the method herein provides Alcaftadine in a yield and purity superior to the methods known in the art. Furthermore, it has been found that careful selection of crystallization solvents will provide Alcaftadine in a purity higher than 99%.
• yet a further aspect of the invention concerns a process for the isolation and purification of Alcaftadine comprising crystallization in isopropyl alcohol or ethyl acetate.
• the neutral form of the acid addition salt of formula 7 is known from EP 0 588 858, but the acid addition salt of formula 7 is a novel compound.
• strong base is intended to mean a base sufficiently strong to remove a hydrogen from position 2 of the imidazole ring in the compound of formula 1.
• bases are well known to the person skilled in the art and include inter alia lithium diisopropylamide, hexyl-lithium, butyl- lithium, and lithium hexamethyldisilazide.
• di-carboxylic acid is intended to mean an organic acid with two or more carboxyiic acid groups and a total of 2 to 10 carbon atoms in the molecule.
• di-carboxylic acid includes, by way of example, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, tartaric acid, EDTA, citric acid, fumaric acid, maleic acid, glutaconic acid, muconic acid, phthalic acid, isophthalic acid, terephthalic acid, and malic acid .
• it concerns a process for preparing Alcaftadine or a pharmaceutically acceptable salt thereof reacting the acid addition salt of formula 7 with formaldehyde, optionally in the presence of a base, to the compound of formula 11 or a salt thereof and then oxidizing the compound of formula 11 or a salt thereof to Alcaftadine:
• Alcaftadine to a pharmaceutically acceptable salt thereof, wherein the acid addition salt of formula 7 is a salt formed with a di-carboxylic acid, HA, such as fumaric acid, maleic acid, succinic acid, or tartaric acid .
• HA such as fumaric acid, maleic acid, succinic acid, or tartaric acid .
• the acid addition salt of formula 7 is formed by reacting the compound of formula 1 with ethyl l-methylpiperidine-4-carboxylate in the presence of a strong base to provide a compound of formula 4, which is further reacted with trifluoromethanesulfonic acid and subsequently a di-carboxylic acid, HA, as defined above to provide the acid addition salt of formula 7 :
• said strong base is lithium diisopropylamide or hexyl lithium.
• a further aspect of the invention concerns a process for the preparation of Alcaftadine or a pharmaceutically acceptable salt thereof comprising reacting a compound of formula 1 with ethyl l-methylpiperidine-4-carboxylate in the presence of a strong base to provide a compound of formula 4, which is further reacted with trifluoromethanesulfonic acid and subsequently a di-carboxylic acid, HA, as defined above to provide the acid addition salt of formula 7 :
• said strong base is lithium diisopropylamide or hexyl lithium.
• a further aspect of the invention concerns a process for the isolation and purification of Alcaftadine comprising crystallization in isopropyl alcohol or ethyl acetate.
• the di-carboxylic acid serves a double function in that it both facilitates the purification of the acid addition salt of formula 7 by crystallization and at the same time provides a much better starting point for introducing the hydroxymethyl group into the molecule than the correspond ing neutral compound .
• the corresponding reaction from the corresponding neutral base to the compound of formula 11 lasts at least 1 week, whereas taking the acid add ition salt of formula 7 as the starting point means that the reaction only needs about 20 to 40 hours to complete.
• the di-carboxylic acid may in one embod iment be selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, tartaric acid, EDTA, citric acid, fumaric acid, maleic acid, g lutaconic acid, muconic acid, phthalic acid, isophthalic acid, terephthalic acid, and malic acid .
• said di-carboxylic acid is selected from the group consisting of fumaric acid, maleic acid, succinic acid, and tartaric acid .
• said di-carboxylic acid is fumaric acid or succinic acid .
• said d i- carboxylic acid is fumaric acid .
• said di-carboxylic acid is succinic acid .
• oxidation reagents used in the art for selectively oxidizing primary alcohols to the corresponding aldehyde.
• These oxidation reagents include chromium-based reagents, such as Collins
• DMSO methyl methacrylate
• electrophiles such as oxalyl chloride (Swern oxidation), a carbodiimide (Pfitzner-Moffatt oxidation) or the complex S03- Py (Parikh-Doering oxidation) ; hypervalent iod ine compounds, such as Dess-Martin period inane or 2-Iodoxybenzoic acid ;
• catalytic tetrapropylammonium perruthenate in the presence of excess of N- methylmorpholine N-oxide (Ley oxidation) ; catalytic TEMPO in the presence of excess sodium hypochlorite (Anelli's oxidation) ; or manganese dioxide.
• the oxidation reagent in the reaction from the compound of formula 11 to the compound of formula 12 is manganese d ioxide, Mn0 2 .
• the reaction between the compound of formula 1 and l-methylpiperidine-4- carboxylate is carried out in the presence of a strong base, as defined above.
• bases meeting this definition are well known to the skilled person and include hexyl-lithium, butyl-lithium, lithium hexamethyldisilazide, and sodium hydride.
• said strong base is lithium diisopropylamide.
• the reaction temperature is advantageously kept in the range -80°C to -30°C, such as in the range -80°C to -40°C, e.g . in the range -80°C to -60°C.
• 1 to 3 equivalents of l-methylpiperidine-4-carboxylate are added to the compound of formula 1.
• 1.5 to 2.6 equivalents of l-methylpiperidine-4-carboxylate are added to the compound of formula 1.
• the reaction solvent used is advantageously an aprotic solvent.
• the solvent is tetrahydrofuran, toluene, or a mixture thereof.
• the resulting product, the compound of formula 4 may be isolated in acetone, ethyl acetate, or dichloromethane in the form of the hydrochloride or the hydrobromide.
• the overall yield of the reaction is up to 85%.
• the ring closure of the compound of formula 4 may be achieved by adding trifluoromethanesulfonic acid as the only acid component.
• the reaction is carried out at a temperature between 70 and 130°C using 4 to 20 volumes of trifluoromethanesulfonic acid .
• the reaction is carried out at a temperature between 70 and 130°C, such as a temperature between 90 and 130°C, e.g . between 110 and 130°C.
• the reaction is carried out using between 4 and 20 volumes of
• trifluoromethanesulfonic acid such as between 10 and 20 volumes, e.g. between 15 and 20 volumes.
• the resulting product may be purified by crystallization by adding the di- carboxylic acid, HA, to form the acid addition salt of formula 7.
• suitable solvents for the crystallization include acetone, methanol, ethyl acetate, isopropyl alcohol, and mixtures thereof.
• said solvent for the crystallization of the acid addition salt of formula 7 is selected from acetone, isopropyl alcohol, and mixtures thereof.
• the acid addition salt of formula 7 may be used as the starting point in purified or non-purified form. In both cases, the reaction time is reduced considerably compared to taking the corresponding neutral base as the starting point, even if the neutral compound is in purified form.
• the reaction between the acid addition salt of formula 7 and formaldehyde is advantageously carried out with heating, such as at a temperature between 80 and 100°C, in an aqueous solvent or in combination with an organic solvent such as Toluene, Xylene or heptane. Furthermore, the reaction between the acid addition salt of formula 7 and formaldehyde is advantageously carried out in the presence of a base.
• said base is selected from the group consisting of carboxylate, such as acetate; carbonate or bicarbonate; pyridine; and benzyltrimethylammonium hydroxide.
• said base is a carboxylate or bicarbonate.
• said base is acetate.
• said base is sodium acetate.
• said base is sodium acetate, sodium bicarbonate or pyridine. The overall yield of the reaction is 70-75%.
• the yield and purity of the direct product of the reaction, the compound of formula 11, facilitates its purification on an industrial scale, such as by crystallization of the fumarate salt in acetone as solvent or by crystallization of the succinate salt in Ethyl acetate as solvent.
• Acetonitrile is a suitable solvent for the crystallization of the compound of formula 11 as a base.
• reaction conditions for the oxidation reaction may depend on the chosen oxidation reagent.
• the reaction may be carried out under similar circumstances as those disclosed in EP 0 588 858 (example 51).
• the product (Alcaftadine) may be isolated and purified from solvents such as isopropanol, ethyl acetate, or isopropyl ether.
• solvents such as isopropanol, ethyl acetate, or isopropyl ether.
• Isopropanol and ethyl acetate may advantageously be used as solvents for the purification with a final yield of 50- 65%.
• a further aspect of the invention concerns a process for the isolation and purification of Alcaftadine comprising crystallization in isopropyl alcohol or ethyl acetate.
• the process of the invention involves a novel intermediate, which has not previously been used in the preparation of Alcaftadine.
• a further aspect of the invention concerns the acid addition salt of formula 7.
• N-(2-phenyl)-ethyl imidazole (20 g, 0.12 mol) was dissolved in a mixture of toluene (100 ml) and tetrahydrofuran (60 ml). The solution formed was cooled down to -50° C and then a solution of LDA (lithium diisopropylamide) 2 M in tetrahydrofuran (128 ml, 0.26 mol) was added . The temperature was kept at -50° C for 15 minutes and then a solution of N-methyl ethyl isonipecotate (48.1 g, 0.28 mol) in toluene (50 ml) was added . After 1 hour at -50° C the reaction was quenched by addition of water (200 ml).
• LDA lithium diisopropylamide
• N-(2-phenyl)-ethyl imidazole (7.9 g, 0.046 mol) was disolved in a mixture of toluene (40 ml) and tetrahydrofuran (24 ml). The solution formed was cooled down to -50° C and then a solution of hexyllithium 2.7 M in hexane (37.5 ml, 0.101 mol) was added. The temperature was kept at -50° C for 15 minutes and then a solution of N-methyl ethyl isonipecotate (19.0 g, 0.11 mol) in toluene (20 ml) was added. After 1 hour at -50° C the reaction was quenched by addition of water (80 ml).
• the solution was cooled to 25° C and poured into into water (30 ml) at 0/5° C.
• the pH was adjusted to 9/10 by addition of 50% aqueous NaOH and the product was extracted with dichloromethane.
• the reaction was cooled to 20° C, the pH was adjusted to 9-10 by addition of 50% aqueous NaOH and the product was extracted with dichloromethane.
• the solvent was distilled and changed to acetone to a final volume of 40 ml.
• the reaction was cooled to 20° C, and the two phases were separated.
• the pH of the aqueous phase containing the product was adjusted to 9-10 by addition of 50% aqueous NaOH and the product was extracted with dichloromethane.
• Example 20 comparative example
• the reaction was cooled to 20° C, the pH was adjusted to 9-10 by addition of 50% aqueous NaOH and the product was extracted with dichloromethane.
• the reaction was cooled to 20° C, and the two phases were separated.
• the pH of the aqueous phase containing the product was adjusted to 9-10 by addition of 50% aqueous NaOH and the product was extracted with dichloromethane.
• the reaction was cooled to 20° C.
• the pH was adjusted to 9-10 by addition of 50% aqueous NaOH and the product was extracted with dichloromethane.
• the organic phase was concentrated to a final volume of 30 ml, manganese (IV) oxide (25 g) and water (3 ml) were added and the suspension was refluxed for 2 hours.
• the reaction mixture was cooled down to 20° C.
• the solids were filtered off and washed with dichloromethane (50 ml).
• the filtered liquids were concentrated to a final volume of 15 ml and diisopropyl ether (100 ml) was added.
• the solid was filtered and washed with diisopropylether. Crude Alcaftadine (4.7 g) was obtained with >90 % purity.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Plural Heterocyclic Compounds (AREA)
• Nitrogen Condensed Heterocyclic Rings (AREA)

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• 2014
  • 2014-03-24 CA CA2907396A patent/CA2907396C/en active Active
  • 2014-03-24 KR KR1020157030845A patent/KR102204578B1/ko active Active
  • 2014-03-24 ES ES14712650.2T patent/ES2680933T3/es active Active
  • 2014-03-24 WO PCT/EP2014/055815 patent/WO2014154620A1/en not_active Ceased
  • 2014-03-24 EP EP14712650.2A patent/EP2978765B1/en active Active
  • 2014-03-24 JP JP2016504606A patent/JP6400672B2/ja active Active
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