Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D413/00—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and oxygen atoms as the only ring hetero atoms
  • C07D413/14—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and oxygen atoms as the only ring hetero atoms containing three or more hetero rings
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P9/00—Drugs for disorders of the cardiovascular system
  • A61P9/12—Antihypertensives

Definitions

• the present invention relates to a method of preparation of the potassium salt of (5 -methyl oxo-l,3-dioxol-4-yl)methyl ester of l-[[2'-(2,5-dihydro-5-oxo-l,2 5 4-oxadiazol-3-yl)[l,l'- biphenyl]-4-yl]methyl]-2-ethoxy-lH-benzimidazole-7-carboxylic acid of formula (T)
• azilsartan medoxomil (I), the synthesis of which is described in EP 1 718 641, EP 2 119 715, is used in the treatment of hypertension.
• Azilsartan medoxomil is a "prodrug" that is easily enzymatically transformed to azilsartan, which is a highly selective antagonist of angiotensin II ATI receptors.
• azilsartan medoxomil is prepared by a reaction of the free azilsartan acid with medoxomil alcohol, which provides azilsartan medoxomil as a solvate with dimethyl acetamide. This is then transformed, by crystallization of the product from an acetone/water mixture, to desolvated azilsartan medoxomil, which is subsequently converted to the potassium salt (I). Disclosure of Invention
• This invention provides a method of preparing the potassium salt of azilsartan medoxomil of formula
• a solvent which is dimethyl acetamide or N-methyl pyrrolidone or their mixtures with other solvents, is prepared, the resulting solvate is optionally re-crystallized, and, in the next step, converted, without desolvating, into the potassium salt using a potassium source.
• the potassium source is, e.g., the potassium salt of 2-ethylhexanoic acid, and the solvent used for the conversion to the potassium salt is, e.g., acetone.
• Azilsartan medoxomil (II) obtained in accordance with the patent EP 2 119 715 exhibits a maximum purity of 98.0% as determined by HPLC. Its desolvation according to the patent from an acetone/water mixture does not virtually achieve any further purification of the substance, nor does re-crystallization from an acetone/water mixture. Then, such raw material is not suitable for pharmaceutical production.
• EP2 1 19 715 Azilsartan medoxomil Crystallized from a 90 % 99.77 % 0.03 % 0.09 % solvate with dimethyl dimethyl
• both the solvates can also be prepared from a non-solvated form of azilsartan medoxomil by crystallization from dimethyl acetamide/isopropyl acetate or N- methyl pyrrolidone/isopropyl acetate mixtures, while the structurally similar dimethyl formamide does not form a solvate under these conditions.
• Solid forms of azilsartan medoxomil can be described with methods commonly used for characterization of the solid phase, such as X-ray Powder Diffraction (XRPD), Differential Scanning Calorimetry (DSC).
• a solvate of azilsartan medoxomil with dimethyl acetamide (1 :1) exhibits the following main characteristic peaks in the X-ray Powder Diffraction measured, with the use of CuKa radiation: 11.0; 12.1 ; 17.2, 25.3 ⁇ 0.2° 2theta, and further the following other characteristic peaks: 11.8; 19.5; 22.2; 24.3 ⁇ 0.2° 2theta.
• Table 2 XRPD - characteristic diffraction peaks corresponding to a solvate of azilsartan medoxomil with dimethyl acetamide.
• a solvate of azilsartan medoxomil with dimethyl acetamide can be prepared by crystallization from dimethyl acetamide and another solvent in which azilsartan medoxomil only dissolves to a limited extent, such as isopropyl acetate, isobutyl acetate, ethyl acetate, methyl acetate, acetone, methyl ethyl ketone and methyl isobutyl ketone. Crystallization is carried out at a temperature in the range of from 10°C to 100°C.
• the potassium salt of azilsartan medoxomil is characterized by the following main peaks, measured with the use of CuKa radiation: 6.15°, 13.96°, 18.72° and 21.37° 2 ⁇ ⁇ 0.2° 2 ⁇ .
• the characteristic XRPD peaks are presented in Table 3.and an XRPD record in Fig. 1. This form is further characterized with a Differential Scanning Calorimetry (DSC) record, see Fig.2.
• a solvate of azilsartan medoxomil with N-methyl pyrrolidone is characterized by the following main characteristic peaks in an X-ray Powder record, measured with the use of CuKa radiation: 10.9; 16.3; 17.2; 18.9; ⁇ 0.2° 2theta.
• the characteristic XRPD peaks are presented in Table 4 and the XRPD record in Fig 5. This form is further characterized with a Differential Scanning Calorimetry (DSC) record, see Fig. 6.
• DSC Differential Scanning Calorimetry
• Table 4 XRPD - characteristic diffraction peaks corresponding to a solvate of azilsartan medoxomil with N-methyl pyrrolidone.
• a solvate of azilsartan medoxomil with N-methyl pyrrolidone can be prepared by crystallization from N-methyl pyrrolidone and another solvent in which azilsartan only dissolves to a limited extent, such as isopropyl acetate, isobutyl acetate, ethyl acetate, methyl acetate, acetone, methyl ethyl ketone and methyl isobutyl ketone. Crystallization is carried out at a temperature in the range of from 10°C to 100°C.
• Fig. 1 X PD record for the potassium salt of azilsartan medoxomil
• Fig. 2 DSC record for the potassium salt of azilsartan medoxomil
• Fig. 3 XRPD record for a solvate of azilsartan medoxomil with dimethyl acetamide
• Fig. 4 DSC record for a solvate of azilsartan medoxomil with dimethyl acetamide
• Fig. 5 XRPD record for a solvate of azilsartan medoxomil with N-methyl pyrrolidone
• Fig. 6 DSC record for a solvate of azilsartan medoxomil with N-methyl pyrrolidone
• Soller diaphragms 0.02 rad and an anti-dispersion diaphragm 1 ⁇ 4 were used.
• Soller diaphragms 0.02 rad and an anti-dispersion diaphragm 5.0 mm were used.
• the Differential Scanning Calorimetry (DSC) records were measured with a DSC Pyris 1 device made by Perkin Elmer.
• the charge of the sample in a standard Al pot was between 3-4 mg and the heating-up rate was 10°C/min.
• the temperature program used consists of 1 minute of stabilization at the temperature of 50°C and then of heating to 250°C at the heating-up rate of 10°C/min.
• As the carrier gas 4.0 N 2 was used at the flow of 20 ml/min.
• Example 4 Preparation of azilsartan medoxomil as a solvate with dimethyl acetamide Crude azilsartan medoxomil prepared in accordance with Example 2 was dissolved in a mixture of dimethyl acetamide (4 ml) with isopropyl acetate (6 ml) in a hot state; after cooling and aspiration, 3.6 g (90 %) of the product was obtained, HPLC purity 99.77 %.
• Example 5 Preparation of azilsartan medoxomil as a solvate withN-methyl pyrrolidone Crude azilsartan medoxomil prepared in accordance with Example 2 was dissolved in a mixture of N-methyl pyrrolidone (4 ml) with isopropyl acetate (7 ml) in a hot state; after cooling and aspiration, 2.8 g (69 %) of the product was obtained, HPLC purity 99.84 %.
• Example 6 Preparation of the potassium salt of azilsartan medoxomil
• Example 8 Preparation of the ethyl ester of 2-ethoxy-l-((2'-(5-oxo-4,5-dihydro-l,2,4- oxadiazol-3-yl)biphenyl-4-yl)methyl)-lH-benzo[i/]-imidazole-7-carboxylic acid (V).
• the starting amidoxime (IV) was suspended in diethyl carbonate (30 g) and sodium ethoxide (21 % in ethanol, 9 g) was added. The mixture was heated at 80°C for 2h, 20 ml of the solvent was removed by distillation, ethanol (20 ml), water (20 ml) and acetic acid (3 g) and more water (20 ml) were added. The suspension was stirred at 50°C for 1 h and cooled to 25°C. 8 g (76 %) of the product was obtained.
• the starting ethyl ester of azilsartan (V, 250 g) was suspended in a solution of sodium hydroxide in water (56 g/800ml). The suspension was heated at 50°C for 4 h, after pH adjustment to 4-5, the product crystallized providing 232 g (98.5 %).

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• 2012
  • 2012-09-26 CZ CZ2012-663A patent/CZ305318B6/cs not_active IP Right Cessation
• 2013
  • 2013-09-25 KR KR1020157007800A patent/KR20150060733A/ko not_active Application Discontinuation
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  • 2013-09-25 CN CN201380050044.9A patent/CN104662019A/zh active Pending
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