Cimicoxib

Cimicoxib

Uriach (Originator)

4-[4-Chloro-5-(3-fluoro-4-methoxyphenyl)-1H-imidazol-1-yl]benzenesulfonamide

IN PHASE 2

Cimicoxib (trade name Cimalgex) is a non-steroidal anti-inflammatory drug (NSAID) used in veterinary medicine to treat dogs for pain and inflammation associated with osteoarthritis and for the management of pain and inflammation associated with surgery.^[1] It acts as a COX-2 inhibitor.

Cimicoxib is a selective COX-2 inhibitor being developed by Affectis as a treatment for depression and schizophrenia. If approved, Cimicoxib would be the first drug in decades to treat depression by a new mechanism of action

Cimicoxib, an imidazole derivative, is a selective cyclooxygenase-2 (COX-2) inhibitor. The product was in phase II development at Affectis Pharmaceuticals for the oral treatment of major depression, however, no recent development have been reported. Originally developed by Uriach, the compound was acquired by Palau Pharma, a spin-off created by Uriach in November 2006.

In 2007, Palau Pharma licensed global rights to cimicoxib to Affectis Pharmaceuticals for all CNS indications. Palau had been clinically evaluating the compound for the treatment of osteoarthritis, pain and rheumatoid arthritis, however, no recent development has been reported for these indications. The compound holds potential for the treatment of schizophrenia.

Treatment of 4-(acetylamino)phenylsulfonyl chloride (I) with tert-butylamine yields sulfonamide (II), which on deprotection with potassium hydroxide gives amine (III). Reaction of compound (III) with 4-methoxy-3-fluorobenz-aldehyde gives imine (IV), which is cyclized with tosylmethyl isocyanide to afford imidazole (V). Regioselective chlorination of compound (V) with N-chlorosuccinimide (NCS) to afford the chloroimidazole (VI) and then deprotection of the sulfonamide group of (VI) yields cimicoxib in 40% overall yield.

EP 1122243; JP 2002527508; WO 0023426, ES 2184633; WO 0316285

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http://www.google.com/patents/EP1424329A1?cl=en

EXAMPLE 1

4-Amino-N- tert -butylbenzenesulfonamide Method A:

• [0031]

a) N-tert-Butyl-4-nitrobenzenesulfonamide

• [0032]
  To a solution of tert-butylamine (0.47 L, 6.4 mol) in THF (0.55 L) is slowly added, at 0 °C, a solution of 4-nitrobenzenesulfonyl chloride (50 g, 0.23 mol) in THF (0.55 L) and the resulting mixture is stirred for 24 h at room temperature. The solvent is removed and the residue is taken up in a CHCl₃/0.5 N HCl mixture, the layers are separated and the aqueous phase is extracted with CHCl₃. The combined organic extracts are washed with H₂O and brine and dried over MgSO₄. The solvent is removed, yielding 56.3 g of a yellowish solid which is directly used in the next reaction (yield: 97%).
  Mp: 105-109°C; ¹H-NMR (300 MHz, CDCl₃) δ (TMS): 1.29 (s, 9 H), 5.07 (s, 1 H), 8.13 (d, J = 9 Hz, 2 H), 8.39 (d, J = 9 Hz, 2 H).

b) Title compound

• [0033]
  A solution of N-tert-butyl-4-nitrobenzenesulfonamide (10.0 g, 39 mmol) in EtOH (100 mL) is stirred for 48 h under a H₂ atmosphere in the presence of 10% Pd/C (1.50 g). The resulting mixture is filtered and concentrated to give the desired product as a slightly-coloured solid (8.7 g, yield: 98%).
  Mp: 127 °C; ¹H-NMR (300 MHz, CDCl₃ + CD₃OD) δ (TMS): 1.19 (s, 9 H), 3.74 (s, CD₃OD + 1 H), 6.93 (d, J = 9 Hz, 2 H), 7.66 (d, J = 9 Hz, 2 H).

Method B:

• [0034]

a) 4-Acetylamino-N-tert-butylbenzenesulfonamide

• [0035]
  To a suspension of 4-acetylaminobenzenesulfonyl chloride (10 g, 43 mmol) in DME (103 mL) is added, at 0 °C, tert-butylamine (9 mL, 86 mmol) in DME (103 mL). Next, the reaction mixture is stirred for 4 h at reflux. The solvent is removed and CHCl₃ is added. The resulting suspension is filtered and the solid is washed with CHCl₃, H₂O and Et₂O. The solid obtained is dried in vacuo to give 8.0 g of the product as a white solid (yield: 68%).
  Mp: 200-201 °C; ¹H-NMR (300 MHz, CDCl₃ + CD₃OD) δ (TMS): 1.15 (s, 9 H), 2.12 (s, 3 H), 4.21 (s, 2H + CD₃OD), 7.66 (d, J = 9 Hz, 2 H), 7.75 (d, J = 9 Hz, 2 H).

b) Title compound

• [0036]
  A solution of 4-acetylamino-N-tert-butylbenzenesulfonamide (8.0 g, 29.6 mmol), KOH (8.30 g, 148 mmol), H₂O (6 mL) and MeOH (24 mL) is heated at 100°C for 2 h. H₂O (24 mL) is added and the mixture is heated for two more hours. It is allowed to cool, H₂O is added and it is brought to pH 8 with 1N HCl. It is then extracted with EtOAc, dried over Na₂SO₄ and the solvent is removed, to give 6.0 g of the product as a white solid (yield: 89%).

EXAMPLE 2 N- tert -Butyl-4-[(3-fluoro-4-methoxybenzylidene)amino]benzenesulfonamide

• [0037]
• [0038]
  A mixture of 4-amino-N-tert-butylbenzenesulfonamide (52.3 g, 0.23 mol, obtained in example 1), 3-fluoro-4-methoxybenzaldehyde (35.3 g, 0.23 mol) and toluene (2.5 L) is heated at reflux in a Dean-Stark for 24 h. The solvent is removed, yielding 83.5 g of the title compound (yield: quantitative).
  Mp: 129-131 °C; ¹H-NMR (300 MHz, CDCl₃) δ (TMS): 1.23 (s, 9 H), 3.98 (s, 3 H), 4.65 (s, 1 H), 7.04 (t, J = 8.1 Hz, 1 H), 7.21 (d, J = 6.7 Hz, 2 H), 7.58 (m, 1 H), 7.73 (dd, J_H-F = 11.8 Hz, J = 2 Hz, 1 H), 7.90 (d, J = 6.7 Hz, 2 H), 8.33 (s, 1 H).

EXAMPLE 3 N-tert-Butyl-4-[5-(3-fluoro-4-methoxyphenyl)imidazol-1-yl]benzenesulfonamide

• [0039]
• [0040]
  A mixture of N-tert-butyl-4-[(3-fluoro-4-methoxybenzylidene)amino]benzenesulfonamide (41.5 g, 114 mmol, obtained in example 2), tosylmethylisocyanide (33.22 g, 171 mmol), K₂CO₃ (31.1 g, 228 mmol), DME (340 mL) and MeOH (778 mL) is heated at reflux for 3 h. The solvent is removed and the residue is taken up in a CHCl₃/H₂O mixture and the layers are separated. The aqueous phase is extracted with CHCl₃ and the combined organic extracts are dried over MgSO₄ and concentrated. A crude product is obtained, which is washed with Et₂O several times to give 41.40 g of a creamy solid that is directly used in the next reaction (yield: 90%).
  Mp: 229-232°C; ¹H-NMR (300 MHz, CDCl₃) δ (TMS): 1.24 (s, 9 H), 3.89 (s, 3 H), 4.51 (s, 1 H), 6.90 (m, 3 H), 7.23 (s, 1 H), 7.29 (d, J = 8.7 Hz, 2 H), 7.73 (s, 1 H), 7.94 (d, J = 8.7 Hz, 2 H).

EXAMPLE 4 N-tert-Butyl-4-[4-chloro-5-(3-fluoro-4-methoxyphenyl)imidazol-1-yl]benzenesulfonamide

• [0041]
• [0042]
  A mixture of N-tert-butyl-4-[5-(3-fluoro-4-methoxyphenyl)imidazol-1-yl]benzenesulfonamide (41.40 g, 103 mmol, obtained in example 3) and acetonitrile (840 mL) is heated at reflux and acetonitrile is added until complete dissolution (200 mL more). Next, N-chlorosuccinimide (15.0 g, 113 mmol) is added and the mixture is refluxed for 24 h. The solvent is removed and the residue is suspended in EtOAc and 1N HCl and is stirred for 10 min. The solid obtained is filtered and washed directly in the filter with 1N HCl, 1N NaOH, saturated NH₄Cl solution, H₂O and Et₂O. A solid is obtained, which is dried in vacuo to give 37.0 g of the product as a creamy solid (yield: 82%).
  Mp: 208-210 °C; ¹H-NMR (300 MHz, CDCl₃) δ (TMS): 1.24 (s, 9 H), 3.89 (s, 3 H), 4.51 (s, 1 H), 6.90 (m, 3 H), 7.23 (d, J = 8.7 Hz, 2 H), 7.63 (s, 1 H), 7.92 (d, J = 8.7 Hz, 2 H).

EXAMPLE 5 4-[4-Chloro-5-(3-fluoro-4-methoxyphenyl)imidazol-1-yl]benzenesulfonamide

• [0043]
• [0044]
  A mixture of N-tert-butyl-4-[4-chloro-5-(3-fluoro-4-methoxyphenyl)imidazol-1-yl]benzenesulfonamide (37.0 g, 85 mmol, obtained in example 4), concentrated HCl (200 mL) and H₂O (200 mL) is heated at reflux for 3 h. The mixture is allowed to cool and is brought to pH 6 with 6N NaOH. A white precipitate appears, which is collected by filtration and washed with plenty of H₂O and then with CHCl₃. 31 g of the title compound of the example is obtained (yield: 97%), which are recrystallized from acetonitrile.
  Mp: 211-212 °C;
• ¹H-NMR (300 MHz, CDCl₃ + CD₃OD) δ (TMS): 3.90 (s, 3 H), 4.16 (s, CD₃OD + 2 H), 6.93 (m, 3 H), 7.30 (d, J = 8.6 Hz, 2 H), 7.73 (s, 1 H), 7.95 (d, J = 8.7 Hz, 2 H).

References