Method for obtaining a pharmaceutically active compound (Irbesartan) and its synthesis intermediate

Method for obtaining a pharmaceutically active compound, Irbesartan polymorph A, or a pharmaceutically acceptable salt thereof, which comprises:

• (a) a coupling reaction of the compound of formula (II) with the 2-(1H-tetrazol-5-yl)phenylboronic acid of formula (III):
• in a solvent medium selected from an organic polar or aqueous solvent, or a mixture of water and water-miscible solvent or a biphasic system, in the presence of an organic or inorganic base, capable of forming a salt with the tetrazole ring of the compound of formula (III), at a temperature between 25 and 150° C., with a palladium catalyst and, if required, a phosphine ligand, to obtain Irbesartan (1):
• in the form of an aqueous solution of one its organic- or inorganic-base salts;
• (b) the preceding aqueous alkaline solution is acidified to pH 4.8 to 5.2 and the precipitate so obtained is filtered;
• and
• (c) the product of stage (b) is recrystallised in the presence of an organic solvent or a mixture thereof with water to give Irbesartan polymorph A with the following X-ray diffraction spectrum:
• Pos.[°2Th.]
• d-spacing [Å]
• Rel. Int.[%]
• 4.76
• 18.561
• 100
• 8.20
• 10.783
• 2.71
• 9.43
• 9.377
• 2.8
• 10.54
• 8.396
• 1.72
• 12.50
• 7.080
• 35.21
• 13.32
• 6.646
• 4.4
• 14.13
• 6.268
• 1.8
• 16.37
• 5.415
• 1.61
• 17.03
• 5.207
• 8.25
• 17.67
• 5.021
• 3.06
• 18.90
• 4.696
• 3.76
• 19.44
• 4.567
• 13.86
• 20.06
• 4.426
• 8.16
• 20.59
• 4.314
• 6.94
• 21.13
• 4.204
• 7.03
• 21.69
• 4.097
• 6.4
• 22.67
• 3.923
• 5.66
• 23.19
• 3.835
• 11.07
• 23.68
• 3.758
• 7.84
• 26.42
• 3.374
• 1.27
• 26.83
• 3.324
• 2.05
• 27.70
• 3.220
• 3.22
• 28.52
• 3.130
• 2.57
• 31.96
• 2.800
• 1.52
• 33.06
• 2.710
• 1.82.