Process for preparing methyl {4,6-diamino-2-[5-fluoro-1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]pyrimidin-5-yl} carbamate

A process for preparing methyl {4,6-diamino-2-[5-fluoro-1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]pyrimidin-5-yl}carbamate of the formula (I)

• in a crystalline form of modification I, wherein the x-ray diffractogram of the compound of the formula (I) in modification I exhibits peak maxima of the 2 theta angle at 5.9, 6.9, and 22.7, comprising:
• preparing a hydrochloride of the compound of the formula (I)
• by heating a compound of formula (IX),
• in tetrahydrofuran as solvent, adding 1.0 eq. to 1.2 eq. methyl chloroformate, stirring within a reaction time of 1 h to 10 h, and isolating the hydrochloride of the compound of the formula (I);
• subsequently preparing a di-dimethyl sulfoxide (di-DMSO) solvate of the compound of the formula (I)
• di-DMSO solvate
• by dissolving the hydrochloride of the compound of the formula (I) in DMSO, adding tri-n-butylamine and activated carbon, removing the activated carbon, crystallizing the di-DMSO solvate by cooling and adding ethyl acetate, isolating the di-DMSO solvate in crystallized form, and washing with a mixture of DMSO and ethyl acetate;
• and subsequently preparing the compound of the formula (I) in the crystalline form of modification I by
• 1.1 dissolving the di-DMSO solvate of the compound of the formula (I) in DMSO, and adding ethanol in a ratio of DMSO to ethanol of 2:1 to 6:1 w/w,
• 1.2 crystallizing the dissolved compound of the formula (I) out of the solution by addition of water,
• 1.3 cooling the suspension formed to a temperature of 5° C. to 50° C. and
• 1.4 agglomerating the crystals formed in step 1.2 from the cooled suspension in step 1.3 to afford active compound product by adding isopropyl acetate, wherein the ratio of the mass of isopropyl acetate to the sum of the mass of the compound of the formula (I) plus the mass of ethanol is 0.3 to 2.0.