FIELD: chemistry.
SUBSTANCE: invention relates to a process for the preparation of a crystalline form of deferasirox having a purity of at least 99%, comprising the following steps: (a) reacting salicyloyl chloride with salicylamide in the presence of a catalyst to obtain 2-(2-hydroxyphenyl)benz[e]oxazin-4-one containing less than 1% non-cyclic impurity; or (b) reacting salicyloyl chloride with salicylamide in the presence of a catalyst and a metal base to obtain a 2-(2-hydroxyphenyl)benz[e]oxazin-4-one salt with a metal containing less than 1% non-cyclic impurity; (c) reacting 2-(2-hydroxyphenyl)benz[e]oxazin-4-one from step (a) or the salt of 2-(2-hydroxyphenyl)benz[e]oxazin-4-one with a metal from step (b) with 4-hydrazinobenzoic acid to obtain a half-pure form of deferasirox and (d) purifying the half-pure form of deferasirox in a solvent to obtain a crystalline form of deferasirox having purity of at least 99% wherein said catalyst is a phase transfer catalyst that is a quaternary ammonium halide selected from the group consisting of a tetraalkyl ammonium halide and a benzyltrialkylammonium halide or a combination thereof. Invention also relates to the sodium salt of 2-(2-hydroxyphenyl)benz[e]oxazin-4-one.
EFFECT: technical result: a new method for obtaining the crystalline form of deferasirox with purity of at least 99%, which can be realised commercially.
16 cl, 2 dwg, 11 ex
