TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The step (C1) comprises a sub-step between the steps (c) and (d), in which an active carbon is added to the organic phase previously separated during the step (c) and later removed by filtration. The crystallization operation comprises: performing a first alkalinization for 30-60 minutes, up to a pH of 0.8-1.2 is reached, keeping the temperature lower than 15 degrees C, and a crystallization break at a temperature of 0-5 degrees C for 2-3 hours; performing a second alkalinization for 15-30 minutes, up to a pH value of 2.5-3.5 is reached, and a crystallization break at a temperature of 0-5 degrees C for 1-2 hours; and performing a third alkalinization for 5-15 minutes, up to a pH value of 5-7 is reached, and a crystallization break at a temperature of 0-5 degrees C for 1-2 hours. The first, second and third alkalinization steps are performed by using a basic solution comprising sodium hydroxide solution, potassium hydroxide solution, lithium hydroxide solution or ammonia solution, where the first alkalinization step uses 30 wt.% of sodium hydroxide solution, and the second and third alkalinization steps use 2 wt.% of sodium hydroxide solution. The nucleophilic substitution reaction takes place at a temperature of 0-10 degrees C. The method comprises a solvent change step that is interposed between the steps (A1) and (B1), in which: the solution resulting from the bromination reaction is subjected to at least one extraction with water and subsequently to a distillation for the removal of the ester solvent; and the organic mixture comprising unreacted 2,2'-(5-methyl-1,3-phenylene)bis(2-methylpropanenitrile), formed 2-(3-bromoethyl-5-(cyano-dimethyl-methyl)-phenyl)-2-methyl-propanenitrile and other reaction by-products is subsequently dissolved in dimethylformamide. In the method: during the steps (c) and (d), the respective acid solution used is water solution of hydrogen chloride, water solution of sulfuric acid and water solution of hydrobromic acid; and during the step (C1), a mixture of toluene and water is added to the solution resulting from the nucleophilic substitution reaction. Preferred Components: The ester solvent is tert-butyl acetate, isopropyl acetate, isobutyl acetate or ethyl acetate. ACTIVITY - Cytostatic.    MECHANISM OF ACTION - None given.    EXAMPLE - 10 g Of 2-(3-(cyano-dimethyl-methyl)-5-methyl-phenyl)-2-methyl-propionitrile or 2-(3-(cyano-dimethyl-methyl)-5-hydroxymethyl-phenyl)-2-methyl-propionitrile, and 100 ml of tert-butyl acetate were loaded in a flask, and the resulting suspension was kept under stirring at ambient temperature. Then 8.3 g of N-bromosuccinimide followed by 220 mg of catalyst azobisisobutyronitrile were added to the obtained suspension, and the resulting mixture was heated and kept at a temperature of 65-75 degrees C for 2-4 hours. Then the reaction quenching was performed by lowering the temperature of the reaction mixture to 30-40 degrees C and adding 50 ml of a 5% solution of sodium metabisulfite. Then an organic rich phase was separated from the water phase and washed with distilled water. Then 80 ml of dimethylformamide was added to the rich solution, after the latter had been concentrated in a vacuum. The obtained solution was then re-distilled to eliminate the residual tert-butyl acetate solvent. Then 4.47 g of sodium 1,2,4-triazole was added to the obtained solution, after the latter had been brought to a temperature of 0-25 degrees C (preferably 5-10 degrees C). The obtained reaction mixture was then kept under stirring for 1-2 hours. The reaction was quenched by the addition of 100 ml toluene and 125 ml distilled water. After separation of the phases, the rich organic phase was treated with a water solution of 0.1M hydrogen chloride. After separation of the phases, 1 g of carbon was added to the resulting organic phase and kept under stirring at ambient temperature. After filtering, the clarified organic phase was extracted twice with 100 ml of 2 M hydrogen chloride. The rich water phase containing high purity dissolved anastrozole was lastly back-washed with toluene. The temperature was maintained below 15 degrees C, and a solution of 30 wt.% sodium hydroxide was added to the rich acid solution in 60-90 minutes until pH 1 was reached. The mixture was then left in crystallization break at 0-5 degrees C for 2 hours. Then a solution of 0.5 M sodium hydroxide was added until a pH of 2.5-3.5 was obtained. The resulting suspension was then left in break at 0-5 degrees C for a further 2 hours. Then 0.5 M sodium hydroxide solution was then added to the mixture until a final pH of 6-7 was reached, followed by a last break at 0-5 degrees C. The resultant product was then filtered, washed with distilled water and dried in a vacuum at 50 degrees C to obtain the anastrozole.