Process for obtaining olopatadine and intermediates

A process for obtaining a compound of general formula (II)

• wherein
• Y is
• OR1, wherein R1 is C1-C7 alkyl, C3-C7 cycloalkyl, aryl, or heterocycle;
• or
• NR2R3, wherein R2 and R3, independently from each other, are C1-C7 alkyl, aryl, or R2 and R3 together with the nitrogen atom to which they are bound form a heterocycle of 3 to 7 members,
• or a solvate or a salt thereof,
• comprising
• a) reacting a compound of general formula (III)
• wherein Y has the previously mentioned meaning,
• with a Wittig reagent selected from the group consisting of a (3-dimethylaminopropyl)triphenylphosphonium halide and salts thereof, under Wittig reaction conditions, in the presence of a base in a reaction medium comprising an organic solvent, for obtaining a compound of general formula (II);
• and
• b) optionally, converting the compound of general formula (II) into a solvate or into a salt thereof.