| abstract |
Process for preparing olopatadine or a salt thereof by a wittig reaction of 11-oxo-6, 11-dihydrodibenz [b, e] oxepin-2-acetic acid and a 3-dimethylaminopropyltriphenylphosphonium halide in the presence of a base, processes for increasing the (Z) / (E) ratio of a diastereomeric mixture containing olopatadine or a salt thereof, processes for preparing 11-oxo-6, 11-dihydrodibenz [b, e] oxepin-2-acetic acid and 3-dimethylaminoρropyltriphenylphosphonium bromide, and a polymorphic form B of olopatadine hydrochloride. |