| abstract |
The present invention relates to a process for the preparation of olopatadine and, more particularly, to an improved method of synthesizing olopatadine which comprises reacting a dibenz [b,e] oxepin -1 1- one derivative of formula (III) and a suitable reagent under Witting condition, and to the intermediate l l -[(Z)-3-(dimethylamino)-propylidene] -6- l l -dihvdrodibenz[b,e]-oxepin-2-acet- amide p-toluensulfonate salt. |