| abstract |
Disclosed is a method wherein (Z)-11-(3- dimethylaminopropylidene)-6,11-dihydrodibenz[b,e]oxepin-2- acetic acid (general name: olopatadine) or an acid addition salt thereof, which is useful as a pharmaceutical product, is produced by processing a dibenzoxepin derivative represented by the formula [I] below with a dehydrating agent for obtaining a mixture of a dibenzoxepin derivative represented by the formula [II] below and a dibenzoxepin derivative represented by the formula [III] below, and then processing the thus-obtained mixture with an acid. (In the formula [I], R1, R2 and R3 independently represent an alkyl group having 1-2 carbon atoms.) (In the formula [II], R1, R2 and R3 are as defined above.) (In the formula [III], R1, R2 and R3 are as defined above.) |