OPTICALLY ACTIVE PIPERIDINE DERIVATIVE ACID ADDITION SALT AND ITS PRODUCTION

PROBLEM TO BE SOLVED: To obtain the subject new compound excellent in antihistaminic activity and antiallergic activity, having a few hygroscopic property, excellent in physicochemical property and useful as a medicine. SOLUTION: This new compound is benzenesulfonic acid salt of a compound represented by formula I. The new compound is preferably obtained by subjecting 1 mol compound of formula I to salt formation reaction with 0.9-1.2 mol benzenesulfonic acid in a solvent such as ethyl acetate, preferably at 10-35 deg.C. The solvent is preferably used in an amount of 1 to 10 L based on 1 mol compound of formula I. The temperature at salt deposition is preferably -10 to 15 deg.C. The compound of formula I is obtained by reacting an optically active (S)-4-[(4-chlorophenyl) (2-pyridyl)methoxy]piperidin with a compound of formula II (W is an eleiminable group; R is a lower alkyl) (e.g. ethyl 4- bromobutanoate) in an inert solvent in the presence of a base and then subjecting the resultant compound of formula III to hydrolysis reaction.