NEW MATERIAL: A compd. represented by formula I [wherein Alk is a 1-6C (hydroxy)alkylene, Ar is 5,6,7,8-tetrahydro-1-naphthalenyl or phenyl, R is H or a 1-6C alkyl, X, Y and Z are each O or S, m is 0-3 and n is 0-5], its salt and its isomer.

EXAMPLE: 2-[{[3-(4-acetyl-3-hydroxy-2-propylphenoxy)propyl]thio}methyl-1,4- dithiaspiro[4,4]nonane-7-acetic acid.

USE: Antiallergic drugs and anti-inflammatory agents.

PROCESS: At first, a ketoester compd. represented by formula II (R' is a 1-6C alkyl) is reacted with a compd. represented by formula III to obtain a compd. IV and this compd. is reacted with a compd. represented by formula V in the presence of a org. solvent and potassium carbonate to obtain a compd. represented by formula VI. Subsequently, this compd. is treated with lithium hydroxide to obtain the compd. represented by formula I (wherein X and Z are each S, Y is O, and R is H).