NEW MATERIAL:The compound of formula I (R1 is H, halogen, nitro, lower alkyl, or lower alkoxy; R2 is lower alkyl, aralkyl, phenyl, halogenophenyl, nitrophenyl, lower alkylphenyl, etc.; R3 is lower alkylaminoalkyl or morpholinoalkyl), its optical isomer or their acid addition salt.

EXAMPLE: dl-2-(4-Methoxyphenyl)-3-(4-chlorobenzenesulfonyloxy)--5--(2-dimethyla minoethyl)-cis-2,3-dihydro-1,5-benzothiaze-pin--4(5H)-one.

USE: Medicinal drug having calcium antagonistic, central nervous controlling, antiarrhythmic, local anesthetic, analgesic, antiinflammatory, antipyretic, and diuretic activities.

PREPARATION: The compound of formula I can be prepared quantitatively by reacting the compound of formula II or its salt with the compound of formula III (X is halogen) optionally in the presence of a dehydrohalogenation agent.