NEW MATERIAL:The 2-(4-lower alkoxyphenyl)-3-substituted-sulfonyloxy-5-dialkyaminoalkyl-2,3-dihydro-1,5-benzothiazepin-4(5H)-one of formula I [R1 is lower alkyl; R2 is lower alkyl or phenyl which may have substituent group (lower alkyl or nitro); n is 1W5] and its acid addition salt.

EXAMPLE: dt-2-( 4-Methoxyphenyl )-3-methanesulfonyloxy-5-( 2-dimethylaminoethyl) -cis-2,3-dihydro-1,5-benzothiazepin-4(5H)-one.

USE: It has central nervous system controllin, antiarrhythmic, local anesthesic, analgesic, anti-inflammatory, and diuretic activities, etc., and is useful as a drug.

PREPARATION: The compound of formula I can be prepared by reacting the compound of formula II with a substituted sulfonyl halide.