SUBSTITUTED BENZOTHIAZINE DERIVATIVE

PURPOSE: To obtain a new derivative having a strong serotonin 2-blocking action and useful for medicines for treating circulatory diseases such as ischemic cardiac diseases, cerebral ascular disorders, and peripheral circulatory disorders. CONSTITUTION: A derivative (salt) of formula I Z is a group of formula II, a group of formula II [R , R are each a (substituted) alkyl, etc.], etc.; Q1 , Q2 are each OH, a halogen, a (substituted) alkyl, etc.; Y is CH, C=, N; m is 0, 1; n is 1-3; E1 , E2 are each H, a lower alkyl; D is a (substituted) aromatic hydrocarbon group, etc.; A is a (substituted) alkylene, etc.; B is O, S, etc.}. For example, 2- 2-[4-(4-fluorophenyl)piperazin-1-yl]ethyl}-5-methoxy-3,4-dihydro-2 H-1,2-benzothiazine-4-one-1,1-dioxide-ethylene-acetal. The derivative is obtained e.g. by allowing a compound of formula IV to act on a nitrogen-containing compound (salt) of formula IV.