NEW MATERIAL:The titled compound of formula I (R1 and R2 are H or lower alkyl groups; X1 and X2 are H, lower alkyl, lower alkoxy groups, etc.; Y is acid residue).
EXAMPLE: 2, 3-Dihydro-7-methyl-1H, 5H-isothiazolo[ 2, 1-a ][ 2, 1 ]benzoisothiazolium chloride.
USE: A drug for peptic ulcer having a gastric secretion suppressing action and an intermediate for the synthesis of a benzothiazocine-S-oxide compound having the powerful action.
PROCESS: A benzothiazocine-S-oxide compound of formula II is reacted with an acid, e.g. a mineral acid such as hydrochloric, nitric or sulfuric acid, in a solvent, e.g. methanol, at room temperature for 5minW1hr to give the compound of formula I. The resulting compound can be converted into the compound of formula II by treating with a base, e.g. NaOH or KOH.
FUJITA HIROSHI
KOBAYASHI SHINSAKU
