NEW MATERIAL:A 2-guanidinothiazoline derivative shown by the formula I (R is H or lower alkyl; X is halogen) and its acid addition salt. EXAMPLE:N''-[4-(Chloromethyl)-45-dihydro-4-hydroxy-2-thiazolyl]-guani dine hydrochloride. USE:A compound useful as an H2-antagonist or an inhibitor against secretion of acid in the stomach useful as an intermediate for preparing especially famotidine and tiotidine. PREPARATION:An amidinothiourea shown by the formula II is reacted with a corresponding amount of ...

Novel 2-guanidinothiazoline compounds of the general formulawherein R represents a hydrogen atom or a lower alkyl group and X represents a halogen atom and the acid addition salts thereof; they are important intermediate compounds for preparing famotidine and thiotidine which are medicaments useful f as gastric acid secretion inhibitors.