| abstract |
Novel heterocyclic compounds of the formula: ##STR1## wherein either X is --CR 1 R 2 -- and Y is oxygen, sulphur or --NR 3 --, wherein R 1 , R 2 and R 3 , which may be the same or different, each is hydrogen or alkyl of up to 4 carbon atoms; or X is oxygen, sulphur or --NH-- and Y is --CH 2 --; wherein R 4 and R 5 , which may be the same or different, each is hydrogen, cyano, nitro, amino or hydroxy, or alkylthio of up to 4 carbon atoms, or has various other meanings defined in claim 1, provided that R 4 and R 5 are not both hydrogen; or wherein R 4 and R 5 are joined together such that with the benzene ring A they form a benzheterocyclic ring as defined in claim 1; and therein the benzene ring A may optionally bear one or more further substituents; or a salt thereof where appropriate. n These compounds possess cardiotonic properties, and some of them possess peripheral vasodilator properties, and they are useful for the treatment of acute or chronic heart failure. Representative of the compounds is N,N-dimethyl-p-(5,6-dihydro-5-oxo-4H-1,3,4-thiadiazin-2-yl)benzamide. Also disclosed are processes for the manufacture of the compounds and pharmaceutical compositions containing them. |