Substituted 3-cyclobutene-1,2-diones, pharmaceutical compositions thereof and methods of use

摘要

Compounds of the formula <IMAGE> wherein R12 is a leaving group, Z is S, O or CH2 and A is a phenyl, furyl, thienyl or pyridyl ring substituted by a <IMAGE> moiety, in which R8 and R9 are various substituents or, when taken together with the nitrogen, may be a specified heterocyclic ring, are intermediates in the preparation of histamine H2-antagonist anti-ulcer agents of the formula <IMAGE> in which R1 and R2 are any of several specified substituents.