Potential Histamine H₂‐Receptor Antagonists: Synthesis and Pharmacological Activity of Derivatives Containing Acylamino‐furazan Moieties

Analogues of 3‐amino‐4‐[2‐[(5‐dimethylaminomethyl‐2‐furyl)methylthio] ethylamino]furazan (1) containing carbonyl groups joined to the amino functions linked to the furazan system have been synthetized and investigated for their H₂‐antagonist properties on the isolated guinea pig right atrium. The presence of the carbonyl group lowers the activity in respect to the corresponding leads. The decrease in activity is only by 1‐2 orders of magnitude in the 3‐acylaminofurazan series versus inactivity in the 4‐acylamino isomers and in the diacylated series.