[Synthesis of benzofuran derivatives with H2 antagonist activity]

N-[2-(7-Dimethylaminomethyl-5-methyl-2-benzofuranmethylthio)ethyl]-N'-methyl-2-nitro-1,1-ethenediamine (III) and N-cyano-N'-[2-(7-dimethylaminomethyl-5-methyl-2-benzofuranmethylthio)ethyl]-N"-methylguanidine (IV) were synthesized. The direct transformation of 2,2-dicarbethoxy-3-hydroxy-5-methyl-7-dimethylaminomethylcoumaran (VII) and of 2,2-dicarbethoxy-3-hydroxycoumaran (XVI) to the corresponding ethyl 2-benzofurancarboxylates (IX) and (XV) is also reported. A mechanism for this reaction is proposed. Compounds (III) and (IV) showed hystamine H2 receptor antagonist activity, but were less potent than cimetidine and ranitidine.