Ring Transformations of Semicyclic 1,3-Dicarbonyl Heteroanalogs; I. Synthesis of Semicyclic N-Acyl- and N-(Aminocarbonyl)amidine Derivatives and Their Ring Transformation to 5-(ω-Aminoalkyl)-1,2,4-triazoles

The semicyclic N-(thioacyl)- or N-(aminothiocarbonyl)amidines 11 are readily available through reaction of O-methyllactims 9 or in situ generated lactam acetales 10 with aminothiocarbonyl compounds 7 or with carboxamides or ureas 8 and sulfurization of the resultant semicyclic N-acyl- or N-(aminocarbonyl)amidines 12 with P₄S₁₀. The semicyclic N-(thioacyl)- or N-(aminothiocarbonyl)amidines 11 are converted into the S-alkylation products 13. Reaction of 13 with hydrazines gives rise to ring transformation resulting in 5-(ω-aminoalkyl)-1,2,4-triazoles 17. The same products 17 can be obtained by treating semicyclic N-acyl-or N-(aminocarbonyl)amidines 12 first with POCl₃ and then with hydrazines. Similarly, reaction of the N-phenyl-N′-(thiazolidin-2-yliden) thiourea (20) with methyl iodide and hydrazine yields 3-(2-mercaptoethylamino) -5-(phenylamino)-1,2,4-triazole (22).