Rolf Wessel

Umwandlung von 1,3,4-Thiadiazolinen in 1,2,4-Triazole durchDimroth-Umlagerung

On heating compounds4 a-f in alcohols, Dimroth rearrangement occurs to yield5 a-f, which can be methylated with dimethyl sulphate to the S-methyl derivatives6 a, b, d, f. 6 a, b can be cyclized with one equivalent of aqueous hydrogen bromide to9 a, b. 9 a could not be prepared by reacting 3-methylthio-5-amino-1,2,4-triazole (10) with phenacyl bromide.

Über einige Umsetzungen von 2,5-Diamino- sowie 2-Amino-1,3,4-thiadiazolen mit α-Halogenketonen zu Imidazo[2,1-b]-1,3,4-thiadiazolen

Abstract2,5-Diamino-1,3,4-thiadiazole (1) reacts with α-halogencarbonyl compounds to 2-imino-3-phenacyl(acetonyl)-5-amino-1,3,4-thiadiazolines (3) which easily can be cyclised to 2-amino-6-aryl (alkyl)-imidazo[2,1-b]-1,3,4-thiadiazoles (4), the structure of which was proofed.On the basis of the amino function in position 2 these substances were able to form easilySchiff bases (5, 6, 7). Their semicyclic amidine system did not allow as yet to integraet it in a third ring system.

Zur Synthese von Imidazo(2,1-b)-1,3,4-thiadiazolo(3,2-a)-pyrimidonen-(6)

Abstract2-Amino-6-aryl-imidazo(2,1-b)-1,3,4-thiadiazoles (1 a-f) were condensed with 1,3-ketocarboxylates e. g. ethyl-butyroacetate, ethyl-benzoylacetate, 4-nitrobenzoylacetate or ethyl-cyclopentanone(2)-carboxylate and ethyl-cyclohexanone(2)-carboxylate directly to imidazo(2,1-b)-1,3,4-thiadiazolo(3,2-a) pyrimidones-(6) (4 a-f, 5 a-f, 6 d, e, 7 a-f, 8 a, d).