Syntheses of Pyridazine Derivatives. I. Structure of 3-Mercapto- 6(1H)-pyridazinethione and its Addition to Some Unsaturated Systems

The structure of 3-mercapto-6(1H)-pyrida:dnethione is discussed. On the basts of spectroscopic evidence and pK values, structure (I) is proposed, with an important contTibution of the dipolar character. Some addition reactions on unsaturated systems, e.g. acrylonitrile, ethyl acrylate and cyclopentadiene, were performed affording invariably S-alkylated derivatives

Some Derivatives of Perhydro-imidazo(l,5-a)pyridine and Perhydro-pyrrolo(l,2-c)imidazole

Some derivatives o:t perhydro-imidazo(l,5-a)pyridine and -pyrrolo(l,2-c)imidazole were synthesized and a new synthetic route was also developed. This synthesis and other chemical and spectroscopical evidence indicates the structure for these substances with the exo-cyclic sulphur

Synthesis of Isomeric 3-Aminopyridopyrimidin-4(3H)ones

It could be established that the reaction between hydrazine and enamines, formed from ethyl 2(or 3)-aminopyridine-3(or 2)carboxylates and diethyl ethoxymethylenemalonate or ethyl ethoxymethylenecyanoacetate, afforded 3-aminopyrido(2,3-d)pyrimidin- 4(3H)one or 3-aminopyrido(3,2-d)pyrimidin-4(3H)one, respectively. Similarly, these aminopyridinecarboxylates condense with N,N- dimethylformamide dimethylacetal and react further with hydrazine to give the same bicyclic compounds

Contribution to the Structm·e of 2,5-Dimercapto-1,3,4-thiadiazole and Related Compounds

The structure of 2,5 - dimercapto-1,3,4-thiadiazole and some derivatives was studied from the dependence of UV spectra on pH and H 0 and a monomercapto monodipolar structure is proposed. Evidence was presented tha t addition reactions of 2,5-dimercapto- 1 ,3,4-thiadiazoles on unsaturated systems proceed with the formation of S-akyla ted derivatives involving thus the mercapto group

Structure of Some s-Triazoloquinazolinones

Reaction between 3-amino-1,2,4-triazole and 2-carbethoxycyclohexanone can theoretically afford the tricyclic product of the types IV-VII. It was established that the product has structure V and similarly for other cyclization products structures are proposed

Synthesis of Pyridazine Derivatives. XVII. Some Reactions on 2-Phenylimidazo(1,2-b )pyridazines

The behavior of 2-phenylimidazo(l,2-b)pyridazines in some electrophilic and nucleophilic subs.titution reactions has been examined. It has been found that besides the expected electrophilic substitution at position 3 of the imidazo-(1,2-b)pyridazine ring, upon nitration a second nitro group enters the phenyl group on para position as evident from an examination of the NMR spectrum. Hydrazinolysis of a 3,6-dihalo derivative proceeded preferentially at position 6

Syntheses of Pyridazine Derivatives. I. Structure of 3-Mercapto- 6(1H)-pyridazinethione and its Addition to Some Unsaturated Systems

The structure of 3-mercapto-6(1H)-pyrida:dnethione is discussed. On the basts of spectroscopic evidence and pK values, structure (I) is proposed, with an important contTibution of the dipolar character. Some addition reactions on unsaturated systems, e.g. acrylonitrile, ethyl acrylate and cyclopentadiene, were performed affording invariably S-alkylated derivatives

Structure of Some s-Triazoloquinazolinones

Reaction between 3-amino-1,2,4-triazole and 2-carbethoxycyclohexanone can theoretically afford the tricyclic product of the types IV-VII. It was established that the product has structure V and similarly for other cyclization products structures are proposed

Contribution to the Structm·e of 2,5-Dimercapto-1,3,4-thiadiazole and Related Compounds

The structure of 2,5 - dimercapto-1,3,4-thiadiazole and some derivatives was studied from the dependence of UV spectra on pH and H 0 and a monomercapto monodipolar structure is proposed. Evidence was presented tha t addition reactions of 2,5-dimercapto- 1 ,3,4-thiadiazoles on unsaturated systems proceed with the formation of S-akyla ted derivatives involving thus the mercapto group