M. Kocevar

Reactions of some diazoazoles with reactive methylene and other groups

Abstract Reactions of some heteroaromatic diazo compounds with 1,3-dicarbonyl compounds, amines and thiophenol to give bi- and tricyclic heterocycles are studied. Decomposition of heterocyclic diazo compounds, triazenes and related compounds are investigated.

Neighbouring group participation in formation of condensed azines. Formation of pyrazolo(3,4-b)pyrazines, isoxazolo(4,5-b)pyrazines and isothiazolo(5,4-b)pyridine

Pyrazine- and pyridinecarboxamidoximes with an amino, potentially tautomeric hydroxy or mercapto group inortho position could be transformed in the appropriate condensed azines. In this manner, representatives of pyrazolo(3,4-b)pyrazine, isoxazolo(4,5-b)pyrazine and isothiazolo(5,4-b)pyridine ring system were synthesized and some transformations investigated.ZusammenfassungMit einer Amino-, potentiell tautomerer Hydroxy- oder Mercaptogruppe wurdenortho-substituierte Pyrazin- oder Pyridincarboxamidoxime in die entsprechenden kondensierten Azine umgewandelt. Auf diese Weise wurden Derivate des Pyrazolo(3,4-b)pyrazin, des Isoxazolo(4,5-b)pyrazin und Isothiazolo(5,4-b)pyridin dargestellt und einige Umwandlungen studiert.

Ring transformations of some 4-aminopteridine 3-oxides and derivatives

Syntheses of 4-aminopteridine 3-oxides are described. The pyrimidine part undergoes transformations with various reagents to give 4-hydroxyaminopteridines, substituted pyrazines, or substituted 1,2,4-oxadiazolyl- pyrazines. s-Triazolo(l,5-a)pyrazines can be prepared from the 1,2,4-oxadiazolylpyrazines. The ring opening of the pyrimidine part of pteridines proceeds either by a C2-N3 or N3-C4 bond cleavage.