Original scientific paper

Pteridines, LXXVIII Reactions and Properties of 4-Thiolumazine Derivatives

Herman Lutz ; Fakultat fur Chemie, Universitat Konstanz, Postfach 5560, D-7750, Konstanz/West Germany
Wolfgang Pfleiderer ; Fakultat fur Chemie, Universitat Konstanz, Postfach 5560, D-7750, Konstanz/West Germany

Abstract

The reactivity of the 4-thioxo function towards nucleophiles
in the 1- (X) and 3-methyl- (XI) and 1,3-dhnethyl-6,7-diphenyl-
-4-thiolumazine (XII) series was examined, show ing easy displacements under mild conditions. Special structural and electronical features became obvious with 3-methyl-6,7-diphenyl-4-thiolumazine (XI), which reacted analogously to the corresponding 1,3-dimethyl derivative (XII) with amines to the 4-imino tautomers
(XVIII-XXIV) and with hydrazines to the corresponding 4-hydrazones
(XXVI-XXX). The latter compounds are very light sensitive and react by photooxidation to the corresponding 6,7-diphenyllumazines
(VI-VIlI). Nucleophilic displacement of the sulfur in the 4-thioamide group by alkoxides and under HgBr2 catalysis yielded the unusual 4,4-di-O-alkyl amidacetals (XXXIII- XXXVI). The acetal function is prone to easy substitution by C-H acidic compounds, giving from XXXIV the 4-dicyanomethylen- 1,3-dimethyl-2-oxo-6, 7-diphenyl- tetrahydropteridine (XXXIX). The newly synthesized compounds have been characterized by element ary analysis, lH-NMR and UV spectra based onpKa-values.

Keywords

Hrčak ID:

177590

URI

https://hrcak.srce.hr/177590

Publication date:

16.5.1986.

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