Pteridines, XCIII. Reactions of 6-Chloro-, 7 -Chloro- and 6,7-Dichloro-1,3-dimethyllumazines with N-Nucleophiles

Abstract

The reactivity of 6-, (18) and 7-monochloro (1) as well as 6, 7-dichloro-1 ,3-dimethyllumazine (19) towards a broad variety of primary and secondary amines has been investigated. Nucleophilic displacements take place very easily at C-7 (2 - 8), whereas substitution at C-6 (12 - 17) required more severe reaction conditions. Selective displacements can be achieved with 19 under mild conditions to give 20-41 , since introduction of a 7-subst. amino function decreases the reactivity of the 6-chloro atom even further. Prolonged heating at elevated temperature led to various 6,7-di-subst. amino derivatives (42-51). Heating of 7-subst. amino-6- chloro-1 ,3-dimethyllumazines (27, 29, 31, 33) with morpholine proceeded with an anomalous dehalogenation of unknown mechanism to form the corresponding 6 C - H derivatives (4, 9, 19, 11). The newly synthesized compounds have been characterized by elemental analysis, UV- and NMR-spectra.