Synthesis of condensed heterocyclo [n,m-b] quinazolines

ABSTRACT

Condensation of the cyclic imidoyl chlorides; namely, 2-chlorobenzothiazole, 2-chloroquinoline, 2-chloro-4-methylquinoline, 2-chloropyridine and 2-chloro-3-methylquinoxaline with ethyl anthranilate afforded the corresponding 2-[2-ethoxycarbonylphenyl] aminoheterocycles IIIa-f. The products underwent cyclocondensation to the heterocycloquinazolines IVg-i upon heating above their melting points. Condensation of ethyl anthranilate with 2-chloro-4-arylphthalazines directly gave the corresponding quinazolinophthalazines. Attempted isolation of the cyclic intermediates was unsuccessful. The relatively less reactive 2-mercaptobenzimidazole underwent condensation with ethyl anthranilate only upon fusion at a relatively high temperature [300C] to give benzimidazoquinazoline. The structures of all products were assigned on the basis of elemental analysis, IR and PMR spectra