SYNTHESIS OF SUBSTITUTED 8-METHOXYQUINOLINES BY REGIOSELECTIVE BROMINE-LITHIUM EXCHANGE OF 5,7-DIHALO-8-METHOXYQUINOLINES AND 7-BROMO-8-METHOXYQUINOLINE

Reaction of phenyllithium with 7-bromo-8-methoxyquinoline, 5,7-dibromo -8-methoxyquinoline and 5,7-diiodo-8-methoxyquinoline has been studied . Thus, bromine-lithium exchange of 7-bromo-8-methoxyquinoline gave th e 7-lithio-8-methoxyquinoline which reacted with various electrophiles to afford 7-substituted 8-methoxyquinolines 3a-e. The same procedure was also applied to 5,7-dibromo-8-methoxyquinoline, which because of t he high regioselectivity of the reaction, led to 7-substituted 5-bromo -8-methoxyquinolines 4a-f; one of them was used for the preparation of a pyridopyranoquinoline.