Synthesis of substituted 8-methoxyquinolines by regioselective bromine-lithium exchange of 5,7-dihalo-8-methoxyquinolines and 7-bromo-8-methoxyquinoline

Article abstract of DOI:10.1055/s-1995-4053

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 the 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 the 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.