Facile synthesis and coupling of functionalized isomeric biquinolines

A simple route toward functionalized biquinolines, namely 8,5'-dibromo-5,8'-biquinoline 1 and 5,5'-dibromo-8,8'-biquinoline 2, was developed using Skraup syntheses. Both the dibromo compounds undergo facile Suzuki coupling to afford fluorene-coupled products 3 and 4, respectively, an important transformation in designing conjugated materials based on these cores. X-ray structural analyses of 1 and 4 provide insight into the mode of packing within materials containing these units.