A rapid synthesis of asymmetric alkyl- and aryl-2,9-disubstitued 1,10-phenanthrolines

The finding that alkyl- and aryllithium reagents add almost instantly to the N–C2/C9 bond of 1,10-phenanthrolines led us to the development of a reaction scheme where the C2 and C9 positions of 1,10-phenanthroline can be functionalized by two different alkyl or aryl groups in a one-pot reaction. Furthermore, the total synthetic and work-up time needed for the entire transformation from unsubstituted 1,10-phenanthrolines into asymmetric 2,9-disubstituted 1,10-phenanthrolines was under 2 h and produced very high yields.