A Highly Regioselective Sonogashira Coupling as a Key Step in the Preparation of the First Phenanthroline with Two Diverse Reactive Groups in 3,8-Positions

The preparation of 3,8-unsymmetric phenanthrolines is described. Desymmetrization of 3,8-dibromophenanthroline was achieved after monoarylation followed by regioselective Pd-catalyzed monoalkynylation that was controlled by the methoxy group of the dimethoxyphenyl substituent.