Design and synthesis of novel 1,10-phenanthroline derivatives

Abstract

To access functionalized nitrogen ligands, a series of novel 1,10-phenanthroline derivatives 1a~1d were designed and synthesized. Starting from 1-bromoaryl-3-chloroacetone (2) and o-phenylenediamine (3), 4,7-dibromoaryl-1,10-phenanthroline (4) were obtained in up to 64% yield by using a straightforward one-pot method catalyzed by mixed acids. Next, halogen lithium exchange reactions were performed to give 4. Finally, quenching of the reaction mixture with CO2 gave the desired 2,9-dialkyl-4,7-bis(carboxy-aryl)-1,10-phenanthroline derivatives 1 in up to 59% yield. This work provides a simple and convenient route to synthesize new 2,9-alkylated carboxylic acid-functionalized phenanthrolines.