Development of Pyridine-2,6-dicarboxamide Ligands for Copper Catalyzed Aryl Amination

Abstract

Catalysis is well-established field for building up the complex molecules because it brings the multistep reaction to a single step with increased selectivity and functional group tolerance, which otherwise could not be achieved by using conventional methods. Discovery of ligated catalysis have brought about the revolution in transition metal catalyzed C-C and C-X bond formation. To contribute towards these reactions, pyridine-2,6-dicarboxamide ligands have been developed. Among four ligands synthesized, N,N,N’,N’-tetramethylpyridine-2,6-dicarboxamide is found to be good promoter in building the C-X bond. Arylation of anilines bearing electron donating groups can be carried out using these ligands. Arylation of anilines yielded 50-55% product. Aliphatic amines and N-substituted anilines are found to be reluctant towards arylation reactions and gave no product in case of former while traces in case of latter. N-arylation of heterocycles gave good to excellent yields. Arylation of indole yielded 99% product and substituted benzimidazole 97% product. O-arylation of phenols are also carried out getting 80% yields.