The observation suggests that the L5-ligated palladium catalyst has a limited lifetime in the catalytic amination of haloarenes with 2a. The ligands bearing a di(tert-butyl)phosphino group, Q-Phos, [5a] cBRIDP, [¹4] cataCXium ® A, [¹5] and (t-Bu) 3 P, [4] [¹6] were found to enable sterically congested 2a to couple with aryl bromide with high efficiency (entries 9-12). In particular, the (t-Bu) 3 P-palladium catalyst successfully produced 3a in 86% yield at three hours.
