Electron-rich ligands, Buchwald-Hartwig amination

The Buchwald-Hartwig amination is an exceedingly general method for generating any type of aromatic amine from an aryl halide or aryl sulfonates.1,2 The key feature of this methodology is the use of catalytic palladium modulated by various electron-rich ligands. Strong bases, such as sodium ferf-butoxide, are essential for catalyst turnover. 

Transition-metal-catalyzed synthesis of poly(arylene)s via carbon-carbon coupling reactions was started by Yamamoto et al. three decades ago [52,53] since then various carbon-carbon bond formation processes with transition-metal catalysts have been applied to polycondensation [54-57]. In recent years, Buchwald et al. and Hartwig et al. developed Pd-catalyzed amination and etherification of aromatic halides by using bulky, electron-rich phosphine ligands [58-60], and this chemistry has been applied to polycondensation for... 

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