The Application of Pd- and Cu-Catalyzed Carbon-Nitrogen Bond Formation to Heterocycle Synthesis

by Zheng, Nan; Tsang, W. C. Peter; Anderson, Kevin W.; Munday, Rachel; Brasche, Gordon; Huang, Xiaohua; Nguyen, Hanh; Buchwald, Stephen L.

Two complementary catalytic methods will be described for the prepn. of N- aryl and alkyl benzimidazoles in regiochem. pure form starting from ortho-halo anilides or anilines. The first method employing Pd2(dba)3 and XPhos or RuPhos permits efficient synthesis of N-aryl benzimidazoles and tolerates a wide range of functional groups. The second method utilizing CuI and trans-N, N'-dimethyl-1,2-cyclohexanediamine allows the prepn. of N-alkyl benzimidazoles in good to excellent yields. Addnl., a catalytic method using tandem Pd-catalyzed C-H functionalization and carbon-nitrogen bond formation will be discussed for the synthesis of carbazoles.