Synthesis of benzimidazoles by PIDA-promoted direct C(sp2)-H imidation of N-arylamidines
A metal-free synthesis of diversified benzimidazoles from N-arylamidines through a phenyliodine(III) diacetate (PIDA) promoted intramolecular direct C(sp2)-H imidation has been developed. The reaction proceeds smoothly at 0 °C or ambient temperature to provide the desired products in good to excellent yields. The synthesis of 2-alkyl- or 2-alkyl-fused benzimidazoles, which are generally inaccessible by similar Pd- or Cu-catalyzed approaches, can also be achieved. Copyright
Huang, Jinbo,He, Yimiao,Wang, Yong,Zhu, Qiang
supporting information
p. 13964 - 13967
(2013/01/15)
Palladium-catalyzed intramolecular C(sp2)-H amidination by isonitrile insertion provides direct access to 4-aminoquinazolines from N-arylamidines
An efficient method for the synthesis of 4-amino-2-aryl(alkyl)quinazolines from readily available N-arylamidines and isonitriles via palladium-catalyzed intramolecular aryl C-H amidination by isonitrile insertion has been developed.
Direct imidation to construct 1H-benzo[d]imidazole through Pd II-catalyzed C-H activation promoted by thiourea
A study was conducted to demonstrate the development of a method to construct 1H-benzo[d]immidazole through PdII -catalyzed intermolecular C-H activation starting from N-phenylbenziimidamide. The detailed mechanism investigations indicated that a palladacycle monomer or dimer was the key intermediate for this transformation, demonstrating that thiourea was first used to influence the efficiency of C-H activation. The method was found to construct 1H-benzo[d]immidazole through PdII -catalyzed intermolecular C-H activation extending the substrate scope widely. It also demonstrated the introduction of thiourea (tetramethylthiourea) (TMTU) for the first time as an additive to promote the efficiency of PdII catalysis for the direct C-H transformation. N-phenylbenziimidamide was also readily synthesized through the addition of aniline to benzonitrile according to the method to conduct the investigations.