Xiaofeng Rao

A highly efficient and aerobic protocol for the synthesis of N-heteroaryl substituted 9-arylcarbazolyl derivatives via a palladium-catalyzed ligand-free Suzuki reaction

A palladium-catalyzed aerobic and ligand-free Suzuki reaction in aqueous ethanol has been developed for the synthesis of N-heteroaryl substituted 9-arylcarbazolyl derivatives. A number of N-heteroaryl halides, namely 2-halogenated pyridines, 2-bromoquinoline, 5-bromopyrimidine and 2-chloropyrazine, were coupled with 4-(9H-carbazol-9-yl)phenylboronic acid (CPBA) or 9-phenyl-9H-carbazol-3-ylboronic acid (PCBA) efficiently to afford good to excellent yields in a short reaction time. Moreover, the catalytic system of Pd(OAc)(2)-EtOH/H(2)O-K(2)CO(3) was successfully extended to the cross-couplings of N-heteroaryl halides with various arylboronic acids. The results demonstrated that the cross-coupling reaction in the present protocol was promoted by oxygen.

Palladium-catalyzed ligand-free and aqueous Suzuki reaction for the construction of (hetero)aryl-substituted triphenylamine derivatives

This paper reports an efficient synthesis of triphenylamine (TPA) derivatives via a palladium-catalyzed Suzuki reaction of (hetero)aryl halides with 4-(diphenylamino)phenylboronic acid (DPBA) in aqueous ethanol under aerobic and ligand-free conditions. Heteroaryl halides, namely pyridyl bromides, quinolyl bromides, pyrimidinyl bromides, 2-chloropyrazine and sulfur-containing heteroaryl bromides, could react smoothly with DPBA, affording good to excellent yields under mild conditions. In addition, aryl bromides were also successfully employed in the cross-couplings with DPBA and furnished the products in high yields at room temperature. The cross-coupling of 4-bromobenzonitrile with DPBA gave the desired product in a quantitative yield within 2 min, resulting in a TOF up to 5820 h−1.

Pd/C-catalyzed ligand-free and aerobic Suzuki reaction in water

Abstract A general and efficient catalytic system for Pd/C-catalyzed ligand-free aerobic Suzuki cross-coupling reactions was developed. The reaction tolerated a wide range of aryl bromides with a hydrophilic group or a hydrophobic group without any additives in water. Moreover, the catalytic system was successfully extended to the cross-couplings of heteroaryl halides with various arylboronic acids. The Pd/C catalyst could be reuse three times without significant loss of catalytic activity.