Non-C₂-Symmetric Bis-Benzimidazolium Salt Applied in the Synthesis of Sterically Hindered Biaryls

A novel non-C₂-symmetric bis-benzimidazolium salt derived from (±)-valinol has been prepared by a simple and straightforward process in good yield. The structure of bis-benzimidazolium salt provided a bulky steric group on the ethylene bridge; which facilitates the catalytic efficacy in the C(sp²)-C(sp²) formation. Its catalytic activity in Suzuki-Miyaura cross-coupling reaction of unactivated aryl chlorides has been found to have high efficacy in 1 mol% Pd loading. This protocol demonstrated the potential on the synthesis of sterically hindered biaryls.