KF/Al2O3: an efficient solid heterogeneous base catalyst in one-pot synthesis of benzimidazoles and bis-benzimidazoles at room temperature

KF/Al2O3 is an efficient solid heterogeneous base catalyst in the one-pot synthesis of 2-substituted benzimidazoles and 2,2'-disubstituted bis-benzimidazoles from 1,2-phenylenediamines or 3,3'-diaminobenzidines and acid chlorides, anhydrides, and esters at room temperature.