According to Zhang, Yang and Zhao , authors of the study under consideration, the control of regioselectivity with 3,4-disubstituted phenols is still a significant and challenging work, which remains unsolved. So, they proposed to develop a selective method for C-H ortho-cyanation promoted by Lewis acid in 3-substituted and 3,4-disubstituted phenols in two different ortho positions, as can be seen in Figure . After an initial step for optimizing reaction conditions, in which it was stablished that the reaction would be best conducted under a combination of both AlCl3 and BF3 • OEt2 as Lewis acid catalysts and CH3SCN as cyan donor, they explored the scope of its reaction through the cyanation of 3-substituted and 3,4-disubstituted phenols to afford a wide range of the corresponding 2-hydroxybenzonitriles in good or excellent yields and with enhanced regioselectivity. and Zhao .