In the prototropic pathway, the TS11-3x has the C 1 -H 1 bond distances increased in the order of the aryl substituent h < g < f < e < d < b, while the H 1 -OMeOH distances decrease in opposite trend. A bcp connecting the H 1 atom and methoxide oxygen (H 1 -OMeO) appeared in TS11-3x, due to the proton abstraction process (Figure ). The values of b at the C 1 -H 1 bcp decrease following the order h < g < f < e < d < b, while at the H 1 -OMeOH bcp those increase in opposite trend.