The TS11-3h showed the lowest G # (18.1 kcal/mol), with a wide difference compared to the energy of the sigmatropic reaction. This indicate, the prototropic cascade reaction could be much faster than sigmatropic one, explaining that only the prototropic product 7h was obtained starting from the 1h. Interestingly, a good linear correlation (R 2 =0.88) between the experimental log k and G # of the abstraction of the proton was found (See Figure ). Experimental k values were extracted from ref [29]. G # is the calculated activation free energy of TS11-3x.