As discussed above, tunneling is known to play a dominant role in several tautomerization reactions. We therefore ventured to explore the tunneling rates in the two water-catalyzed tautomerizations of 1-5 systems. Except for 1H,H, our computed semiclassical kSC rates show that the reaction should be feasible under experimental conditions at 298.15 K (see Table ). However, as discussed below, the assistance of tunneling is predicted to significantly accelerate the reaction rates for all the studied systems.