Reply to the “Comment on ‘Intramolecular Proton-Coupled Hydride Transfers with Relatively Low Activation Barriers’”

We thank Martinelli and Richter for their interest in our work and for their insightful analysis of the nature of Generalized Atomic Polar Tensor (GAPT) charges. We agree with their central point that GAPT is a dynamic property derived from dipole derivatives, which is distinct from the various static charge models derived directly from the electronic wave function¹. As Martinelli and Richter correctly state, this discussion does not affect the primary findings of the original paper. Our central finding, which is supported by high-level CCSD(T)/CBS calculations, is the identification of a novel concerted intramolecular proton-coupled hydride transfer (PCHT) mechanism that proceeds with remarkably low activation barrier heights². The original work proceeds to show that the barrier height for the PCHT reaction strongly depends on the length of the alkyl chain connecting the hydroxyl and carbonyl functional groups. This reduction in the reaction barrier heights is rationalized by a significant decrease in the ring strain energy in the cyclic transition structures (TSs).