Local reactivity descriptors of the important atoms in chelotropic reactions provide insight into their global variants along the reaction path

Abstract

Chelotropic reactions are widely used in organic synthesis. These reactions are of the pericyclic type where a π bond and a lone pair are transformed into a pair of sigma bonds; with both sigma bonds added to the same atom. This work presents an analysis of several representative chelotropic reactions. To study the reaction path, we have divided it into two parts, from the reactants to the transition state and from the transition state to the products which has allowed us to compare the behavior of the reactants in these two ranges of the path. To perform the analysis, global reactivity descriptors based on the conceptual‐density functional theory (DFT), such as electrophilicity and global softness, have been calculated. To analyze these descriptors, the corresponding local descriptors have been used. A model based on Sanderson's principle (electronegativity equalization principle), developed previously, has been used to calculate the local reactivity descriptors (atomic). The statistical methodology of multiple regression analysis has been used to determine which local variables are the most relevant for the global parameter under study (softness, and electrophilicity), also the principal component analysis has been used as a guide to estimate the number of variables to take into account in the analysis, finally this has led us to important correlations between global and local parameters which has allowed us to analyze the reactions of the study. Transition states of the reactions are aromatic as obtained from the nucleus independent chemical shift (NICS) and gauge including magnetically induced ring current (GIMIC) analysis.

CO2 reduction using aluminum hydride: Generation of in‐situ frustrated Lewis pairs and small molecule activation therein

“…Using the unified philicity concept, the concept of multiphilic descriptor 69,70 was proposed to account for the nucleophilic and electrophilic attack. The multiphilic descriptor for the nucleophilic attack is defined as the difference between condensed‐to‐atom nucleophilic and electrophilic philicity functions 71 . When considering the reverse difference, this can also be used for the electrophilic attack. …”

Unraveling Reactivity Pathways: Dihydrogen Activation and Hydrogenation of Multiple Bonds by Pyramidalized Boron‐Based Frustrated Lewis Pairs

“…This suggests that the N center is more likely to act as a nucleophilic center or be susceptible to electrophilic attack. [90][91][92] Conversely, for the B center, the ω + k (orange) value (0.405) is higher than the ω + k (green) value (0.025), suggesting that the B center can exhibit either electrophilic behavior or susceptibility to nucleophilic attack. Similarly, in all the examined B/E-FLP, the corresponding B centers will act as electrophilic centers.…”