Classification of Organic Reactions: Similarity of Reactions Based on Changes in the Electronic Features of Oxygen Atoms at the Reaction Sites1

Organic reactions occur as a result of complicated interactions among many factors:  structural and electronic features of reactants, reagents, catalysts, temperature, etc. In this study, organic reactions were automatically classified based on these factors. A dataset of 131 reactions was investigated focusing on the changes of electronic features on the oxygen atoms at the reaction sites by principal component analysis and self-organizing neural networks analyses. Good correlations were found between the similarities in the changes of the electronic features of oxygen atoms of the reaction sites and the similarities in the substructural transformations at the reaction sites as well as with the known reaction types. These results demonstrate that a classification based on changes of electronic features is closely related to the classifications which chemists have been establishing from various points of view. Furthermore, this indicates the possibility for the automatic and systematic classification of a...