Collect. Czech. Chem. Commun. 1994, 59, 75-88

The Least Motion Principle, Concertedness and the Mechanisms of Pericyclic Reactions. A Similarity Approach

Robert Ponec and Martin Strnad

Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 165 02 Prague 6-Suchdol, Czech Republic


The recently proposed topological criterion of concertedness was complemented by a procedure allowing the variational determination of reaction paths characterizing the detailed course of bonding reorganization in modified More O'Ferrall diagrams. The proposed approach, allowing the simple unequivocal classification of reaction mechanisms is demonstrated with examples of several selected pericyclic reactions, both forbidden and allowed. The mechanistic conclusions obtained are in qualitative agreement with the predictions based on expectations from Woodward-Hoffmann rules and independent theoretical calculations.