One-step vs. Stepwise Reaction Mechanisms in Pericyclic Reactions

4 One-Step vs. Stepwise Reaction Mechanisms in Pericyclic Reactions 

The basic idea of the above criterion is very simple and consists in the qualitative comparison of the relative ease of selected idealized reaction paths corresponding in the More O Fenall diagrams to purely synchronous (concerted) and purely assynchronous (stepwise) reaction paths (90). 

The relative ease of these selected reaction paths is qualitatively estimated by the comparison of similarity indices, characterizing the extent of electron reorganization in all individual reaction steps. (Eq. 91). 

Since in the case of ideally synchronous conceited process R - P the mutual relation of similarity index and the extent of electron reorganization was already discussed in previous chapter (6), it is necessary to specify only the characterization of the electron reorganization in the case of nonconcerted stepwise process. For this purpose we proposed a simple model [124], allowing to characterize the extent of 

The derivation of this expression is based on the following idea Let us suppose for a moment that the reaction steps forming the stepwise reaction scheme are completely independent. In this case, the total extent of electron reorganization would be given 

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