Woodward-Hoffmann rules general selection rule

The so-called aromaticity rules are chosen for comparison, as they provide a beautiful correspondence with the symmetry-based Woodward-Hoffmann rules. A detailed analysis [92] showed the equivalence of the generalized Woodward-Hoffmann selection rules and the aromaticity-based selection rules for pericyclic reactions. Zimmermann [93] and Dewar [94] have made especially important contributions in this field. 

Generalization of the Woodward-Hoffmann rules for sigmatropic processes leads to the selection rules in Scheme 11.2. ... 

The Generalized Woodward Hoffmann Pericyclic Selection Rules... 

The selection rules for chemical reactions derived by using symmetry arguments show a definite pattern. Woodward and Hoffmann generalized the selection rules on the basis of orbital symmetry considerations applied to a large number of systems [89], Two important observations are summarized here we refer to the literature for further details [90, 91],... 

This type of condensation is of great interest in connection with the Woodward-Hoffmann selection rules for symmetry-allowed concerted suprafacial and antarafacial cycloaddition reactions.284 The generalized rules for cycloaddition of an m- to an n-electron system predict that the concerted supra-supra or antara-antara dimerization is allowed in the excited state (i.e., photochemically) when m + n = 4q, and in the ground state (i.e., thermally) when to + n = 4q + 2, where to and n are the numbers... 

---