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Pericyclic Reactions: Electrocyclic Reactions

Electrocyclic Reactions: Introduction

From a historical point of view, electrocyclic reactions and their remarkable stereospecificity in particular gave rise to the development of the concept of pericyclic reactions and the Woodward-Hoffmann rules in the early 60s. Electrocyclic reactions are characterized by the fact that a linear conjugated π system cyclizes by forming a σ bond.

Fig.1
Schematic representation of an electrocyclic reaction

As is the case with all pericyclic reactions, electrocyclic reactions pass through an aromatic transition state. The reaction is reversible with ring opening favored in 3- and 4-membered rings (reduction in ring strain).

Fig.2
Examples
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