Electrocyclic reactions are a type of organic reaction where a conjugated system undergoes a ring closure or ring opening in response to heat or light. These reactions typically involve the formation or breaking of a sigma bond while maintaining a cyclic structure. The process is governed by the Woodward-Hoffmann rules, which predict the stereochemistry and feasibility of the reaction based on the electronic configuration of the reactants. In an electrocyclic reaction, the transition state can be either conrotatory or disrotatory, depending on the number of π electrons involved. For example, a six-membered ring can form from a linear conjugated diene when subjected to heat, resulting in a specific stereochemical outcome. These reactions are important in synthetic organic chemistry for constructing complex molecular architectures.