Pericyclic Reactions: Woodward–Hoffmann Rules Made Usable
Organic Chemistry · Pericyclic Pericyclic Reactions: Woodward–Hoffmann Rules Made Usable Pericyclic questions look intimidating and are actually among the most predictable on the paper, because the outcome follows from a rule table rather than from mechanism reasoning. BSc & MSc · Organic Chemistry · Concept The short answer: Count the electrons involved, note whether the reaction is thermal or photochemical, and read off the allowed mode. For electrocyclic reactions, 4n electrons go conrotatory under heat and disrotatory under light; 4n+2 electrons do the reverse. Everything else in the topic is an application of that pattern. What makes a reaction pericyclic…