Chapter 30.SE, Problem 20AP

Interpretation Introduction

Interpretation:

Whether the reaction shown will take place in conrotatory or disrotatory manner is to be stated. The stereochemistry of the cyclobutene product is to be given and explained.

Concept introduction:

An electrocyclic reaction involves the cyclization of a conjugated acyclic system. These reactions are reversible and are highly stereospecific.

In elecrocyclic reactions involving even number of electron pairs, a thermal reaction occurs in conrotatory manner and a photochemical reaction occurs in disrotatory manner.

In elecrocyclic reactions involving odd number of electron pairs, a thermal reaction occurs in disrotatory manner and a photochemical reaction occurs in conrotatory manner.