Chapter 30.SE, Problem 22AP

Interpretation Introduction

Interpretation:

The manner of ring closure-conrotatory or disrotatory- for both thermal and photochemical cyclization of (2E,4Z,6Z,8E)-2,4,6,8-decatetraene in to 7,8-dimethyl-1,3,5-cyclooctatriene indicating the stereochemistry is to be stated.

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.

To predict:

The manner of ring closure-conrotatory or disrotatory- for both thermal and photochemical cyclization of (2E,4Z,6Z,8E)-2,4,6,8-decatetraene in to 7,8-dimethyl-1,3,5-cyclooctatriene.

The stereochemistry of the product.