Chapter 30.SE, Problem 21AP

Interpretation Introduction

Interpretation:

Whether the cyclization and formation of a bicyclic product when (1Z,3Z,5Z)- 1,3,5-cyclononatriene is heated at 100ºC takes place in conrotatory or disrotatory manner is to be identified. Further the stereochemical relationship of the two hydrogens at the ring junction, cis or trans 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 identify:

Whether the cyclization and formation of a bicyclic product when (1Z,3Z,5Z)- 1,3,5-cyclononatriene is heated at 100ºC takes place in conrotatory or disrotatory manner.

To state:

The stereochemical relationship of the two hydrogens at the ring junction, cis or trans.