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.

Question

Draw the complete mechanism for the reaction below. Please include appropriate arrows, intermediates, and formal charges.

Answer 1

Question

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.

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