The manner of ring closure-conrotatory or disrotatory- for both thermal and photochemical cyclization of (2E,4Z,6Z,8Z)-2,4,6,8-decatetraene indicating the stereochemistry of the product 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,8Z)-2,4,6,8-decatetraene. To state: The stereochemistry of the product.

Question

Treatment of cyclohexene with iodobenzene under the conditions of the Heck reac- tion might be expected to give 1-phenylcyclohexene. The exclusive product, however, is 3-phenylcyclohexene. Account for the formation of this product. CH3 Pd(OAc), 2 PhạP + CGH;I (CH,CH2),N 3-Phenylcyclohexene (racemic) 1-Phenylcyclohexene (not formed)

Answer 1

Question

Chapter 30.SE, Problem 23AP

Interpretation Introduction

Interpretation:

The manner of ring closure-conrotatory or disrotatory- for both thermal and photochemical cyclization of (2E,4Z,6Z,8Z)-2,4,6,8-decatetraene indicating the stereochemistry of the product 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,8Z)-2,4,6,8-decatetraene.

To state:

The stereochemistry of the product.

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