(a) Interpretation: The structures including stereochemistry of the methyl esters of endiandric acids D and E is to be drawn. Concept introduction: Curved arrows aid in determining the movement and flow of electrons in the reaction. The electrons that take part in the chemical reactions are shown by the curved arrows.

Question

The endiandric acids comprise a group of unsaturated carboxylic acids isolated from a tree that grows in the rain forests of eastern Australia. The methyl esters of endiandric acids D and E have been prepared from polyene Y by a series of two successive electrocyclic reactions: thermal ring closure of the conjugated tetraene followed by ring closure of the resultingconjugated triene. (a) Draw the structures (including stereochemistry) of the methyl esters of endiandric acids D and E. (b) The methyl ester of endiandric acid E undergoes an intramolecular [4 + 2] cycloaddition to form the methyl ester of endiandric acid A. Propose a possible structure for endiandric acid A.

Answer 1

Question

Chapter 27, Problem 27.58P

Interpretation Introduction

(a)

Interpretation: The structures including stereochemistry of the methyl esters of endiandric acids D and E is to be drawn.

Concept introduction: Curved arrows aid in determining the movement and flow of electrons in the reaction. The electrons that take part in the chemical reactions are shown by the curved arrows.

Interpretation Introduction

(b)

Interpretation: The methyl ester of endiandric acid E undergoes an intramolecular [4+2] cycloaddition to form the methyl ester of endiandric acid A. The structure for endiandric acid A is to be proposed.

Concept introduction: Curved arrows aid in determining the movement and flow of electrons in the reaction. The electrons that take part in the chemical reactions are shown by the curved arrows.

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