A pair of compounds which is the most reasonable source of all the carbon atoms in the preparation of the given epoxide is to be determined. Concept Introduction: Dianion can be prepared from alpha halogenated carboxylic acids by double deprotonation using strong bases such as LDA. Reaction of dianion of these alpha halogenated carboxylic acids with ketones yield epoxy acids or glycidic acids. In the first step, a new carbon-carbon single bond is formed between the carbonyl carbon of the ketone and the alpha carbon atom of the dianion. In the second step, the oxygen atom in ketone attacks on the alpha carbon atom of the dianion to form a new carbon-oxygen single bond. The oxygen atom in the ketone group is a source of oxygen in the epoxides . The original carboxylic acid must have a good leaving group attached to the alpha carbon atom. In the process, a carbon-carbon single bond and a carbon-oxygen single bond are formed.

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Chapter 21, Problem 62DSP

Interpretation Introduction

Interpretation:

A pair of compounds which is the most reasonable source of all the carbon atoms in the preparation of the given epoxide is to be determined.

Concept Introduction:

Dianion can be prepared from alpha halogenated carboxylic acids by double deprotonation using strong bases such as LDA.

Reaction of dianion of these alpha halogenated carboxylic acids with ketones yield epoxy acids or glycidic acids.

In the first step, a new carbon-carbon single bond is formed between the carbonyl carbon of the ketone and the alpha carbon atom of the dianion.

In the second step, the oxygen atom in ketone attacks on the alpha carbon atom of the dianion to form a new carbon-oxygen single bond.

The oxygen atom in the ketone group is a source of oxygen in the epoxides.

The original carboxylic acid must have a good leaving group attached to the alpha carbon atom.

In the process, a carbon-carbon single bond and a carbon-oxygen single bond are formed.

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