Specific enolate equivalent, for carboxylic

Specific enol equivalents for carboxylic acid derivatives... 

Among the enolates of carboxylic acid derivatives, esters are the most widely used. Ester enolates cannot be used in crossed aldols with aldehydes because the aldehyde is both more enolizable and more electrophilic than the ester. It will just condense with itself and ignore the ester. The same is true for ketones. A specific enol equivalent for the ester will therefore be needed for a successful ester aldol reaction. 

For the remainder of this section we shall look at how to make specific enol equivalents of the remaining carboxylic acid derivatives. 

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