91Ó°ÊÓ

It is defined as the reaction that occurs between two different esters in which one ester contains alpha hydrogen and another may or may not contain alpha hydrogen and the ester which contains alpha hydrogen is added slowly to the ether which does not have alpha hydrogen and a reaction followed by enolate formation by LDA.

As per the reaction given the compound added slowly having alpha hydrogen therefore, abstraction of acidic proton takes place by LDA hence, enolate formed followed by an attack of the compound having no alpha hydrogen to the enolate followed by HCl condensation occur and beta keto ester formed:

In the given reaction the compound added slowly is having alpha hydrogen therefore, abstraction of acidic proton takes place by LDA hence, enolate is formed followed by an attack of the compound having no alpha hydrogen to the enolate ion with the removal of -OH₃followed by HCl condensation occurs and beta keto ester formed: