1.Explanation | Common mistakes | Hint for next step

When diethyl malonate is treated with sodium ethoxide, the ethoxide ion functions as a base and removes the acidic hydrogen atom from diethyl malonate to form the reactive carbanion.

2.Explanation | Common mistakes | Hint for next step

The carbanion formed from the removal of a proton from diethyl malonate acts as a nucleophile and attacks the electrophilic carbon of the epoxide ring at the less substituted side. This leads to opening of the epoxide ring, to form an alkoxide ion.

3.

Explanation | Common mistakes

The alkoxide formed by the opening of the epoxide ring acts as a nucleophile and attacks the electrophilic carbon of one of the ester group of the same molecule, along with loss of the ethoxide ion. It leads to the formation of a lactone having a molecular formula c9h14o4

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