Answer:
See detailed mechanism in the image attached
Explanation:
The mechanism shown in detail below is the synthesis of serine in steps.
The first step is the attack of the ethoxide ion base on the diethyl acetamidomalonate substrate giving the enolate and formaldehyde.
The second step is the protonation of the oxyanion from (1) above to form an alcohol as shown.
Acid hydrolysis of the alcohol formed in (3) above yields a tetrahedral intermediate, a dicarboxyamino alcohol.
Decarboxylation of this dicarboxyamino alcohol yields serine, the final product as shown in the image attached.
