A variation of the acetamidomalonate synthesis can be used to synthesize serine. The process involves the following steps: Ethoxide ion deprotonates diethyl acetamidomalonate, forming enolate anion 1; Enolate anion 1 makes a nucleophilic attack on formaldehyde, forming tetrahedral intermediate 2; Protonation of the oxyanion forms alcohol 3; Acid hydrolysis yields dicarboxyamino alcohol 4; Decarboxylation leads to the final amino acid. Write out the mechanism on a separate sheet of paper, and then draw the structure of dicarboxyamino alcohol 4.

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.