Beginning with diethyl malonate and any other reagents of your choice, show an efficient synthesis of methyl 2

Question

Beginning with diethyl malonate and any other reagents of your choice, show an efficient synthesis of methyl 2-ethylbutanoate.

Answer 1

Step 1.
Start with diethyl malonate. Treat this with a base such as LDA (lithium diisopropylamide) followed by ethyl iodide. This will give diethyl 2-ethylmalonate.

Step 2.
Using the product from the last reaction, diethyl 2-ethylmalonate, repeat the above sequence ie treat the diethyl 2-ethylmalonate with LDA followed by ethyl iodide. The product od this reaction will be diethyl 2,2-diethylmalonate

Step 3.
Take the product from the last reaction, diethyl 2,2-diethylmalonate, and treat it with an aqueous KOH solution to hydrolyse the esters. The product of that reaction will be 2,2-diethylmalonic acid.

Step 4.
Heat a solution of the above product, 2,2-diethylmalonic acid, to decarboxylate ie lose one of the acid groups. The product of this reaction will be 2-ethylbutanoic acid.

Step 5.
React the above product, 2-ethylbutanoic acid, with SOCl2 to form the acid chloride, 2-ethylbutanoyl chloride.

Step 6.
Finally react the above product, 2-ethylbutanoyl chloride, with methanol to give your desired product methyl 2-ethylbutanoate.

This is a standard type synthesis for compounds of this type. Hope this helps.

Answer 2

Use butanol with a strong base.