Synthesis of valproic acid

Valproic acid (2-propylpentanoic acid) is an antiepileptic drug. Its structure, an acetic acid with two propyl groups on the α carbon, is exactly what the malonic synthesis provides: diethyl malonate is alkylated twice with propyl bromide, and the resulting diester is hydrolysed and decarboxylated on heating.

This is one of the industrial routes to it; another, very similar one starts from ethyl cyanoacetate.