trans-2-EN-valproic acid (CAS NO.: ), with its systematic name of 2-Propyl-2(E)-pentenoic acid, could be produced through many synthetic methods.

Following is one of the synthesis routes:

Dehydrobromination of the ethyl ester of 2-bromo-2-propylpentanoic acid (I) in the presence of a tertiary amine affords a mixture of the isomers of 2-propyl-2-pentenoic acid ethyl ester (IIa) and (IIb), from which the major component, the trans-isomer (IIa), is separated and saponified to obtain trans-2-propyl-2-pentenoic acid (trans-2-en-valproic acid) (H. Schafer, personal communication).