Abstract Ethyl 2-acetyl-4,9-decadienoate obtained by palladium catalyzed reaction of butadiene and ethyl acetoacetate was converted to 4,9-decadienoate. Hydroboration of the terminal olefin gave 10-hydroxy-4-decenoate. After hydrogenation and protection of the hydroxyl group, the double bond was created at the conjugated position by introduction of phenylseleno group and subsequent oxidative removal to give 10-hydroxyl-2-decenoic acid.