NEW MATERIAL:A compound of formulaI.

EXAMPLE: Ethyl-3,7-dimethyl-6-hydroxy-2,4,7-octatrienoate.

USE: A synthetic intermediate for antitumor agents, etc. useful as a precursor for synthetic intermediates of retinoic esters or aromatic retinoids.

PROCESS: A compound of formula II is photooxidized in the presence of a photosensitizer with visible light to give a compound of formula III, which is then reduced to afford the compound of formulaI, Tetraphenylporphine or Rose Bengal may be cited as the photosensitizer. Pure oxygn or air may be used as the oxygen source for the photooxidation. The reduction may be carried out by either one of a reducing agent or catalytic hydrogenation.