PURPOSE: To obtain a new compound, having antitumor activity and useful as an antitumor agent.

CONSTITUTION: A compound of formula I [A is formula II or III (R1 and R2 are H or alkyl); X is OH, halogen, etc.], e.g. 2-(2,6-dimethyl-8-(tetrahydropyran-2- yloxy)-2,6-octadienyl-4-methoxyphenol. This compound is obtained by etherifying geraniol according to a method for reacting, e.g. the geraniol with 2,3-dihydro-4 H-pyran, protecting the OH of the geraniol with tetrahydropyran-2-yl (THP), then reacting the protected geraniol with sulfuryl chloride in the presence of a hydrogen chloride capturing agent such as pyridine in a solvent such as THF, chlorinating the ene, subsequently reacting the resultant compound of formula IV with an alkali metallic salt of p-methoxyphenol in the presence of a phase- transfer catalyst such as a crown ether in a solvent such as benzene and subjecting the resultant compound of formula V to the Claisen rearrangement.