Abstract The reaction of a hydroxylated base with 3-chloro-2-methyl-6-methylene 1, 7- octadiene in the presence of a palladium complex and a quaternary ammonium salt gives a novel tetraene: 2-methyl-6-methylene-1, 3E, 7-octatriene, which is a new C 10 terpene synthon. A novel access to pseudo-ionone is also described.