Abstract: Aliphatic acids containing an isoprenoid 1,5-diene moiety are prepared in high yields by the selective gamma alkylation of .alpha.,.beta.-unsaturated acids with allylic electrophiles. The gamma-regioselectivity of the alkylation is controlled by the use of the dicopper(I) dienolates prepared from the .alpha.,.beta.-unsaturated acids. The method offers a particularly facile means for synthesizing isoprenoid 1,5-diene natural products such as farnesoic acid by alkylation of senecioic acid with geranyl bromide; geranoic acid by alkylation of senecioic acid with 3,3-dimethallyl bromide; and dl-lanceol by alkylation of tiglic acid with an allylic bromide derived from dl-limonene. Such products find use in the synthesis of insect pheremones, insect juvenile hormones, and components of perfumes.