Lamenallenic acid is a linear octadecatrienic fatty acid with the structural formula CH<sub>3</sub>CH=CH(CH<sub>2</sub>)<sub>8</sub>CH=C=CH(CH<sub>2</sub>)<sub>3</sub>COOH. The delta notation is 18:3-delta-5,6allene,16t. This is one of the rare allenic fatty acids found in nature, probably biosynthesized from laballenic acid.
Some authors have attributed the cis-configuration to the double bond in the position 16=17.
The allene group is responsible for the marked optical activity of the acid. Lamenallenic acid is levorotatory with (R)-configuration.
The acid was initially isolated in 1967 by Mikolajczak, Rogers, Smith, and Wolff in the seed oil of Lamium purpureum (10-16%), a plant of the Lamiaceae family. The compound is also found in the seed oil of other Lamiaceae: Lamium maculatum (~8%), Lamium album (~5%), Lamium amplexicaule (~5%).
The acid can be obtained by a highly enantioselective synthesis, utilizing the recently developed EATA (enantioselective allenylation of terminal alkynes) reaction and aerobic oxidation reaction.