Laballenic acid
Laballenic acid is a linear fatty acid composed of 18 carbon atoms, with two consecutive double bonds in position 5=6=7. It has the structural formula CH3-10-CH=C=CH-3-COOH.
The acid is one of the rare allenic fatty acids found in nature.
Discovery
The acid was initially isolated in 1964 from the seed oil of Leonotis nepetifolia, a plant of the family Lamiaceae by M.O. Bagby, C.R. Smith Jr., and I.A. Wolff, and identified by the same authors a year later.Laballenic acid has also been found in Phlomoides tuberosa.
Synthesis
Several methods of synthesis have been published. An efficient and enantioselective synthesis dates back to the year 2022. A further enantioselective synthesis is based on copper(II) bromide catalysis and the use of diphenylprolinol as a chiral auxiliary.It has also been reported that lamenallenic acid is probably biosynthesized from laballenic acid.
Physical properties
Laballenic acid has axial chirality and is therefore optically active. The absolute configuration of laballenic acid was determined by stereoselective synthesis.There exist two configurations: the -form and the -form of laballenic acid. The naturally occurring acid has the R-configuration: it is an isomer of linoleic acid related with the similar phlomic acid.