Synthesis of the Anti-Melanogenic Glycerol Fatty Acid Ester Isolated from the Tuber-Barks of Colocasia antiquorum var. esculenta

(2′ S )-1- O -9-Oxo-(10 E ,12 E )-octadecadienoyl glycerol, a natural anti-melanogenic monoglyceride, is synthesized for the first time. The chiral pool based route employed not only confirms the absolute configuration, but also illustrates the first synthetic entry to the ( E , E )-diene keto acid, which is another molecule of biological importance. The confusion caused by the misinterpreted 1 H NMR spectroscopic data for the ( E , E )-diene motif in the literature is discussed. The first unequivocal piece of evidence for the assigned (12 E ) configuration is also presented.