Synthesis and absolute configuration of hylodiglyceride isolated from Hylodendron gabunensis

Abstract

A recently isolated bismonoglyceride of heptadecanedioic acid, which represents a novel type of natural monoglycerides (i.e., with two instead of only one glycerol unit in the molecular architecture), was synthesized in enantiopure forms using a chiral-pool based approach with the 17-carbon chain constructed from undec-10-enoic acid and oct-7-en-1-ol via a cross metathesis and the stereogenic centers derived from (R)-(2,2-dimethyl-1,3-dioxolan-4-yl)methanol. An analogue with a longer alkyl chain was also synthesized. The synthetic samples not only allowed for establishment of the absolute configuration but also helped to reveal some minor yet unignorable errors in the 1H NMR data for the natural product. Optical rotation and NMR data acquired in DMSO and DMSO-d6, respectively, are also presented.