Clickable Lipids: Azido and Alkynyl Fatty Acids and Triacylglycerols

Abstract

Hydroxy fatty acids (FAs), which were isolated from glycolipids that can be prepared fermentatively from fats and oils, have been synthetically modified to contain azide and alkyne functional groups. These particular functional groups were chosen because they can participate in a copper-catalyzed reaction that combines them to form a 1,4-triazole, known as a ''click'' reaction, which has been widely used in a variety of fields but remains underutilized in FA chemistry. Depending on the starting hydroxy FA, these groups can be close to the carboxy unit (using 3-hydroxydecanoate) and hence the polar glycerol group, or distant from it (using 17-hydroxyoctadecanoate). These structural alternatives will impart different properties to the triacylglycerols that are subsequently prepared from the modified FA. Finally, the click reaction was used to conjugate triacylglycerols to each other and to other molecules such as a glycolipid or a protected amine.

Soybean oil based thermoset networks via photoinduced CuAAC click chemistry

“…In order to take these benefits into account, the CuAAC reaction of multifunctional alkyne (Al‐SBO) and azide (Az‐SBO) compounds was activated by UV light in the presence of the CuBr 2 /PMDETA/DMPA catalyst system at room temperature. First, multifunctional azide and alkyne containing SBOs were prepared by ring‐opening reactions using sodium azide and propargyl alcohol, which were previously described in the literature . Their structures were initially confirmed by FTIR analysis, in which typical bands of azide and alkyne appeared at 2120, 2100 and 3350 cm −1 , respectively.…”

Epoxidizable Fatty Amide–Phenol Conjugates

“…Removal of solvent and chromatography afforded styrene derivative 5c (108 mg, 70%). 1 Molecule 1b (0.37 g, 1.9 mmol), PPh 3 (0.55 g, 2.1 mmol), and 17-hydroxy oleic acid methyl ester [17] (0.72 g, 2.3 mmol), were dissolved in 10 mL THF. To this mixture was added diisopropyl azodicarboxylate (DIAD, 0.42 g, 2.1 mmol) in 2 mL THF.…”

“…After 2 h, the solvent was removed, and column chromatography gave molecule 7 (204 mg, 81%). Molecule 6b (350 mg, 0.6 mmol) was deprotected and coupled similarly with 2 equiv of 17-azido oleic acid (prepared as reported by us previously [17]). The DMF solvent was removed, and the crude taken up in THF with approximately 100 lL H 2 O, then PPh 3 (393 mg, 1.5 mmol) was added.…”

“…This route requires an alcohol reacting partner, for which we chose a hydroxylated fatty acid, namely 17-hydroxy oleic acid. The preparation of this hydroxy fatty acid from fermentation of fats or oils was described by us previously [17]. Isolation of the arylated hydroxy fatty acid was straightforward ( Fig.…”

“…This is a case where HCl deprotection of chloroacetyl could well be unacceptable (hydrolyzing the methyl ester or perhaps adding across the C=C). The deprotected amine groups were then coupled to 17-azido oleic acid, a compound we recently reported [17]. The resulting di-azide 8a could be used in click reactions, although, if the products were intended for later epoxidation and crosslinking, problems might arise with the 1,2,4-triazole that the click reaction produces: it could be oxygenated by an epoxidation agent.…”