Abstract:Ligstroside, ligstroside aglycone, and oleocanthal are extra virgin
olive oil (EVOO) bioactive phenols poorly represented in olive leaves.
Semisynthetic pathways to achieve them, starting with largely available
natural precursors, are proposed as alternative solution with respect
to their low effective extraction or total synthesis. In the present
work, we propose the first green chemocatalytic method to obtain,
in the same semisynthetic cascade, ligstroside, ligstroside aglycone,
and oleocanthal starting from… Show more
“…8 a). Compared to the previously reported method using microwave-assisted Krapcho dealkoxycarbonylation, this catalytic reaction can produce oleocanthal in relatively better yield from ligstroside 27 . Figure 8 Catalyst applications.…”
Section: Resultsmentioning
confidence: 90%
“…Smith et al reported the total synthesis of oleacein from d -lyxose over 10 steps, with a total yield of 13% 25 . Compared to total synthesis, semi-synthesis is a more efficient, more economical, and greener alternative 26 , 27 . Vougogiannopoulou et al reported the direct conversion of oleuropein into oleacein via Krapcho decarboxylation using two equivalents of sodium chloride; however, the oleacein yield was only 20% 28 .…”
In this study, we developed a new synthetic strategy to convert secoiridoid glucosides into unique dialdehydic compounds using solid acid catalysts. Specifically, we succeeded in the direct synthesis of oleacein, a rare component of extra-virgin olive oil, from oleuropein, which is abundant in olive leaves. Whereas the conventional total synthesis of oleacein from lyxose requires more than 10 steps, these solid acid catalysts enabled the one-step synthesis of oleacein from oleuropein. A key step in this synthesis was the selective hydrolysis of methyl ester. Density functional theory calculations at the B3LYP/631+G (d) level of theory revealed the formation of a tetrahedral intermediate bonded to one H2O molecule. These solid acid catalysts were easily recovered and reused at least five times by simple cleaning. Importantly, this synthetic procedure was not only applicable to other secoiridoid glucosides, but could also be employed for the corresponding scale-up reaction using oleuropein extracted from olive leaves as the starting material.
“…8 a). Compared to the previously reported method using microwave-assisted Krapcho dealkoxycarbonylation, this catalytic reaction can produce oleocanthal in relatively better yield from ligstroside 27 . Figure 8 Catalyst applications.…”
Section: Resultsmentioning
confidence: 90%
“…Smith et al reported the total synthesis of oleacein from d -lyxose over 10 steps, with a total yield of 13% 25 . Compared to total synthesis, semi-synthesis is a more efficient, more economical, and greener alternative 26 , 27 . Vougogiannopoulou et al reported the direct conversion of oleuropein into oleacein via Krapcho decarboxylation using two equivalents of sodium chloride; however, the oleacein yield was only 20% 28 .…”
In this study, we developed a new synthetic strategy to convert secoiridoid glucosides into unique dialdehydic compounds using solid acid catalysts. Specifically, we succeeded in the direct synthesis of oleacein, a rare component of extra-virgin olive oil, from oleuropein, which is abundant in olive leaves. Whereas the conventional total synthesis of oleacein from lyxose requires more than 10 steps, these solid acid catalysts enabled the one-step synthesis of oleacein from oleuropein. A key step in this synthesis was the selective hydrolysis of methyl ester. Density functional theory calculations at the B3LYP/631+G (d) level of theory revealed the formation of a tetrahedral intermediate bonded to one H2O molecule. These solid acid catalysts were easily recovered and reused at least five times by simple cleaning. Importantly, this synthetic procedure was not only applicable to other secoiridoid glucosides, but could also be employed for the corresponding scale-up reaction using oleuropein extracted from olive leaves as the starting material.
“…In 2021, Mancuso and co-workers 42 proposed a green catalytic method to obtain ligstroside 3, ligstroside aglycone 5 and oleocanthal 7 starting from oleuropein 4, in the same semisynthetic cascade. Based on Samara's strategy, 39 the authors started from oleuropein 4.…”
Section: Ligstrosidementioning
confidence: 99%
“…More recently, the synthesis of oleocanthal 7 was described by Mancuso et al 42 starting from oleuropein 4 (Scheme 8), in four steps with 13% overall yield. The desired compound was obtained by the MW-assisted Krapcho dealkoxycarbonylation, from ligstroside 3.…”
Section: Oleocanthalmentioning
confidence: 99%
“…Scheme 8. Synthesis of Ligstroside Aglycone 5 and Oleocanthal 7 Reported by Mancuso and Co-Workers42 …”
Virgin olive oil (VOO) is the main fat consumed by populations in the Mediterranean basin, and phenolic compounds, minor components of this fat, are known to be responsible for diverse health benefits when consumed in a regular diet. According to numerous investigations, these benefits are mostly related to phenols such as tyrosol and hydroxytyrosol and secoiridoid derivatives such as ligstroside, oleuropein, oleocanthal and oleacein. These compounds are present in low concentrations, and for some of them, standards are not commercially available, hampering studies on the mechanisms underlying their biological activity. In order to contribute to a better knowledge of the bioactivity of these compounds and their metabolites, they must be available with high purity and in sufficient amounts for the assays. Chemical synthesis has been considered a convenient way to obtain these compounds. This Review will focus on the synthesis of representative VOO compounds, namely, ligstroside, oleuropein, oleocanthal, oleacein and analogues.
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