Abstract
Epoxidation of the C=C double bond in unsaturated norlignans derived from hydroxymatairesinol was studied. The intermediate epoxides were formed in up to quantitative conversions and were readily further transformed into tetrahydrofuran, aryltetralin, and butyrolactone products—in diastereomeric mixtures—through ring-closing reactions and intramolecular couplings. For epoxidation, the classical Prilezhaev reaction, using stoichiometric amounts of meta-chloroperbenzoic acid (mCPBA), was used. As an alternative method, a catalytic system using dimeric molybdenum-complexes [MoO2L]2 with ONO- or ONS-tridentate Schiff base ligands and aqueous tert-butyl hydroperoxide (TBHP) as oxidant was used on the same substrates. Although the epoxidation was quantitative when using the Mo-catalysts, the higher temperatures led to more side-products and lower yields. Kinetic studies were also performed on the Mo-catalyzed reactions.
Highlights
In 1936, Haworth introduced lignans as a group of plant-based compounds consisting ofIn 1936, Haworth introduced lignans as a group of plant-based compounds consisting of β-β0 -linked dimeric phenylpropane units (Figure 1) [1]
Results and Discussion norlignans reacted at the double bond forming the epoxide-intermediate as two diastereomers
The formed epoxides were subject to rapid intramolecular nucleophilic attack to give nucleophilic were not stereospecific, possible stereoisomers were formed
Summary
In 1936, Haworth introduced lignans as a group of plant-based compounds consisting of. In 1936, Haworth introduced lignans as a group of plant-based compounds consisting of β-β0 -linked dimeric phenylpropane units (Figure 1) [1]. Similar to other natural phenolics such β-β-linked dimeric phenylpropane units (Figure 1) [1]. Similar to other natural phenolics such as as stilbenes and flavonoids, lignans are formed through the shikimic acid pathway [2]. Lignans have stilbenes and flavonoids, lignans are formed through the shikimic acid pathway [2]. Lignans are found in foods, for example, flaxseed, sesame, chickpeas anticancer properties [3,4,5,6]. Lignans are found in foods, for example, flaxseed, sesame, and cereals (rye, oat, barley), and red wine contains high levels of lignans. Lignans are found in foods, for example, flaxseed, sesame, and cereals (rye, oat, barley), and red wine contains high levels of lignans. [7]
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