Laccase‐Catalyzed Dimerization of Hydroxystilbenes

Abstract

A series of hydroxystilbenes, analogues of the bioactive phytoalexin resveratrol, were synthesized and submitted to the catalytic action of a laccase from Trametes pubescens in a biphasic system made of ethyl acetate and acetate buffer. Oxidation took place at the 4'-hydroxy (4-hydroxy) position of the hydroxystilbenic moieties, followed by radicalradical coupling dimerization reactions. Most of the products were isolated in good yields and fully characterized. Depending on the substrates, three different dimeric products could be identified, the main products usually being 4-O-a-ß-5 (dihydrofuran-like) dimers.

A joint experimental and theoretical investigation on the oxidative coupling of resveratrol induced by copper and iron ions

“…1). Interestingly the same compound is formed by resveratrol in presence of laccase, an oxidoreductase enzyme containing four copper ions [38]. Indeed, we observed the same MS and MS/MS spectra obtained in the case of a resveratrol-copper(II)sulfate solution as with an ethyl acetate solution of resveratrol and laccase in buffer solution.…”

Biocatalyzed synthesis of enantiomerically enriched β-5-like dimer of 4-vinylphenol

“…As shown in Scheme 3, six dimers (4)(5)(6)(7)(8) could be isolated and characterized. The main product, albeit with lower isolated yield in comparison to other substituted phenolic precursors, was the "usual" ˇ-5-like dimer 4, whose structure was easily confirmed by mass spectrometry (m/z at 238 Da), 1 H NMR (signals due to para-substituted and trisubstituted aromatic rings, to a vinyl moiety and to an ABX system were clearly identified, see Section 2), and 13 C NMR analysis.…”

“…Specifically, different authors have studied the laccase-catalyzed oxidation of propenylphenols, like isoeugenol (1, Scheme 1) [6], coniferyl alcohol [6], trans-resveratrol [7] and other hydroxystilbenes [8].…”

Synthesis of Enantiomerically Enriched Dimers of Vinylphenols by Tandem Action of Laccases and Lipases

“…[9] For instance, a mixture of dimeric and tetrameric derivatives was isolated in approximately 30-40% yield from the oxidation reaction of 1 or 2 catalyzed by Rhus vernicifera laccase in an acetone-water mixture. [7] A more precise control of the oxidation process was observed with the stilbenic phytoalexin 3, allowing the isolation of the dehydrodimer 4 (corresponding to the structure b-5 of Figure 1) in 31% yield.…”