Biosynthesis of Resveratrol Dimers by Regioselective Oxidative Coupling Reaction

Abstract

A wide array of natural resveratrol dimers was prepared by the regioselective oxidative coupling reaction of 3,5-di-(tertbutyl)resveratrol using several types of metal oxidants (Ag 2 O, Ag 2 CO 3 , MnO 2 , and FeCl 3 ·6H 2 O) in different solvent systems (benzene-acetone and dichloromethane). Subsequent debutylation of these coupling products resulted in racemic pallidol and ampelosin F.

Chemistry and Biology of Resveratrol-Derived Natural Products

“…Expanding upon the work of the Hou group, Li and co-workers reported a series of oxidations of stilbene 146 using inorganic oxidants in several solvent systems. 178 In this communication, the Li group reports reaction conversions and percent recovered starting material, but in several cases, these values add up to more than 100%, making yield estimation difficult. They found that when 146 was oxidized by 1 equiv of either Ag 2 CO 3 or MnO 2 in CH 2 Cl 2 , they observed 59% and 54% reaction conversion to quinone methide 147 with 64% and 76% recovered starting material, respectively (Table 4 ).…”

Electrochemical Dimerization of Phenylpropenoids and the Surprising Antioxidant Activity of the Resultant Quinone Methide Dimers

“…Ar ange of 3,5-di-tert-butyl-4-hydroxystilbene substrates were prepared from commercially available starting materials in 2-3 steps (see Supporting Information). Va rious protecting groups were tolerated on the resorcinol ring without diminishing the yield (5)(6)(7). When the tert-butyl substituents at C3 were exchanged with trialkylsilyl groups (8,9), the yield diminished due to the decreased stability of the QMDs,which we have reported on previously.…”

“…[1][2][3] Their biosynthesis is hypothesized to proceed via the regio-and stereoselective coupling of phenoxyl radicals of form 2a-2c to generate products such as hierochin D( 3)v ia C3ÀC8' coupling and quadrangularin A( 4)v ia C8ÀC8' coupling ( Figure 1A). [5][6][7] Our previous approaches employed ferrocenium hexafluorophosphatea s am ild stoichiometric oxidant to promote dimerization of protected resveratrol derivatives,w hich ultimately enabled the total synthesis of several dimeric and tetrameric resveratrol natural products. [5][6][7] Our previous approaches employed ferrocenium hexafluorophosphatea s am ild stoichiometric oxidant to promote dimerization of protected resveratrol derivatives,w hich ultimately enabled the total synthesis of several dimeric and tetrameric resveratrol natural products.…”

Strategies and Methods for the Syntheses of Natural Oligomeric Stilbenoids and Analogues

“…However, these reactions yields remain usually relatively low as various dimeric structures might be produced simultaneously due to competing mechanisms notwithstanding the formation of insoluble high molecular weight polymers. An interesting and most recent approach (2010) is that adopted by Li et al [110] who, in continuation of Hou's work [55], subject 11,13-di-tert-butylresveratrol to one electron oxidants and obtained dimers in decent yields. It may well be that carefully designed monomeric units subjected to oxidative coupling (possibly cross-coupling) would produce commonly encountered native oligostilbenes.…”