4-Hydroxystilbenes

The stilbenes (165) and (166) were prepared as shown. Poly-hydroxystilbenes, e.g. (167), were obtained using dihydroxybenzal-... 

Lewis, F. D. Crompton, E. M. Hydroxystilbene isomer-specific photoisomerization versus proton transfer. J. Am. Chem. Soc. 2003, 125, 4044-4045. 

Hydroxymethyl-4,8-dimethylfuro[2,3-/z]chromen-2-one was realized in an efficient manner via a Claisen rearrangement of 4-(hydroxybut-2-ynyloxy)-4-methylchromen-2-one as depicted in the following scheme. Other examples with substitution of hydroxyl and with other substituents, such as chloro, amino, acetoxy were also reported <06JHC763>. A new approach for the synthesis of oxygenated benzo[fe]furans was developed via epoxidation and cyclization of 2 -hydroxystilbene <06T4214>. 

CONCENTRATION OF HYDROXYSTILBENE COMPOUNDS AND QUERCETIN (MG/ML) IN DIFFERENT WINES FROM PORTUGUESE MAINLAND AND AZORES ISLANDS... 

Cho DI, Koo NY, Chung WJ, Kim TS, Ryu SY, Im SY, Kim KM. 2002. Effects of resveratrol-related hydroxystilbenes on the nitric oxide production in macrophage cells Structural requirements and mechanism of action. Life Sci 71 2071-2082. 

Calderon AA, Tapata JM, Pedreno MA, Munoz R, Ros Barcelo A. 1992. Levels of 4-hydroxystilbene-oxidizing isoperoxidases related to constitutive disease resistance in in-vitro-cultured grapevine. Plant Cell Tissue Organ Cult 29 63-70. 

Pezet R, Pont V. 1990b. Relation between the chemical structure and the biological activity of hydroxystilbenes against Botrytis cinerea. J Phytopathol 130 1-8. 

Eq. 3.48 shows a specific radical reaction. Thus, the formed sp2 carbon-centered radical cyclizes at the vinylic position via 5-exo-trig manner and subsequent (3-cleavage to produce an o-hydroxystilbene skeleton (137), together with evolution of S02 [147, 148]. This reaction has the appearance of a 1,4-transfer of the phenylvinyl group from the sulfur atom to an sp2 carbon atom. 

A 24-analog hydroxystilbene library 34 was constructed from the Horner-Emmons olefination of four resin-bound hydroxybenzaldehyde BBs 33 and six different benzyl phosphonate anions [32], Screening for activity in a cell-based estrogenic assay identified several analogs such as 35 with IC50 values in the 5-15 pM range. 

Langer and co-workers [24,25] converted alcohols and phenols prior to GC analysis into TMS ethers by the action of HMDS. The method using silylation with HMDS—TMCS (2 1) was used for the GC of ethylene and diethylene glycols on Apiezon L [26], glycerol on SE-30 [27], polyethers of glycols on XE-61 [28], hydroxystilbenes on SE-52 [29], some flavonoides and related substances on SE-30 [30], plant phenols and related substances on OV-1, OV-17 and OV-25 [31], anthocyanines on OV-225 [32] and amino-chromes on SE-30 [33], Different terpene alcohols were silylated by Seidenstucker [34] within 10 min by heating at 40-60°C with a 6—8-fold excess of TMS-acetamide. The separation was performed on a stainless-steel column (50 m X0.25 mm I.D.) coated with Apiezon L. 

Hydroxystilbenes such as resveratrol (Figure 29) have been identified in several unrelated families, including the grapevine Vitis vinifera (Vitaceae), peanut Arachis hypogaea (Leguminosae), Veratrum grandifolia... 

The details of the reaction conditions used in this study have been described elsewhere (Dershem, S. M., et al., Holzforschung Fisher, T. H., et al., J. Org. CAem., in press). To test the importance of a p-hydroxyl substituent, the kinetics of oxidation of three benzyl alcohols p-hydroxybenzyl alcohol, (1), m-hydroxybenzyl alcohol, (2), and 4-hydroxy-3-methoxybenzyl alcohol, (3), were examined under alkaline nitrobenzene oxidation conditions. Some l-(4-hydroxyphenyl)-2-(4 -substituted phenyl)ethanols, (4), were synthesized as / -l lignin model compounds and subjected to alkaline nitrobenzene oxidation at 120 °C to study substituent effects. For controls, some of these compounds were reacted with or without nitrobenzene, alkaline catalyst, or water. In an effort to determine the effects of substituents on the oxidative-cleavage reaction of 4-hydroxystilbenes (5), a series of competitive rate experiments using both nitrobenzene and copper(II) as the oxidants in 2N NaOH was performed (Dershem, S. M., et al., Holzforschung, in press). 

Oxidation of Hydroxystilbene Derivatives with Nitrobenzene and Cop-per(II). To serve as / -l lignin model compounds, some 1-(4-hydroxyphenyl)-2-(4,-substituted phenyl)ethanols, (4), (Figure 2) were synthesized ( ). The / -l lignin model was chosen, since it is the only common lignin unit structurally suitable for substituent-reactivity studies on oxidation rates. In an effort to study... 

Table II. Relative Rates of Nitrobenzene and Copper(II) Oxidations of 4-Hydroxystilbenes 5 in 2N NaOH at 155 °C1...

Stojanovic S, Brede O. (2002) Elementary reactions of the antioxidant action of trans-stilbene derivatives Resveratrol, pinosylvin and 4-hydroxystilbene. Phys Chem Chem Phys A 757-764. 

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