Stilbene, 4-hydroxy

Preparation of 2-Hydroxy-4,4 -Diamidinostilbene Dihydrochloride 10 grams of 2-hydroxy-4,4 -dicyanostilbene were suspended in 250 cc of absolute ethyl alcohol and the mixture saturated with dry hydrogen chloride at 0°C. The whole was left for eight days at room temperature. The imino-ether hydrochloride formed was filtered off, washed with dry ether and dried in the air for a short time. It was then added to 250 cc of 10% ethyl alcoholic ammonia and the whole heated for 5 hours at 45°C. The 2-hydroxy-4,4 -diamidino-stilbene dihydrochloride which separated was crystallized from 10% hydrochloric acid. It forms pale yellow needles, MP 357°C (decomposition). 

As discussed in Section 10.3, the system consisting of a diazonium ion and cuprous ions can be used for hydroxy-de-diazoniation at room temperature in the presence of large concentrations of hydrated cupric ions (Cohen et al., 1977 see Schemes 10-7 to 10-9). With (Z)-stilbene-2-diazonium tetrafluoroborate under these conditions, however, the major product of ring closure of the initially formed radical was phenanthrene (64%). When the cupric nitrate was supplemented by silver nitrate the yield increased to 86% phenanthrene. Apparently, the radical undergoes such rapid ring closure that no electron transfer to the cupric ion takes place. 

A short and efficient synthetic approach to hydroxy-substituted ( )-stil-benoids, as exemplified by the natural compound resveratrol (371b) via solid-phase CM, was reported by a Korean group (Scheme 71) [154]. When two different stilbenes were allowed to couple by catalyst C, all three kinds of possible stilbenes were obtained as an inseparable mixture. Anchoring 4-vinylphenol to Merrifield resin, followed by exposing the supported styrenyl ether 368 and diacetoxy styrene 369 (10 equiv) to the catalyst, inhibited self-metathesis of the supported substrate. Sequential separation of the homodimer formed from 369 by washing and subsequent cleavage of the resin 370 with acid provided (E)-stilbene 371a with complete stereocontrol in 61% yield. 

Wahrend (2-Hydroxy-2-phenyl-athyl)-phenyl-sulfon in Gegenwart von Protonen-Do-natoren zu Stilben gespalten wird (s.S. 633), erhalt man bei Abwesenheit der Donatoren unter C—C-Spaltung 7,2-Diphenyl-glykol und Athyl-phenyl-sulfon (s.S. 633). 

A series of N-substituted narceine amides (Section III,D,1) was prepared from 101 under the action of primary amines (100). Acid-catalyzed dehydration transformed these amides to corresponding imides (ene lactams) of the ( )-narceine imide (117) type (100). Similar transformations were performed in the hydrastine series (101). JV-Methylhydrastine (98) when treated with dilute ammonium hydroxide gave hydroxy lactam 127, which was dehydrated to (Z)-fumaridine (113) (5). Sodium borohydride was able to reduce the stilbene double bond in 98 to produce saturated lactone 132 (5). 

Sodium phenoxide, 32, 75 33, 43, 45 Sodium sulfhydrate, 31, 7 Sodium sulfide nonahydrate, 31, 6 Sommelet reaction, 33, 93 Sorbic acid, S-hydroxy-0-methyl, 3-lactone, 32, 57 Stannic chloride, 33, 91 Stearone, 33, 84 ms-Stilbene, 33, 88 Irans-Stilbene, 33, 89... 

Interestingly, Jacobsen et al. have also reported that addition of a /3-hydroxy ammonium salt to the reaction medium accelerates the isomerization in the presence of an /V-benzylated quinine salt epoxidation of cw-stilbene with (27) gives Zrarax-stilbene oxide with 90% ee as the major product (trans cis= >96 4).109 In 2000, Adam et al. reported that the isomerization ratio was related to the triplet-quintet energy gap of the radical intermediate which was affected by the... 

ZUURBIER, K.W.M., LESER, J., BERGER, T., HOFTE, A.J.P., SCHRODER, G., VERPOORTE, R., SCHRODER, J., Hydroxy-2-pyrone formation by chalcone and stilbene synthase with nonphysiological substrates, Phytochemistry, 1998,49, 1945-1951. 

From this point of view, a brief comparison of acyloxylation of cis- or irany-stilbenes in electrochemical and chemical conditions is also relevant. Oxidation of cis- or irany-stilbene at the platinum anode in the presence of acetic or benzoic acid gives predominantly meyo-diacylates of hydroxy-benzoin or, if some water is present, t/treo-monoacylate. None of the stereoisomeric erythro-mono-acylate and rac-diacylate were obtained in either case. There was no evidence of isomerization of cis- to trany-stilbene nnder the electrolytic conditions employed (Mango and Bonner 1964, Koyama et al. 1969). The sequence of reaction steps in Scheme 2.27 was proposed. Adsorption-controlled one-electron oxidation of the snbstrate takes place. Then the cis-stilbene cation-radical interact with acetate to form an oxonium ion. The phenyl groups in the oxoninm adopt the trans mntnal disposition which is thermodynamically preferential. The trany-benzoxoninm ion is the common intermediate for conversions of both cis- and trany-stilbenes and, of conrse, for all the final prodncts (Scheme... 

Treatment of either cis- or rrans-stilbene-2-carboxylic acids with chlorine or bromine leads to 4-halogeno-3,4-dihydro-3-phenylisocoumarins (58T<4)393). The reactions are stereospecific and are thought to involve intramolecular attack by the carboxyl group on a halonium ion. Ring closure to the corresponding 4-hydroxy compound also occurs stereo-specifically using peroxyphthalic acid (59JOC934). 

The powder THG results are also shown in Table 2. An unesterified azo compound (A-l) shows a small THG at all wavelengths measured in this experiments. On the other hand, ester derivatives such as acetate (A-2), nitrobenzoate (A-3) and acrylate (A-4) show a very large THG. The THG intensity is more than 10 times larger than that of the unesterified compound at 2.05 pm wavelength. The enhancement of THG in powders by esterification is observed not only in azo benzene derivatives but also in stilbene and benzylidene aniline derivative(28k These results have not been expected due to effects on an electronic state because esterification occurs at a hydroxy group... 

Six membered heterocyclics can be synthesized in various ways. Nitrogen analogues of stilbene, like the anilides of benzaldehyde or acetophenone sometimes form azaphenanthrenes 19). Similarly the plasma reaction of azobenzene yields a small amount of diazaphenanthrene 19>. Better results are observed in the cyclization of hydroxy, amino or nitro compounds. Suitable starting materials are molecules with two phenyl groups linked by a carbon or hetero atom. 

Amino-l,2,4-benzotriazine 1,2-dioxide Thin layer chromatography Thymidine-5 -phosphate iV,iV,iV, iV -Telramclhylphcnylcncdiamine Tetranitromethane 3,5,4 -Trihydroxy-frans-stilbene 2-Amino-2-hydroxy-l, 3-propanediol Time-resolved light-scattering p-[meso-5-5,10,15,20-Tetra(pyridyl)porphyrin]tetra kis[ (ns-(bipyridine) chloride ruthenium(II)]... 

The strategy is impressively simple the phthalazine derivative 15 can readily be prepared from quinine in one step. Being a divinyl derivative, it can be submitted as a cross-linking unit in the radical polymerization of methyl methacrylate (MMA) or 2-hydroxy methacrylate (HEMA). Thereby, an immobilized (DHQ-PHAL) derivative 16 is obtained, which is suited for the asymmetric dihydroxylation of frantr-stilbene (>99 % ee) and ( )-cinnamic acid methyl ester (>99 % ee. Table 1). The insoluble catalyst can be recovered by simple filtration, and its repeated... 

Reduction of a, -epoxy ketones. a,P-Epoxy ketones are reduced by NaTeH rc-gioselectively to (3-hydroxy ketones. Unactivated epoxides, such as stilbene oxide and a,3-epoxy alcohols, are not reduced. 

The structural novelty and various biological activities elicited by this compound prompted the synthesis of 138 by different workers following different strategies. Some of the successful reports are described here. Banwell et al. reported the synthesis of ( )-aiphanol (154) based on the standard procedures of Stermitz s modification (124). A mixture of ( )-138, its regioisomer (157), and their stereoisomers 158 and 159 was obtained by treatment of the stilbene, piceatannol (144), and 4-hydroxy-3,5-dimethoxyciimamyl alcohol (156) with silver carbonate in ace-tone-benzene (755). The reaction steps for the synthesis of starting materials 144 and 156, and their oxidative coupling steps are shown in Schemes 9a, 9b, and 9c. 

Photogeneration efficiencies of 4,4 -(9-oxo-9H-fluorene-2,7-diyl)bis(azo)-bis[N-(2-chlorophenyl)-3-hydroxy-2-naphthalenecaiboxamide] (AZO-FO) in single- and dual-layer configurations were measured by Umeda et al. (1990). The dual-layer materials contained 4-N,N-bis(4-methylphenyl)amino-a-phenyl-stilbene (MAPS) in the transport layer. Figure 5 shows the field dependencies. 

The movement of the catalytic domain of the Rieske protein is related to the binding of Qo site inhibitors. Stigmatellin or 5-undecyl-6-hydroxy-4,7-dioxobenzothiazol (UHDBT) bind directly to tiie exposed HislSl of the Rieske protein [6] and fix the Rieske protein in the h position , while binding of MOA-stilbene or myxothiazol favors tiie ci position [23]. 

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