Stilbenes derivatives

In addition to benzene and naphthalene derivatives, heteroaromatic compounds such as ferrocene[232, furan, thiophene, selenophene[233,234], and cyclobutadiene iron carbonyl complexpSS] react with alkenes to give vinyl heterocydes. The ease of the reaction of styrene with sub.stituted benzenes to give stilbene derivatives 260 increases in the order benzene < naphthalene < ferrocene < furan. The effect of substituents in this reaction is similar to that in the electrophilic aromatic substitution reactions[236]. 

Chlorides are inert. However, the reaction ofp-chlorobenzophenone (9) with a styrene derivative proceeds satisfactorily at 150 C by u.sing dippb [l,4-bis(-diisopropylphosphino)butane] as a ligand to give the stilbene derivative 10. However, dippp [l,3-bis(diisopropylphosphino)propane] is an ineffective ligand[13]. On the other hand, the coupling of chlorobenzene with styrene proceeds in the presence of Zn under base-free conditions to afford the cis-stilbene 11 as a main product with evolution of H . As the ligand, dippp is... 

Stilbene Derivatives. Most commercial brighteneis aie bistria2inyl derivatives (1) of 4,4 -diarmnostilbene-2,2 -disulfonic acid (Table 1). The usual compounds are symmetric preparation begias with reaction of 2 moles of cyanuric chloride derivatives with 1 mole of... 

Table 1. Symmetrical Stilbene Derivatives used as Fluorescent Whitening Agents...

A further group of whiteners was found in the acylamino (R,R ) derivatives (16) of 3,7-diaminodibenzothiophene-2,8-disulfonic acid-5,5-dioxide. The preferred acyl groups are aLkoxybenzoyls (72—74). These compounds give a greenish fluorescence and are relatively weak in comparison with stilbene derivatives on cotton however, they show good stabiUty to hypochlorite. 

Freedom of rotation about the double methylene bridge in the compound (7) (dimethyl 4,4 -(l,2-ethanediyl)bisben2oate [797-21-7]) destroys the rod shape of the molecule and prevents Hquid crystal formation. The stilbene derivative (8) (dimethyl 4,4 -(l,2-ethenediyl)bisben2oate [10374-80-8]) however, is essentially linear and more favorable for Hquid crystal formation. 

Methyl groups on C-linked phenyl attached to oxazoles, isoxazoles and oxadiazoles react with benzylidineaniline to give stilbene derivatives (Scheme 51) <78AHC(23)l7l). 

The condensation of 5-phenyl-3-(p-tolyl)isoxazole (210) with benzylidineaniline gave the stilbene derivative (211) (78AHC(23)l7l). 

Several compounds that inhibit vesicular glutamate transport have been identified These include the dyes Evans Blue and Rose Bengal. In addition, the stilbene derivative 4,4 -diisothiocyanatostilbene-2,2 -disulfonic acid (DEDS), a compound commonly used as a specific inhibitor of anion channels, inhibits vesicular glutamate transport. Most known inhibitors have limited use as they are membrane impermeant, with the exception of Rose Bengal. 

Ar CH=CHAr and ( >Ar C(Ar)=CH2, as main products (Ikenaga et al., 1986). This loss of regioselectivity disqualifies this reaction for synthetic purposes. Surprisingly, however, a-styrylstannanes (10.24, R=CH3, C2H5, n-C4H9) selectively gave the (Z)- rather than the (is)-stilbene derivatives (Scheme 10-63 Kikukawa et al., 1986). 

Most of the olefins shown so far, for which reversibility of the bromonium ion formation had been demonstrated, are particular olefins, in which either steric bulk impedes the product forming step, or ring strain in the dibromide product retards this step. In order to check the general occurrence of the reversibility during the bromination reaction, a further approach, based on the cis-trans isomerization of stilbene derivatives during the bromination of the cis isomers, was devised. 

The investigated cw-stilbene derivatives, 4-methoxy, 4,4 -dimethyl, unsubstituted, and 4,4 -bis(trifluoromethyl)stilbenes, had k2 values spanning 6-7 powers of ten both in methanol and in acetic acid. Products 2, 4, 5 and 6 were formed. Table 8 reports the results of the cis-trans isomerization test in acetic acid (ref. 29). No acid catalyzed or free radical process was found to be responsible for these isomerizations. 

Steroid and stilbene derivatives e.g. rrans-stilbene metabolites [16]... 

A breakthrough in iron-catalyzed asymmetric epoxidation of aromatic alkenes using hydrogen peroxide has been reported by our group in 2008. Good to excellent isolated yields of aromatic epoxides are obtained with ee-values up to 97% for stilbene derivatives using diphenylethylenediamines 9 as ligands (Scheme 5) [45, 46]. 

The pharmacological potential of this tree is unexplored. Note that Cryptocarya species are very interesting, as they have the tendency to elaborate a series of stilbenes derivatives known as a-pyrones (112,113). The neuropharmacological potential of such... 

For example, stilbene oxygenases, which cleave the interphenyl a,P-double bond of stilbene derivatives, are known to be members of the CCO family of enzymes that act on substrates other than... 

Marasco, E. and C. Schmidt-Dannert (2008). Identification of bacterial carotenoid cleavage dioxygenase homologs that cleave the interphenyl u,(J double bond of stilbene derivatives via a monooxygenase reaction. Chembiochem. 9(9) 1450-1461. 

Kool and co-workers recently reported a multicolor set of water-soluble dyes synthesized through the combination of three to five individual fluorophores assembled on a DNA-like backbone [94, 95]. As a continuation of their previous works on various DNA analogs [96-99], they synthesized the oligodeoxyfluoro-side (ODF) with seven fluorescent monomers, such as pyrene, perylene, dimethy-laminostilbene, and three stilbene derivatives, and they assembled these fluorescent DNA monomers into oligofluor chains using a DNA synthesizer (Fig. 26). Using... 

Very few examples of singlet n-n dimerizations are reported, the reactions of 2-butenes in Eqs. 36 and 37 being examples with observable stereochemistry. The reactions are stereospecific in agreement with theory. The unsensitized reactions of styrene 115> and some stilbene derivatives 116> may also proceed via excited states, Eq. 47 and... 

Synthesis of the phenyl derivative (138) was also described by Simoni et al. [60] and employs the same synthetic strategy as for the pyridine derivative (137) described in Scheme 34. No biological activity was reported for this compound, but it was included in order to provide a broader coverage of stilbene derivatives. 

There are considerably fewer examples of heterocyclic chalcone analogs of combretastatin than in the heterocyclic stilbene derivative category. Of these,... 

Since their commercial introduction during the 1940s as components of proprietary detergents and laundry preparations, these products have found extensive usage in the whitening of paper and textile materials. Disperse FBAs are available for whitening hydrophobic fibres and solvent-soluble FBAs impart fluorescence to oils, paints, varnishes and waxes. Approximately 75% of commercially established FBAs are stilbene derivatives with inherent substantivity for paper and cellulosic textiles, but the remainder come from about twenty different chemical classes. These include aminocoumarins (6%), naphthalimides (3%), pyrazoles and pyrazolines (each about 2%), acenaphthenes, benzidine sulphones, stilbene-naphthotriazoles, thiazoles and xanthenes (each about 1%). FBAs of these and other chemical types are discussed in detail in Chapter 11 of Volume 2. 

Uchiyama [11] has given details of a procedure he developed for the isolation and determination of down to 0.2mg kg 1 of fluorescent whitening agents in extracts of bottom deposits. The fluorescent whitening agents were sodium salts of a sulphonated stilbene derivative and this was measured by fluorescence (excitation 370nm, emission 405nm) with the use of tctra-w-butyl ammonium hydroxide. 

W. Rettig and W. Majenz, Competing adiabatic photoreaction channels in stilbene derivatives, Chem. Phys. Lett. 143, 335-341 (1989). 

---