Stilbenoids

Scheme 71 Improved synthesis of (E)-stilbenoids by olefin CM on a solid phase [154]...

Rettig W, Strehmel B, Majenz W (1993) The excited states of stilbene and stilbenoid donor-acceptor dye systems. A theoretical study. Chem Phys 173(3) 525-537... 

Gonzalez-Barrio R, Beltran D, Cantos E, Gil MI, Espin JC and Tomas-Barberan F A. 2006. Comparison of ozone and UV-C treatments on the postharvest stilbenoid monomer, dimer, and trimer induction in var. Superior white table grapes. J Agric Food Chem 54(12) 4222 t228. 

Stoddart has employed the anion-directed [3]pseudorotaxane assemblies described above to control the outcome of solid-state photodimerisation reactions of olefins [116]. A combination of supramolecular interactions (one of them being hydrogen-bonding to PF,) has been employed to pre-organize bis(dialky-lammonium) salts containing fraws-stilbenoid units (89) into the [3]pseudoro-taxane assembly 90 shown in Scheme 45. 

A crystalline sample of this supramolecular assembly was irradiated with UV light and the formation of the corresponding cyclobutane 91 with syn-anti-syn stereochemistry was observed. In contrast, the photodimerisation of trans-stilbenoid-bis(dialkylammonium) salts does not take place in the absence of the macro cycle, indicating the importance of pre-organizing the stilbenoid units (which requires the presence of the anion) for this solid-state reaction to occur. 

Combretastatin A-4 Stilbenoid phenol Combretastatin A-4 Oncology Tubulin binding Phase I/imil OXIGENE 644-650... 

Combretastatin A-1 Stilbenoid phenol OXi4503 Oncology Tubulin binding Phase I/II OXiGENE 652-657... 

Hernandez-Romero Y Rojas J-I, Castillo R, Rojas A, MataR, Spasmolytic effects, mode of action, and structure-activity relationships of stilbenoids from Nidema boothii, J Nat Prod 67 160—167, 2004. 

Gorham J, The Biochemistry of the Stilbenoids, Chapman Hall, London, 1995-... 

Fuendjiep, V. et al., Chalconoid and stilbenoid glycosides from Guibourtia tessmanii. Phytochemistry, 60, 803, 2002. 

Preisig-Mueller, R. et al.. Plant polyketide synthases leading to stilbenoids have a domain catalyzing malonyl-CoA C02 exchange, malonyl-CoA decarboxylation, and covalent enzyme modification and a site for chain lengthening. Biochemistry, 36, 8349, 1997. 

Bai, L. et al.. Four stilbenoids from Pleione bulbocodioides. Phytochemistry, 48, 327, 1998. 

Bletilla hyacinthina R. Br. B. striata (Thunb.) Reichb. Bai Ji (Amethyst orchid) (tuber) Gelatin, essential oil, stilbenoids, blespirol, blestrianol, phenanthrene glucosides, bisphenanthrene theres 33.434.491,492,493,494,495 Hemostatic, promotes leukocyte and platelet aggregation. Treat hematuria, blood splitting, primary hepatic carcinoma, antimicrobial. 

The most comprehensive studies on shape-persistent Hekates have been performed on stilbenoid star-shaped molecules. Structures and mesomorphic properties are collected in Table 1. Core building blocks with only one repeating unit per arm and one flexible chain 26a,b, 28a-d, 30a did not show any liquid crystal properties [56-58]. In the series of two chain derivatives 28e, 30b,c the formation of meso-phases depend on the core [57-59]. The electron deficient triazine and the dicyanopyridine building block induced obviously columnar mesophases. The pyridine derivative 30b showed only a crystalline phase [58]. In the series of nine chain stars 26c-g [60-62] and 28f-n [57], the compounds formed columnar phases depending on the chain length of the peripheral chains. Propyloxy chains are too short but hexyloxy and dodecyloxy chains are sufficient for the formation of liquid crystal phases by nanosegregation [60-62]. This can be rationalised by a dense... 

Scheme 1-64 points up one additional and important aspect to the problem of ferromagnetic coupling in dication diradicals. The stilbenoid compounds of Scheme 1-64 give N+ / N+ dication diradicals upon two consecutive one-electron oxidations (anodic or by means of NOPF6). The compound containing the methoxy group in the stilbenoid fragment has a half-life of up to two months, even under ambient conditions. This... 

Stilbenoid dendrimers are able to undergo aggregation. Depending upon the generation number, some of the pure substances form liquid-crystalline phases (Dha discotic hexagonal disordered phase Dra discotic rectangular disordered phase Dob discotic distorted phase). Differential scanning calorimetry (DSC) revealed phase transitions between 99°C and 0°C. 

Structurally, dendrimers of type 5 are best compared with rigid dendrimers made up of tolan building blocks. However, neither the form of aggregation observed in stilbenoid dendrimers, nor the phase behaviour or the photochemistry of these compounds have so far been found to occur in similar form in tolan systems. 

The interesting photophysics and photochemistry [37, 38] of stilbenoid compounds make them suitable for applications in materials science. In addition to well-established applications, such as in optical brighteners, others arise in light-emitting diodes (LED), in non-linear optics (NLO), and in optical imaging, storage, and switching techniques. 

Muller, M. Mauermann-Diill, H. Wagner, M. Enkelmann, V. Mullen, K. A cycloaddition-cyclodehydrogenation route from stilbenoids to extended aromatic hydrocarbons. Angew. Chem. Int. Ed. 1995, 34, 1583-1586. 

Suzuki-type coupling protocols were also evaluated as a method to prepare some related tetrahedral stilbenoid molecules and the optimal yields were achieved when using Pd(dppf)Cl2 as the catalyst. The cruciform materials prepared using this strategy are shown in Scheme 3.3. Compounds 5a and b were obtained as a mixture of cis and trans isomers as identified by high-performance liquid chromatographic (HPLC) analysis. Nevertheless, the mixtures were readily converted into the all-trans isomers by irradiating the dissolved samples with a mercury lamp. 

In the photoisomerization of l-(2-anthryl)-2-phenylethene [232-234] and l-(2-naphthyl)-2-phenylethene [235-237] 95, the s-cis/s-trans conformational isomerism plays an important role. (Z)-l-(2-Naphthyl)-2-phenyl-ethene is isolated in 70% yield in fluorenone-sensitized isomerization of the ( )-isomer (Sch. 39) [238,239]. The photochemical behavior of related (E)-stilbenoids (96-98) has been reported (Sch. 40) [240]. The direct and sensitized photoisomerizations of (Z)-styrylferrocene in benzene have also been reported [241]. 

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