4-Cyano-4 stilbene

The preparation of cyano-substituted styryl and stilbenyl compounds can be achieved38,39 by using sodium methoxide at room temperature. In this way, o-tolunitrile has been reacted with the anil of 2-(/>-formyl-phenyl)benzo[6]furan and / -chloroaniline (52) to give 2-(2-cyano-stilben-4 -yl)benzo[6]furan (53). 

SYNS BENZAL-(BENZYL-CYANID) (GERMAN) O BENZYUDENEPHENYLACETONITRILE a-CYANO-STILBENE a,p-DIPHENYLACRYLONITRILE F 2387 a-PHENYLCINNAMONITRILE a-(PHENYLMETH-YLENE)BENZENEACETONTrRILE a-STILBENE-CARBONITRILE USAFA-9789... 

Stilben-4-yl)naphthotriazoles (2) are prepared by diazotization of 4-amino-stilbene-2-sulfonic acid or 4-amino-2-cyano-4 -chlorostilbene, coupling with an ortho-coupling naphthylamine derivative, and finally, oxidation to the triazole. 

Lapouyade R, Czeschka K, Majenz W, Rettig W, Gilabert E, Rulliere C (1992) Photophysics of donor-acceptor substituted stilbenes. A time-resolved fluorescence study using selectively bridged dimethylamino cyano model compounds. J Phys Chem 96(24) 9643-9650... 

B. Jiang, S.-W. Yang, R. Niver, and W.E. Jones, Jr., Metalloporphyrin polymers bridged with conjugated cyano-substituted stilbene units, Synth. Met., 94 205-210, 1998. 

Bazan and co-workers [93] coupled four branches of stilbene chromophores to a central C atom, leading to tetrastilbenylmethane [C(STB)4, 46a] tetrakis (4-ferf-butylstyryIstiIbenyljmethane [C(f-BuSSB)4, 46b], and the higher homolo-gue tetrakis 4-[4 -(4"-terf-butyl-styryl)styryl]stilbenyl methane [C(4R—f-Bu)4, 46c]. For 46b, Tg is 190°C, and for 46c it is as high as 230°C. Tetrakis(4,4 -2,2-diphenyl-vinyl)-l,l -biphenyl]methane [C(DPVBi)4, 47a] and the cyano derivative 47b exhibit the glass transition at 142 and 174°C, respectively. Similar compounds to 46a and 46b have also been synthesized with silicon and adaman-tane as the tetrahedral center. 

Fig. 5a) does not correlate with the betaine HOMO (Fig. 5b), and it can be shown, therefore, that the thermal reactions are symmetry forbidden whereas photochemical reactions are symmetry allowed. Mechanistically, these reactions are analogous to the disrotatory ring opening of a-cyano-c/.s-stilbene oxide (450 - 451) which Huisgen and Markowski have demonstrated takes place thermally with a free energy of activation of 35.6 kcal mol at Clearly, although forbidden, these reactions are not... 

Ultraviolet irradiation of the methiodide or hydrochloride of 2-styryl-pyridine (XCIII) in the solid state results in transformation of the trans-isomers to the corresponding dimers (XCVa, b) on the other hand irradiation in benzene solution gives both isomerization and dimerization.309 Dimer (XCVa) was produced in low yield on irradiation of XCIII in the powdered form in the presence of air.308 This is in contrast to the reported stability of XCIII toward photodimerization.109 Similar dimerizations have been reported in the case of 2,4-dichloro-3-cyano-6-styrylpyridine,164 2-styrylquinaldine (XCV) and frans-4,4 -diguanyl-stilbene bis(2-hydroxyethane sulfonate) (stilbamidine) (XCIV).82,83... 

In parallel to this example, Lewis and coworkers have also observed inverse reactivity for electron transfer and cycloaddition efficiency in the interaction of trans-stilbene with unsaturated esters (52). This result is understandable if the exciplex, rather than the radical ion pair, arranges the olefins in the correct geometry for cycloaddition. Analogous results have also been reported in the (2+2) cross photoreaction of cyano-substituted stilbenes with dienes, where all possible regioisomers were formed, eq. 16 (53a) ... 

Such reactions have also been carried out on benzofurans carrying benzyl, fluoro, chloro, bromo, methoxy, cyano, and phenyl groups in the benzo ring. Substitution in the stilbene part of the molecule can also be obtained by the use of Schiff s bases derived from differing benzal-dehydes.26,28,29... 

The sensitization properties of porphyrin compounds have also been improved by introducing dendron groups to the cyano substituted meso-stilbene moieties (46, 47). The aggregation of porphyrin was efficiently suppressed by the bulky dendrons while the electron injection to the conduction band of TiC>2 was improved by the cyano groups. The overall energy transfer efficiency was promoted remarkably to 2.76% for a solid DSSC. This is an encouraging result for a porphyrin dye and it offers the potential for porphyrins as alternatives to ruthenium-based dyes in the DSSC [82]. 

As a preparative method the direct decarboxylation of olefinic acids is almost limited to the formation of styrenes and stilbenes from substituted cinnamic acids. Thermal decomposition of cinnamic acid gives styrene (41%). The yield is nearly quantitative if the reaction is carried out in quinoline at 220° in the presence of a copper catalyst. The yields of substituted styrenes where the aryl radical contains halo, methoxyl, aldehyde, cyano, and nitro groups are in the range of 30-76%. cis-Stilbene and cis-p-nitrostilbene are prepared in this way from the corresponding a-phenylcinnamic acids (65%). One aliphatic compound worthy of mention is 2-ethoxypropene, prepared by heating -ethoxycro-tonic acid at 165° (91% yield). The mechanism of acid-catalyzed decarboxylations of this type has been studied. Isomerization of the double bond from the a,/5- to the /5, y-position before decarboxylation very likely occurs in many instances. ... 

The stilbene-dihydrophenanthrene photocycllsatlon reaction continues to find synthetic applications. The tetra-oxygenated methyl phenanthrene skeleton (161) has been prepared by photocyclisation of the stilbene (162) aromatisation of the intermediate dihydrophenanthrene occurs by elimination of methanol. 2 nq photocyclisation was observed In the absence of the cyano group in this compound 2 although the closely related structures (163) and (164) are said to cyclise to the phenanthrenes (165) and (166). Triarylethylenes are important... 

Self-assembled monolayers of isomerizable compounds can give nst tc surfaces with switchable permeability, thus resulting in different interfacial electrochemistry for a diffusional redox probe. A self-assembled monolayer of 4-cyano-4 -(10-thiodecoxy)stilbene on a Au-electrode demonstrated a higher blocking effect for the [Fe(CN)g] electrochemistry when it was in... 

A self-assembled monolayer of 4-cyano-4 -(10-thiodecoxy)stilbene on a Au-electrode was shown to have different hydrophobicities. In the trans-(18a) and cis- (18b) isomeric states (Figure 7.25). When the monolayer is in the CIS-State (18b), the polar cyano-groups are hidden in the monolayer and the hydrophobic spacers are exposed to the solution, thus providing the hydrophobic properties of the interface. After irradiation of the monolayer (X > 350 nm), the ds-stilbene units are photoisomerized to the fmws-state (18a), and the polar cyano-groups are mainly exposed to the solution. In this case, the interface becomes more hydrophilic, and the monolayer displays markedly different wetting properties. This difference allows the photo-patterning of the surface. ... 

Wolf, M. O., and Fox, M. A. Photochemistry and surface properties of aslf-assembled monolayers of as-4-cyano-4 -(10-thiodeeoxy)stilbene and traMS-4-cyano-4 -(10-thiodc-coxy)stilbene on polycrystalhne gold./. Am. Chem. Soc. 1995,117, 1845-1846. 

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