Cinnamate 4- 2- ethenyl

See Styrene/butadiene polymer Ethenylbenzene, polymer with 2-propenamide. See Styrene/acrylamide copolymer Ethenylbenzenesulfonic acid, sodium salt, homopolymer 4-Ethenylbenzenesulfonic acid sodium salt, homopolymer. See Sodium polystyrene sulfonate 4-Ethenylcyclohexene 4-EthenyM -cyclohexene. See 4-Vinylcyclohexene Ethenyidimethoxymethylsilane. See Vinylmethyidimethoxysilane 1 -Ethenyl-1,5-dimethyl-4-hexenyl benzeneacetate. See Linalyl phenylacetate 1 -Ethenyl-1,5-dimethyl-4-hexenyl 3-phenyl-2-propenoate. See Linalyl cinnamate Ethenyl ethanoate. See Vinyl acetate 6-Ethenyl-6-(methoxyethoxy)-2,5,7,10-tetraoxa-6-silaundecane. SeeVinyltris(2-methoxyethoxy) silane... 

As a typical example of topochemically prepared polymers, the nmr speetrum of the polymer derived from ethyl 4-[2-(2-pyrazyl)ethenyl]-cinnamate [l OEt] crystals by reaction (2), and the X-ray diffraction patterns of the same monomer and polymer are illustrated in Figs 1 and 2 (Hasegawa et al., 1989a). 

Fig. 5 Topochemical behaviour and crystal structure of methyl a-cyano-4-[2-(4-pyridyl)ethenyl]cinnamate (2 OMe).

Methyl 4-[2-(ethylthiocarbonyl)ethenyl]cinnamate (3 SMe) crystallizes into a typical a-translation-type packing structure in which the distances between the ethylenic double bonds are 3.988 A and 4.067 A, respectively. However, the 3 SMe crystal is entirely photostable even though it should be photoreactive based on the topochemical rule (Sukegawa, 1991). Several examples of exceptionally photostable diolefin crystals have been found in compounds having a thioester moiety. Such anomalous behaviour of crystals such as 2 OMe and 3 SMe cannot be explained simply in terms of the topochemical rule since this rule involves only the positional relationship between the reactive olefin pair. 

Similar behaviour has been observed in the photoreaction of methyl a-cyano-4-[2-(2-pyridyl)ethenyl]cinnamate (7 OMe) crystals in which the yield of [2.2] paracyclophane reached 65% on irradiation at — 78°C (see Scheme 10 p. 153) (Hasegawa et al., 1989b). From the crystal structure analysis of the same type of [2.2] paracyclophane, which is topochemically derived from alkyl a-cyano-4-[2-(4-pyridyl)ethenyl]cinnamate crystals, a highly strained molecular shape is confirmed in which two phenylene rings are severely bent (Maekawa et al., 1991b). 

Ethyl a-cyano-4-[2-(2-pyridyl)ethenyl]cinnamate (7 OEt) also crystallizes with /3-centrosymmetric-type packing yielding photoreactive crystals and, upon photoirradiation (>410 nm), is converted into the /3-hetero-type dimer (7 OEt-dimer) nearly quantitatively. The 7 OEt-dimer (space group PT, triclinic) has the structure which is predicted from the crystal structure of 7 OEt (space group PT, triclinic). 

Ethyl 4-[2-(4-pyridyl)ethenyl]cinnamate (5 OEt) crystals (j8-type packing) gives an optically active dimer through a topochemical [2-1-2] photocycloaddition (enantiomeric effect >90%). The asymmetric induction is ex-... 

It may be suspected that the genuinely topotactic (as secured by the molecular precision of the AFM [18]) photodimerization of 2-benzyl-5-benzyli-denecyclopentanone [118] might be a good candidate for a quantitative preparative photo dimerization to give the head-to-tail anti-[2+2] dimer. Early quantitative solid-state [2-1-2] photodimerizations (most of the published mechanistic interpretations of which can no longer be accepted) are listed in [110]. These deal with the anti dimerization of acenaphthylene-1,2-dicarboxylic anhydride, the head-to-head syn dimerization of acenaphthylene-1-carboxylic acid, the syn dimerization of 5,6-dichloroacenaphthylene, and the thermally reversible head-to-tail anti dimerization of seven ( )-2,6-di-f-butyl-4-(2-aryl-ethenyl)pyrylium-trifluoromethanesulfonates. All of these reactions proceed fully specific. On the other hand, quantitative photoconversions of a 1 1 mixed crystal of ethyl and propyl a-cyano-4-[2-(4-pyridyl)ethenyl]cinnamates gives mixtures of diesters with one (A>410 nm) or two cyclobutane rings (no cutoff filter). 

Keywords a-cyano-4-[2-(2-pyridyl)ethenyl]cinnamate, [2+2]photodimerization, cyclobutane, [2.2]paracyclophane... 

Hasegawa et al. reported another example of a [2 + 2] asymmetric transformation in a chiral crystal. [16] Ethyl 4-[2-(pyridyl)ethenyl] cinnamate 15 crystallizes in a chiral space group Phhh and upon irradiation yields a chiral dimer 16 with 92-95% ee. 

Hasegawa et al. have taken advantage of the high order attending photopolymerization of 9 to produce a novel crystal consisting of an ordered arrangement of two polymers [100]. Compound 9 and ethyl 4-[2-(2-pyrazinyl)-ethenyl]-cinnamate (15, Scheme 12) form co-crystals from benzene with a composition... 

Photodimerization of the Methyl q-cyano-4-[2-(2-pyridyl)ethenyl]-cinnamate III (2-pyridyl, X CN, Y COOMe) Crystal (13c). In the course of the photoreaction of the crystal of III (2-pyridyl, X CN, Y COOMe), the UV absorption band at 365 nm decreased and a new absorption peak appeared at 313 nm. In addition, clear isosbestic points were seen in the spectra at 258 and 329 nm. The photoreaction was fast, and, finally, the TLC of the photoproduct showed a single spot. These spectral data and the results of TLC analysis indicate the progress of a single reaction on photoirradiation of the crystal. 

The use of crystal-to-crystal [2+2] photodimerizations as a means to construct crystalline polymers has been pioneered by Hasegawa and co-workers [32]. To construct the polymers, reactants with two double bonds in the form of 1,4-divinyl-benzenes, such as methyl 4-[2-(4-pyridyl)ethenyl]cinnamate (Scheme 2.3.2) were employed [33]. One-dimensional chains composed of repeat units of cyclobutane... 

---