Pyridylsubstituierte Cyclobutane durch Photodimerisierung von Azastilbenen

Horner, Michael; Hünig, Siegfried

doi:10.1002/jlac.198219820619

Cited by 22 publications

(10 citation statements)

References 66 publications

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“…Notably, the cyclobutane derivatives 4b and 4c were not persistent in solution for extended periods of time. As already shown for several cyclobutane derivatives, these compounds tend to isomerize to the corresponding rttt isomers [83][84][85][86].…”

Section: Photocycloaddition Reactionssupporting

confidence: 58%

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

Kölsch¹,

Ihmels²,

Mattay³

et al. 2020

Beilstein J. Org. Chem.

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It was demonstrated that styrylquinolizinium derivatives may be applied as photoswitchable DNA ligands. At lower ligand:DNA ratios (≤1.5), these compounds bind to duplex DNA by intercalation, with binding constants ranging from K b = 4.1 × 104 M to 2.6 × 105 M (four examples), as shown by photometric and fluorimetric titrations as well as by CD and LD spectroscopic analyses. Upon irradiation at 450 nm, the methoxy-substituted styrylquinolizinium derivatives form the corresponding syn head-to-tail cyclobutanes in a selective [2 + 2] photocycloaddition, as revealed by X-ray diffraction analysis of the reaction products. These photodimers bind to DNA only weakly by outside-edge association, but they release the intercalating monomers upon irradiation at 315 nm in the presence of DNA. As a result, it is possible to switch between these two ligands and likewise between two different binding modes by irradiation with different excitation wavelengths.

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Section: Photocycloaddition Reactionssupporting

confidence: 58%

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

Kölsch¹,

Ihmels²,

Mattay³

et al. 2020

Beilstein J. Org. Chem.

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“…For the photodimerization of styrylpryidines, see: Horner & Hü nig (1982); Quina & Whitten (1975); Zhang, Zhang, Zheng, Shen & Zhuang (2000). For the single-crystal structures of tetraaryl cyclobutanes and related molecules, see: Busetti et al (1980); Coe et al (2005); Li et al (2007); Zhang et al (1998); Zhang, Zhang, Zheng, Wang & Zhao (2000); Zhuang & Zheng (2002).…”

Section: Related Literaturementioning

confidence: 99%

r-1,t-3-Bis[4-(dimethylamino)phenyl]-c-2,t-4-bis(pyridin-4-yl)cyclobutane

Zhang

Zhuang

2014

Acta Cryst E

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The title compound, C30H32N4, was synthesized by the photodimerization of trans-4-{2-[4-(dimethylamino)phenyl]ethenyl}pyridine in benzene upon irradiation with UV light. This photodimer has a puckered cyclobutane ring with the four aryl substituents in an r-1,t-2,c-3,t conformation. The puckering angle of the cyclobutane ring is 32.22 (7)°, which is the largest among reported tetraaryl-substituted cyclobutanes. In the crystal, the molecules form a hollow, one-dimensional structure extending parallel to the c axis via two different pairs of C—H⋯π interactions.

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“…Photolysis reactions in the solid state produce results markedly different from those in solution, with the styrylpyridine free bases forming only very low yields of cyclobutanes (<5%) and percent conversion to the dimer from the pyridinium salt varying greatly depending on the alkyl group and counterion used. 27 , 28 While X-ray crystal structures were not obtained for the majority of these azastilbenes, the significant effect of counteranions on the dimerization yield suggests that changes in molecular packing might be at play and thus might be explained by the topochemical postulate. This presumption was reinforced by results with 1,2-bis(4-pyridyl)ethylenes and 1,2-bis(2-pyrazinyl)ethylenes, which demonstrated an inverse correlation between the distance separating the double bonds and the rate of dimerization, 30 and more recently by the solid-state photolysis of a wide array of 4-stilbazole HCl salts.…”

Section: Introductionmentioning

confidence: 99%

π–π Interaction Energies as Determinants of the Photodimerization of Mono-, Di-, and Triazastilbenes

2014

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We describe the quantitative [2 + 2] photocycloaddition of crystalline trans-2,4-dichloro-6-styrylpyrimidine to produce the corresponding htt r-ctt cyclobutane dimer, and we present 1H NMR analysis of the photolysis of this and six other mono-, di-, and triazastilbenes in solid and solution states. Density functional (M06-2X) and correlated ab initio (MP2) calculations were used to obtain interaction energies between two monomers of each azastilbene. These energies mirror the relative polarization of the stilbene moieties and can be quantitatively correlated with the rate of reaction and selective formation of the htt r-ctt dimers. In the solid state, poor correlation is observed between interaction energy and reactivity/selectivity. This lack of correlation is explained through X-ray analysis of the azastilbene monomers and is shown to be in accordance with the principles of Schmidt’s topochemical postulate. Conversely, in solution there is a strong positive correlation (R2 = 0.96) between interaction energies and formation of the htt r-ctt dimer. These results are the first to show this correlation and to demonstrate the utility of calculated interaction energies as a tool for the prediction of stereo- and regioselectivity in solution-state stilbene-type photocycloadditions.

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Pyridylsubstituierte Cyclobutane durch Photodimerisierung von Azastilbenen

Cited by 22 publications

References 66 publications

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

r-1,t-3-Bis[4-(dimethylamino)phenyl]-c-2,t-4-bis(pyridin-4-yl)cyclobutane

π–π Interaction Energies as Determinants of the Photodimerization of Mono-, Di-, and Triazastilbenes

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