Effect of ring size on photoisomerization properties of stiff stilbene macrocycles

• Sandra Olsson,
• Óscar Benito Pérez,
• Magnus Blom and
• Adolf Gogoll

Beilstein J. Org. Chem. 2019, 15, 2408–2418, doi:10.3762/bjoc.15.233

• Shimadzu UV-1650PC spectrophotometer using 10 mm quartz cuvettes. Photoisomerizations were performed using an Oriel 1000 W Xe ARC light source equipped with a band pass filter 10BPF10-300 or 10BPF10-280 (Newport). Computational details The DFT calculations on the stiff stilbene macrocycles were performed

• , 298, 252 nm. Photoisomerizations (followed by NMR spectroscopy) CDCl3 solutions of products (Z)-1d and stiff stilbene were irradiated after degassing by argon bubbling for 15 min. As reaction vessels, 5 mm NMR tubes, type 5Hp, 178 mm were used. The course of isomerization was assessed by 1H NMR

• spectroscopy. Photoisomerizations (followed by UV–vis spectroscopy) CHCl3 solutions of products (Z)-1d and stiff stilbene were irradiated after degassing by argon bubbling for 15 min. As reaction vessels, 10 mm quartz UV–vis cuvettes were used. The course of isomerization was assessed by UV–vis spectroscopy

Cycloheximide congeners produced by Streptomyces sp. SC0581 and photoinduced interconversion between (E)- and (Z)-2,3-dehydroanhydrocycloheximides

• Li Yang,
• Ping Wu,
• Jinghua Xue,
• Huitong Tan,
• Zheng Zhang and
• Xiaoyi Wei

Beilstein J. Org. Chem. 2017, 13, 1039–1049, doi:10.3762/bjoc.13.103

• photoisomerizations of compounds with this kind of chromophore had been rarely reported. For better understanding the insights into this reaction, we conducted theoretical investigation using the truncated structures 2a and 3a (Figure 1). At first, the lowest-energy geometries of 2a and 3a in MeOH in the ground (S0

The chemical behavior of terminally tert-butylated polyolefins

• Dagmar Klein,
• Henning Hopf,
• Peter G. Jones,
• Ina Dix and
• Ralf Hänel

Beilstein J. Org. Chem. 2015, 11, 1246–1258, doi:10.3762/bjoc.11.139

• is known about their basic photochemical reactions, such as photoisomerizations and/or photoadditions. For the unsubstituted hydrocarbons, this is not surprising in view of their general instability and the difficulty of obtaining pure diastereomers. With our stabilized oligoenes in hand, we started

• transformations. The first two processes involved photoisomerizations. It is well known that E/Z-isomerizations take place readily in oligoenes, even when daylight is used for photoexcitation. However, rather than isomerizing to 49, a mixture of diastereomers, 19 remained unchanged when irradiated with a daylight

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Cyclodextrin nanosponge-sensitized enantiodifferentiating photoisomerization of cyclooctene and 1,3-cyclooctadiene

• Wenting Liang,
• Cheng Yang,
• Masaki Nishijima,
• Gaku Fukuhara,
• Tadashi Mori,
• Andrea Mele,
• Franca Castiglione,
• Fabrizio Caldera,
• Francesco Trotta and
• Yoshihisa Inoue

Beilstein J. Org. Chem. 2012, 8, 1305–1311, doi:10.3762/bjoc.8.149

• of Chemistry, Materials and Chemical Engineering “G. Natta” – Politecnico di Milano, Piazza L. Da Vinci 32, 20133 Milano, Italy Department of Chemistry, University of Torino, Via P. Giuria 7, 10125 Torino, Italy 10.3762/bjoc.8.149 Abstract Enantiodifferentiating geometrical photoisomerizations of (Z

• ; pKa1 = 2.98 and pKa2 = 5.28 for phthalic acid) [45] will drive out the shallowly included PM from the cavity but still keep it near the portal with the short ester linker, orienting the 1La transition in the more negative region of the sector rule (parallel to the portal plane). Photoisomerizations of

• ). Enantiodifferentiating photoisomerizations of 1Z and 2ZZ sensitized by β- and γ-cyclodextrin nanosponges (CDNSs) cross linked by pyromellitic dianhydride (PDA). Representative enantiodifferentiating photosensitization of 1Z and 2ZZ with conventional and supramolecular photosensitizers. Enantiodifferentiating

Intraannular photoreactions in pseudo-geminally substituted [2.2]paracyclophanes

• Henning Hopf,
• Vitaly Raev and
• Peter G. Jones

Beilstein J. Org. Chem. 2011, 7, 658–667, doi:10.3762/bjoc.7.78

• : paracyclophanes; photoadditions; photoisomerizations; proximity effects; topochemical reaction control; vinylcyclopropanes; X-ray structural analysis; Introduction Photodimerizations of crystalline aromatic or olefinic compounds are among the oldest known organic photoreactions. In this type of reaction the

• paracyclophanes not be observed, this would not necessarily constitute a proof against diradical(oid) intermediates in these reactions. However, if derivatives such as 21 were among the photoproducts the involvement of radicals in the photoisomerizations would be indicated. We therefore reacted the bis-aldehyde 9