Intramolecular bridges formed by photoswitchable click amino acids

• Christian Hoppmann,
• Ronald Kühne and
• Michael Beyermann

Beilstein J. Org. Chem. 2012, 8, 884–889, doi:10.3762/bjoc.8.100

• light-induced click reaction of our PSCaa occurs predominantly in the cis state that is formed simultaneously due to the photoisomerization at λ = 365 nm. Recently, the concept of photoswitchable click amino acids has been applied to the polypeptide hormone urocortin, the helical fold of which was

• the study of this effect. Irradiation of the reaction mixture at λ = 365 nm for 45 min induces not only the thiol–ene click reaction but simultaneously the trans-to-cis photoisomerization. Under these conditions the formation of the intramolecular bridge resulted in click product 3 with i,i+4 helical

• click product 5 at high GSH concentrations and the intramolecular click product 3 at decreasing GSH concentrations. Photoisomerization of the photoswitchable click amino acid 2-amino-3-(4-((3-vinylphenyl)diazenyl)phenyl)propanoic acid. Thiol–ene click reaction of PSCaa with cysteine within the helical

meta-Oligoazobiphenyls – synthesis via site-selective Mills reaction and photochemical properties

• Raphael Reuter and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2012, 8, 877–883, doi:10.3762/bjoc.8.99

• biphenyl restores the photoisomerization properties (Figure 1) [18][19]. In a related example by Samanta and Woolley a similar compound was presented featuring anchoring groups for biological applications (Figure 1) [20]. In another study the team of Hecht synthesized oligomers separated by alkynyl linkers

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

• Braunschweig, Germany, Fax: +49 531 / 391 5387 10.3762/bjoc.7.78 Abstract The photoisomerization of the pseudo-geminal tetraene 11 furnishes the cyclooctadiene derivatives 13 and 15 with a completely new type of molecular bridge for a [2.2]paracyclophane which promise many interesting novel applications; the

• same is true for the photoisomerization of 22 to 23 and 24. The structures of these new hydrocarbons were established by X-ray crystallography and spectroscopic analysis; among the noteworthy structural features of 13 and 15 are unusually long carbon–carbon single bonds (>1.64 Å). Keywords

• prepare the biscyclopropane analog of 11, the bisvinylcyclopropane 19 (or one of its cis-isomers) and subject this presumably strained hydrocarbon to our photocyclization conditions. Of course, this system also has various options to react, among them the photoisomerization to a mono- or all-cis

Silica- bound benzoyl chloride mediated the solid- phase synthesis of 4H-3,1-benzoxazin- 4-ones

• Kurosh Rad-Moghadam and
• Somayeh Rouhi

Beilstein J. Org. Chem. 2009, 5, No. 13, doi:10.3762/bjoc.5.13

• ], photoisomerization of 2-arylisatogen [25], and cyclocondensation of anthranilic acid with orthoesters [26]. Meanwhile, the cyclodehydration of N-acylanthranilic acids in refluxing acetic anhydride has been the prevalent method used for production of 4H-3,1-benzoxazin-4-ones. However, use of traditional dehydrating