Formation of bicyclo [3.2.1]oct-2-en-8-ones and 1-hydroxy-dihydrosemibullvalenes from the meta-photocycloaddition of cyclopentene to phenols

19F NMR Ligand Perturbation Studies on 6,7-Bis(trifluoromethyl)-8-ribityllumazine-7-hydrates and the Lumazine Synthase Complex ofBacillussubtilis.Site-Directed Mutagenesis Changes the Mechanism and the Stereoselectivity of the Catalyzed Haloform-Type Reaction

“…Initializing the elimination reaction by the interaction of the trifluoromethyl group with the arginine side chain seems to be a novel mechanism. The formation of intramolecular H-bonds between trifluoromethyl groups and hydroxyl groups resulting in conformational stabilization has been reported in the case of 2-trifluoromethylphenol. − Intramolecular hydrogen bonding between a hydroxyl group and a trifluoromethyl group also influenced the specificity of photocycloadditions in 1-hydroxy-dihydrosemibullvalenes . However, there is no information about hydrogen bonding of an amino acid side chain with a fluorinated ligand available as suggested in the present study.…”

“…[17][18][19] Intramolecular hydrogen bonding between a hydroxyl group a trifluoromethyl group also influenced the specificity of photocycloadditions in 1-hydroxy-dihydrosemibullvalenes. 20 However, there is no information about hydrogen bonding of an amino acid side chain with a fluorinated ligand available as suggested in the present study.…”

Intramolecular Photochemical Reactions of Bichromophoric 3-(Alkenyloxy)phenols and 1-(Alkenyloxy)-3-(alkyloxy)benzene Derivatives. Acid-Catalyzed Transformations of the Primary Cycloadducts

“…Three types of cycloaddition reactions are usually observed between photochemically excited benzene derivatives and alkenes. − Depending on the relative redox potentials and on the substitution pattern of the two reaction partners, [2 + 2], [2 + 3], or [2 + 4] cycloadditions can be observed. , In case of alkoxy-substituted benzene derivatives, [2 + 2] addition and [2 + 3] cycloaddition (meta-cycloaddition), the most frequent process, can have considerable interest for organic synthesis of polycyclic skeletons (e.g., triquinanes). , Intramolecular [2 + 2] photocycloaddition of (alkenyloxy)benzenes have been reported to give unstable intermediates in thermal or photochemical equilibrium. , Until recently, little attention had been paid to the photochemistry of (alkenyloxy)phenols, and only a few examples of intermolecular [2 + 2] cycloaddition of alkenes to phenols have been reported in the literature . Additionally, one example of an intramolecular [2 + 2] photocycloaddition, a photocyclization of allylphenols, and a di-π-methane photorearrangement were also described …”