2,025 research outputs found
Using water, light, air and spirulina to access a wide variety of polyoxygenated compounds
A new set of completely green methods utilising air, light,
water and spirulina to transform readily accessible furan
substrates into a diverse range of synthetically useful polyoxygenated motifs commonly found in natural products is
presented herein
Oxidation of Monolayers of Partly Converted Dimethoxy-Substituted Poly(p-phenylenevinylene) Precursor Polymers at the Air-Water Interface
We observed that the poly(p-phenylenevinylene) units in Langmuir monolayers of partly converted dimethoxy-substituted poly(p-phenylenevinylene) precursor polymers oxidize at the air-water interface. This reaction even happened in the dark and therefore can not be attributed to a photooxygenation reaction with singlet oxygen. We assume that ground-state triplet oxygen is polarized at the air-water interface and forms a weakly bound complex with the double bond to give a reactive intermediate state, which lowers the activation energy of the oxidation reaction. The air-water interface thus works as a catalyst in this reaction.
Photochemical behavior of the drug atorvastatin in water.
Atorvastatin undergoes a self-sensitized photooxygenation by sunlight in water. The main photoproducts, isolated by chromatographic
techniques, have been identified by spectroscopic means. They present a lactam ring arising from an oxidation of pyrrole ring and an
alkyl/aryl shift. A mechanism involving singlet oxygen addition and an epoxide intermediate is suggested
Dye-sensitized Photooxygenation of furanosyl Furans; Synthesis of a new Pyridazine C-Nucleoside
The dye-sensitized photooxygenation of furanosyl furans easily affords C- or O-glycosides with cis-R,-unsaturated 1,4-dioxo aglycones. The reaction, performed on a ribofuranosyl furan, provides a useful new entry to a novel pyridazine C-nucleoside that can be achieved through a simple one-pot procedure
Photooxidations of 2-(γ,ε-Dihydroxyalkyl) Furans in Water: Synthesis of DE-Bicycles of the Pectenotoxins
Photooxygenations of 2-(γ,ε-dihydroxyalkyl) furans in H2O followed by in situ reduction and ketalization affords, in one synthetic operation, DE-bicyclic ketals of the pectenotoxins
Photooxygenation of furans in water and ionic liquid solutions
Photooxygenation of differently functionalized furans is investigated in aqueous solutions and in
ionic liquids [emim]Br and [bmim]BF4. The reaction is generally selective and the final products
derive from rearrangement of the intermediate endoperoxides, depending mainly on the polarity
and/or nucleophilic nature of the solvent
Photooxygenation of Non-Aromatic Heterocycles
Photooxygenation of non-aromatic heterocycles and cyclic compounds containing non-usual heteroatoms, namely silicon, germanium and tellurium has been reviewed. All three types of photooxygenation (Types I-III) can take place. Moreover the heteroatom can be frequently involved endorsing electron-transfer reactions which turn out to be the main pathways, even in singlet oxygen oxygenation. A vast collection of novel and unexpected products are often formed, sometimes in a stereocontrolled manner
Versuche zur asymmetrischen Redox-Disproportionierung von meso-Peroxiden. Neue Chrom(III)-und Organokatalysatoren für die asymmetrische Hetero-Diels-Alder Reaktion
Theoretical study on the photooxygenation and photorearrangement reactions of 3-hydroxyflavone
The mechanisms of three photodegradation reactions of 3-hydroxyflavone – its photosensitized oxygenation, photooxygenation with 3O2 and photorearrangement into an indanedione derivative – have been investigated by computing the free energy profiles.</p
Phototransformation Products of Tamoxifen by Sunlight in Water. Toxicity of the Drug and Its Derivatives on Aquatic Organisms
Transformation of tamoxifen has been observed in water by prolonged sunlight irradiation. The main photoproducts, isolated by
chromatographic techniques, have been identified by spectroscopic means. Photoisomerization, photocyclization and, to a lesser extent,
photooxygenation appear to be involved in the degradation of the drug. The acute and chronic toxicity of the parent drug and its photoproducts
were tested on non-target aquatic organisms (Brachionus calyciflorus, Thamnocephalus platyurus, Daphnia magna and Ceriodaphnia
dubia). Exposure to all the compounds induced mainly chronic effects without significant differences among the parental and
derivative compounds
- …
