Selectivity in the photo-fries rearrangement of some aryl benzoates in green and sustainable media. Preparative and mechanistic studies

Irradiation of a series of p-substituted aryl 10 benzoates under N2 atmosphere in homogeneous and micellar 11 media was investigated by means of steady-state condition and 12 of time-resolved spectroscopy. A notable selectivity in favor of 13 the 2-hydroxybenzophenone derivatives was observed in 14 micellar media. The benzophenone derivatives were the 15 main photoproduct. On the other hand, in homogeneous 16 media (cyclohexane, acetonitrile, and methanol) the observed 17 product distribution was entirely different, viz. substituted 2- 18 hydroxybenzophenones, p-substituted phenols, benzyl and 19 benzoic acid were found. The binding constants in the 20 surfactant were also measured and NOESY experiments showed that the aryl benzoates were located in the hydrophobic core of 21 the micelle. Laser flash photolysis experiments led to the characterization of both p-substituted phenoxy radical and substituted 22 2-benzoylcyclohexadienone transients in homogeneous and micellar environment.Fil: Siano, Gastón. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Crespi, Stefano. Universita Degli Studi Di Pavia; ItaliaFil: Mella, Mariella. Universita Degli Studi Di Pavia; ItaliaFil: Bonesi, Sergio Mauricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; Argentina. Universita Degli Studi Di Pavia; Itali

Light and drugs: the photochemistry of fluoroquinolone antibiotics

Light-related adverse side-effects of drugs are now an important source of concern. In order that the mechanism underlying to such effects is recognised, an in-depth photochemical study must be carried out. The case of some fluoroquinolone antibiotics (norfloxacin, enoxacin, lomefloxacin) is discussed as a representative example. These drugs undergo heterolytic fragmentation of the C—F bond leading to aryl cations. Quantum yields in neutral water range from 0.001 to 0.5 depending on the charge transfer degree of the ππ* state. Lower values are obtained at both acidic and basic pH. There is indication that the excited state involved in most of this reactions is a relatively long-lived triplet. The aryl cations undergo intra- or intermolecular reactions, and are presumably involved in the reported photo-toxic effect

Synthesis and Biological Activity of Potential Antiviral Compounds Through 1,3-Dipolar Cycloadditions; Part 2: Nitrones, Nitrile Oxides and Imines, and Other 1,3-Dipoles

Prominent in the current stage of drug development, antiviral compounds can be efficiently prepared through cycloaddition reactions. This review reports the use of 1,3-dipolar cycloadditions of nitrones, nitrile oxides and imines and other 1,3-dipoles in the light of their application for the preparation of synthons in the design and synthesis of compounds that were tested for their antiviral activities against a variety of viruses. Since nitrile oxides represent valuable precursors of nitrosocarbonyl intermediates, their use in the synthesis of antiviral compounds is reported. The products obtained from these pericyclic reaction approaches were tested for their activities in terms of blocking the virus replication and the relevant biological data are highlighted

Photoinduced SET for the functionalization of alkanes

Thermochem. cycles show that deprotonation of alkane radical cations is an exothermic process, and indeed photoinduced SET between several alkanes and 1,2,4,5-tetracyanobenzene (TCB) is followed by efficient deprotonation of the radical cation with tertiary > secondary > primary selectivity; the alkyl radical is trapped by TCB- or, when present, by oxygen; when tetrachloro-p-benzoquinone is used in the place of TCB, the radical is further oxidized to the catio