-At-the-same-time-the-phototransformation-of-such-systems-proceeds-exclusively-in-the-direction-of-the-contraction-of-the-pyranone-ring-leading-to-unstable-hydroxydiketones-s

For the first time the possibility of isolation of the resulting α-hydroxydiketones in pure form was demonstrated. Wherein, it was shown that relatively low stable α-hydroxydiketones can be trapped by reaction with 1,2-phenylenediamine. The general method for the preparation of the corresponding quinoxalines on the basis of the aforementioned condensation was implemented. It was demonstrated that the studied photoreaction does not depend on the type of pyrazole bridge. 6-butyl-n-hydroxynaphthimide trifluoromethanesulfonic acid in Medicinal Chemistry of three of synthesized products were established by X-ray Efficient Photodissociation of Anions from Benzoyl-Functionalized Ferrocene Spectroscopic and photochemical studies of several benzoyl-functionalized ferrocene complexes in nonaqueous solvents are reported. Bands observed above 300 nm in the electronic absorption spectrum of the unsubstituted complex, wavelengths and intensify upon introduction of a benzoyl group into one or both cyclopentadienide rings.

Such behavior suggests that these transitions have acquired some charge-transfer character. Visible-light (546 nm) irradiation of alpha-cyanopropionate causes ring-metal cleavage to produce the and 08 in ethyl alpha-cyanopropionate and is unaffected by the presence of ppm). 1,1'-Dibenzoylferrocenes containing substitutents on both phenyl rings similar to that of III, while monobenzoylferrocenes are appreciably less photoreactive. A mechanism that accommodates the photochemical behavior of benzoyl-functionalized ferrocene complexes is discussed. In addition, a previous suggestion concerning the role of III in the photoinitiated anionic polymerization of an alpha-cyanoacrylate monomer is reconsidered in light of the Surface-Induced Keto-Enol Tautomerization of DNA Base Molecules and Consequent [4 + 2]-like Cycloaddition on Si(111)7×7.Adsorption and film growth of deoxyribonucleic acid (DNA) base molecules (cytosine, guanine, thymine, and adenine) on Si(111)7×7 have been studied by combining X-ray photoelectron spectroscopy (XPS) with ab initio calculations based on the density functional theory (DFT). Seebio Photosensitive Acid Generator and keto-enol tautomerization are revealed by the O 1s, N 1s, and C 1s XPS spectra of the O-containing DNA bases: cytosine, guanine, and thymine.

While the carbonyl group-containing keto tautomer is more stable in a thick film and in powder, the hydroxyl group-containing enol tautomer is found at the interface. The keto-enol tautomerization, as induced by the reactive Si(111)7×7 surface, leads to the formation of a conjugated aromatic six-membered ring with a delocalized π electron system and to the consequent [4 + 2]-like cycloaddition between the enol tautomer and the 7×7 surface. The DFT calculation suggests that the enol tautomer exhibits a kinetic advantage over the keto one for the [4 + 2]-like cycloaddition. Among the several plausible pathways for the cycloaddition provided by the enol tautomer, the experimentally determined one involves a ring N and ring C atom (a polar pair), rather than two ring C atoms (a nonpolar pair), to better match the polar Si adatom-restatom pair of the 7×7 surface. Furthermore, the reacted ring C atom does not have any attached terminal functional group (e.g., -NH2 and -OH).

Further deposition leads to continuous film growth in the keto tautomeric form for cytosine and guanine. For the only O-free DNA base molecule, adenine, dative bonding N → Si, rather than the [4 + 2]-like cycloaddition, is observed on the 7×7 surface. Of the four DNA base molecules, adenine is also the only one with its aromaticity maintained when adsorbed on the Si(111)7×7 surface. A reactive surface like the 7×7 surface could therefore provide a new control to trigger tautomerization that is often 4,6-Dichloro-5-Nitrobenzofuroxan: Different Polymorphisms and DFT Investigation Center, Russian Academy of Sciences, Akad. Arbuzov st. 8, 420088 Kazan, Russia.Russian Academy of Sciences, Lobachevskogo st.

2/31, 420111 Kazan, Russia.Analysis", Korkyt Ata Kyzylorda University, Aitekebie str. 29A, Kyzylorda National Research Technical University, 10 Karl Marx Str., 420111 Kazan, Russia.Università di Bologna, Viale del Risorgimento 4, 40136 Bologna, Italy.Bologna, Via Selmi 2, 40126 Bologna, Italy.This research focuses on the X-ray structure of 4,6-dichloro-5-nitrobenzofuroxan 1 and of some of its amino derivatives (4a, 4e, 4g, and 4l) and on DFT calculations concerning the nucleophilic reactivity of 1.

We have found that by changing the solvent used for crystallization, it is possible to obtain Moreover, the different torsional angles observed for the nitro group in 1 and in its amino derivatives (4a, 4e, 4g, and 4l) are strictly dependent on the steric hindrance of the substituent at C-4. DFT calculations on the course of the nucleophilic substitution confirm the role of the condensed furoxan ring in altering the aromaticity of the carbocyclic frame, while chlorine atoms strongly influence the dihedral angle and the rotational barrier of the nitro group. These results corroborate previous observations based on experimental kinetic data and give a deep picture of the reaction with amines, which proceeds via a "non-aromatic" nucleophilic substitution.