Methyltriazolocoumarins: New furocoumarin isosters as potential photochemotherapeutic agents

A number of new methyltriazolocoumarins with a linear psoralen-like structure or an angular angelicin-like structure were synthetized. The syntheses were performed starting from the appropriate methylated 7-aminocoumarins which were nitrated, reduced and successively diazotized with concomitant cyclization to form the condensed triazolo ring. The new methyltriazolocoumarins show promising spectroscopic properties which are potentially predictive of their photochemical and photobiological behaviour.     

Base- and light-assisted synthesis of anthracenes from 3-allylnaphthalene-2-carbaldehydes

The synthesis of substituted anthracenes from naphthalene precursors is described. The key step involved heating ortho-allyl substituted naphthalene-2-carbaldehydes and potassium t-butoxide in DMF with concomitant irradiation from a high pressure mercury lamp to afford anthracenes in yields of 76-98%.     

13C NMR spectra and carbon-proton coupling constants of various methylangelicins

The ¹³C-nmr spectra of various methyl derivatives of angelicin are reported. The assignment of chemical shifts for all the C atoms has been achieved by using carbon-proton coupling constants, nuclear Overhauser effect consideration and shift effects caused by the introduction of methyl groups on various positions of the angelicin nucleus. Substituent effects on ¹³C chemical shifts and carbon-proton coupling constants are discussed.     

Determination of metal concentration in fat supplements for swine nutrition by atomic absorption spectroscopy

The presence of some essential and toxic metals in fat supplements for swine diet was investigated. Collected samples represented a relevant production of the Italian industry. In particular, some samples were enriched with antioxidants or waste cooking oils. The method for the determination of Ca, Cu, Cd, Fe, Mg, Mn, Ni, Pb, and Zn in fat samples was developed by means of a certified reference material (CRM 186) and a representative fatty sample (RFS). All samples were digested in closed vessels in a microwave oven and then analyzed by flame atomic absorption or graphite furnace atomic absorption spectrometry. The entire analytical method provided a satisfactory repeatability and reproducibility confirmed by agreement between the experimental recovery data obtained for the CRM 186 sample and, with the method of standard additions, for the RFS material. The samples generally showed a small amount of metals compared with the recommended daily intake for the essential elements. On the other hand, some samples contained a significant concentration, from an analytical point of view, of Cd, Ni, and Pb. Principal component analysis (PCA) was applied to inspect the experimental data obtained from samples analysis. Basically no differences were detected in terms of metal concentration among the fat supplements analyzed.     

Density and Volume Properties of the 2-Chloroethanol + 2-Methoxyethanol + 1,2-Dimethoxyethane Ternary Solvent System at Different Temperatures

The density of the 2-chloroethanol (CE) + 2-methoxyethanol (ME) + 1,2-dimethoxye- thane (DME) ternary mixtures has been measured at different temperatures ranging from –10 to 80^°C, and over the entire composition range. The experimental data have been used to check the validity of some relationships accounting for the dependence of the density on temperature and composition domains. Starting from the primary data, some derived quantities, such as excess molar volumes V ^E, partial molar volumes and partial excess molar volumes , have been obtained. In these mixtures, V ^E is always positive for the [CE(1) + ME(2)] binaries, while it is generally negative at all other experimental conditions, showing the greatest deviations along the binary axes corresponding to the binary subsystems in the sequence [CE(1) + DME(2)] < [CE(1) + ME(2)] < [ME(1) + DME(2)]. The results are compared and discussed to in terms of changes in molecular association and structural effects in these solvent systems.     

Insights into the Decomposition of Olefin Metathesis Precatalysts

The decomposition of a series of benzylidene, methylidene, and 3‐phenylindenylidene complexes has been probed in alcohol solution in the presence of base. Tricyclohexylphosphane‐containing precatalysts are shown to yield [RuCl(H)(H₂)(PCy₃)₂] in isopropyl alcohol solutions, while 3‐phenylindenylidene complexes lead to η⁵‐(3‐phenyl)indenyl products. The potential‐energy surfaces for the formation of the latter species have been probed using density functional theory studies.     

Stable tangential family germs and singularities of their envelopes

A tangential family is a system of regular curves emanating tangentially from another regular curve. We classify tangential family germs which are stable under deformations among tangential families and we study singularities of their envelopes. We also discuss some applications of our results to Differential Geometry. To cite this article: G. Capitanio, C. R. Acad. Sci. Paris, Ser. I 341 (2005).     

Difurocoumarins: Psoralen analogs as photochemotherapeutic agents

New tetracyclic psoralen‐like compounds have been synthesized, which are characterized by two furan rings angularly condensed on the coumarin nucleus and are therefore called difurocoumarins. This structural feature may favour the intercalation into the DNA helix and then monofunctionally photoreaction with DNA bases. Their synthesis started from 5,7‐dihydroxy‐4‐methylcoumarin, which was condensed with α‐halo‐ketones; the resulting ketoethers were then cyclized to give the title compounds.