Chromenopyridines: promising scaffolds for medicinal and biological chemistry.

Chromenopyridines constitute a structurally diverse class of compounds with a wide range of bioactivities and increasing presence in drugs. Here we analyze the scope of the synthetic methodology to access this nucleus with emphasis on multicomponent reactions and robust methodologies. Reactivity issues, medicinal applications and other properties are also reviewed.

Introduction of heteroatom-based substituents into 1,4-dihydropyridines by means of a halogen-mediated, oxidative protocol: diamination, sulfonylation, sulfinylation, bis-sulfanylation, and halo-phosphonylation processes

The natural tendency of 1,4-dihydropyridines to undergo "biomimetic" oxidation to afford pyridinium salts can be switched off and, through the use of reagents that interact electrophilically with the enamine moiety present in the heterocyclic system, it is possible to promote alternative oxidations. In this way, efficient regio- and stereocontrolled synthetic methods have been developed that lead to diversely substituted di- and tetrahydropyridines. These include iodoazidation, diamination, bis-sulfonamidation, sulfonylation, sulfinylation, thiocyanation, sulfanylation, bis-sulfanylation, and halo-phosphonylation processes.

Oxidative diphosphonylation of 1,4-dihydropyridines and pyridinium salts

An oxidative double phosphonylation of dihydropyridines 1 and pyridinium salts 2 is achieved through the use of dialkyl phosphites, DDQ, and triethylamine. Acceptable to good yields of 2, 6-diphosphonylated-1,2-dihydropyridines 3 are obtained in a one-pot reaction involving tandem nucleophilic addition/oxidation processes. Isomerization of 3 to the more stable 2,4-diphosphonylated-1, 4-dihydropyridine 4 was observed in some cases.

[Wunderlich's syndrome in a patient on hemodialysis with acquired cystic kidney disease. A report of a new case]. / Síndrome de Wunderlich en paciente en hemodiálisis con enfermedad quística renal adquirida. Aportación de un nuevo caso.

We report a new case of Wunderlich's syndrome (spontaneous perirenal hematoma) in a patient with chronic renal failure undergoing hemodialysis secondary to acquired renal cystic disease. The literature relative to this condition is review.

Molecular emission spectra in the soft X-ray region.

Spectra from several chlorine-containing hydrocarbon molecules excited to x-ray fluorescence have been recorded by a double crystal spectrometer with high resolving power. This study focuses on the region near the occurrence of the transition Kbeta(1,3) (1s(-1)-->3p(-1)) in chlorine. Whereas the free atom spectrum (from a single vacancy process) consists of an unresolved spin-orbit doublet, e.g., in argon, the molecular spectra often contain several lines. In free atom spectra and in molecular spectra also, there are extra lines or unresolved multiplets (satellites) due to multiple vacancy processes. In this report, these satellite lines are experimentally sorted out of the spectra and the remaining emission peaks associated with possible final state configuration containing a vacancy, i.e., the electronic terms of the molecule.

Optical constants of germanium.

The authors have attempted to assess the disagreement of various investigators on the optical properties of germanium in the far uv. The analyis subjected the reported data, out to about 25 eV, to the following tests: (1) an internal consistency check when possible by applying the Kronig-Kramers dispersion relations to the optical constants; (2) an evaluation of the optical oscillator strength distribution for the spectrum under study; (3) correlation of the values of Im(l/*) from the optical data with the characteristic electron energy loss spectrum for the material; and (4) evaluation of the oscillator strength sum for the electron energy loss distribution. A set of optical constants derived from the characteristic electron energy loss data is presented and discussed. Also, an estimate of the source of errors incurred in the application of the Kronig-Kramers dispersion relations are given and discussed in terms of optical data.