83 research outputs found
Facile Diastereoselective Entry to 4 beta-Acylamidation of Neu5Ac2en Glycals Using Their N-Perfluoroacylated Congeners as Key Tools
No full textAn efficient protocol for the 4 beta-acylamidation of the N-acylated glycals of Neu5Ac by using the corresponding N-perfluoroacylated congeners as key tools has been developed and applied to the synthesis of glycals combining the features of the molecules with antiviral properties
A Simple Synthetic Access to Differently 4-Substituted Neu5Ac2en Glycals Combining Elements of Molecules with Anti-Neuraminidase Activity
No full textA protocol for direct access to C-4-functionalized Neu5Ac2en derivatives by allylic substitution of an α-acetoxy group with various nucleophiles is reported. The DANA acetamido group is exchanged for a trifluoroacetylamido group (as in FANA) to avoid the formation of a stable 4,5-oxazoline. With thiols, the reaction involves an initial attack at the anomeric carbon (Ferrier reaction) under kinetic control, followed by an equilibration of the nucleophile to the thermodynamically
more stable 4-position
Simple and Rapid Procedures for the Synthesis of 5-Acylated 4 beta-Acylamido- and 4 beta-Acetoxyneuraminic Acid Glycals
No full textTwo simple and rapid procedures affording 4 beta-acylamido- and 4 beta-acetoxyneuraminic acid glycals acylated or perfluoroacylated at the 5-amino group are reported. The first protocol avoids the formation of oxazolines to synthesize the 4 beta-acetamido glycals through the Ritter reaction. The second passes through the oxazoline derivative to prepare 4 beta-acetoxyneuraminic acid glycals. Both protocols start from peracetylated methyl neuraminate, acylated at the amino group with a normal, a glycolyl, or a perfluoroacyl group, or with the corresponding peracetylated glycal methyl esters (of the DANA or FANA series)
SYNTHESIS AND BIOLOGICAL EVALUATION OF SOME UNSATURATED SIALIC ACID ANALOGUES AS POTENTIAL SIALIDASE INHIBITORS
No full textThis work represents a part of a larger research project directed to study the correlation between the different structures of unsaturated Neu5Ac derivatives and their inhibitory activity against viral, bacterial and mammalian sialidases. So, interested in finding the general features to define a potent and selective inhibitor of a particular kind of sialidase, we have set up many rapid, simple and efficient protocols to introduce new substituents into the DANA structure. In this thesis we accomplish:
- the synthesis of new C-4α aminated DANA derivatives;
- the first synthesis of N-perfluorinated C-4 epimers of DANA, clarifying also their mechanism formation and the key role of the oxazoline derivative;
- the first Ritter-like reaction performed on Neu5Ac derivatives, to obtain new 4β-N-acetylated Neu5Ac2en derivatives;
- The extension of the Ritter reaction leading to formulate a general nucleophilic substitution at C-4 position of e Neu5Ac glycals, synthesizing a great number of compounds by the rapid introduction of alcohols, thiols, sulfonamides and alogens;
-The set up of a general method to introduce nucleophiles at C-2 position of Neu5Ac analogues to obtain new 3,4 unsaturated alkylglycosides, to be biologically tested, or to be used as synthetic intermediate to functionalize C-3 and C-4 positions of neuraminic acid derivatives;
- The preliminary fluorimetric sialidase inhibition assays of part of the obtained compounds, against Vibrio cholerae, Newcastle disease virus, Clostridium perfringens and mammalian Neu3 sialidases. We obtain interesting results especially regarding the NDV neuraminidase inhibition data, suggesting the possibility to design a selective NDV NA inhibitor by tuning the substituent at C-5 position
Las aves del sitio arqueológico "El Shincal de Quimivil", Provincia de Catamarca, Argentina
No full textEl registro de aves recolectadas en yacimientos arqueológicos del Noroeste de Argentina ha sidoescasamente abordado en los análisis arqueofaunísticos. En el presente trabajo se analiza y describela avifauna colectada en el sitio arqueológico El Shincal de Quimivil, una importante instalaciónadministrativa Inka ubicada en la provincia de Catamarca, Argentina. Entre los materiales registradosse indica la presencia de Pterocnemia pennata, Eudromia cf. E. elegans, Nothura sp., Platalea ajaja, cf.Buteo sp., Aratinga sp., Columbina sp., Zonotrichia capensis, y Saltator sp. Los taxones P. pennata, Eudromiay Nothura fueron introducidos al sitio con una finalidad de consumo antrópico. La presencia de cf.Buteo, Psittacidae, Platalea, y posiblemente Columbina se relacionaría a contextos ceremoniales, talcomo fuera indicado para otros sitios arqueológicos de Sudamérica. Zonotrichia y Saltator habrían sidoincluidos en la muestra de manera natural. Este conjunto constituye la avifauna taxonómicamentemás diversa recolectada en algún sitio arqueológico del Noroeste Argentino.Registration of birds collected in archaeological sites in the Northwest region in Argentina is a scarcely analyzed matter in zooarchaeological works. In this paper we analyzed and described the birds collected at the archaeological site El Shincal of Quimivil, Catamarca Province, Argentina. The site has been an important Inka administrative post. Among the materials recorded indicated the presence of Pterocnemia pennata, Eudromia cf. E. elegans, Nothura sp., Roseate Spoonbill, cf. Buteo sp., Aratinga sp., Columbina sp., Zonotrichia capensis, and Saltator sp. P. Pennata, and Nothura Eudromia were introduced to the site by anthropic agents with a consumer purpose. The presence of cf. Buteo, Psittacidae, Roseate, and possibly Columbina is related to ceremonial contexts, as was indicated for other archaeological sites in South America. Saltator and Zonotrichia have been included in the sample naturally. This set is the taxonomically more diverse assemblage of archaeological avifauna collected somewhere in Northwest Argentina.Fil: Agnolin, Agustin Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; ArgentinaFil: Agnolin, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
The fossil record of the Bramble-shark Echinorhinus (Echinorhiniformes, Echinorhinidae) in South America
No full textThe present contribution aims is to analyze the fossil record of the genus Echinorhinus in South America, and particularly Argentina. We made a first-hand examination of the species Echinorhinus pozzi from the early Miocene of Patagonia, and recognize it as a valid taxon. The species was originally described in the XIX century, and since then no author described or illustrated the original material based on observations of the actual specimens. The genus Echinorhinus is reported for the first time in late Miocene Paraná beds, based on the occurrence of fossil dermal spines. The species Echinorhinus maremagnum occurring in the latest Cretaceous outcrops from Patagonia in Chile and Argentina is considered valid and clearly distinguishable from E. lapaoi, contradicting recent claims that argue their synonymy.Fil: Bogan, Sergio. Universidad Maimónides; Argentina. Fundación de Historia Natural Félix de Azara; ArgentinaFil: Agnolin, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin
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