Atropoisomerismo: o efeito da quiralidade axial em substâncias bioativas

Atropisomerism is a special kind of stereoisomeric relationship that arises from the freezing of a certain conformation of an organic molecule, associated with a high rotational barrier about a single covalent bond. Atropisomerism has been originally described in orto-functionalyzed biphenyl derivatives, but a lot of other organic functionalities can present this structural phenomenon, characterized by the presence of chiral properties in compounds that don't present classical stereogenic centers. Atropisomeric compounds, intermediates and catalysts have well-know importance in organic synthesis, but the influence of the axial chirality in substances able to modulate biological systems is still not very exploited in drug design and development. In this context, the present account describes the importance of this structural property in the medicinal chemistry of different classes of bioactive compounds or therapeutic agents, emphasizing how atropisomerism could affect the molecular recognition of a ligand or a prototype by the target bioreceptor.

A internet como fonte de informação bibliográfica em química

The internet is an important tool for obtaining information. It offers vast amounts of information ranging from basic to advanced, from general to specific. Nevertheless, its quality cannot be classified or graded. Furthermore, some technical and/or specific information may not be available for free. This work primarily shows the great utility of the internet for getting suitable information in Chemistry and emphasizes open access and quality sites in Chemistry. It directs the reader towards many useful sites within some branches of Chemistry that provide powerful tools of research and study that may not be obtained easily at a library.

Metátese de olefinas aplicada ao fechamento de anéis: uma ferramenta poderosa para a síntese de macrociclos naturais

For a quarter of a century, metathesis has become indispensable for the synthesis of natural and non-natural products, particularly of biologically active compounds. This review illustrates through a maximum of appropriate examples the power and the versatility of the metathesis ring-closure (RCM) reaction as a key ring-closure methodology for the synthesis of natural macrocycles. Its high functional group compatibility as well as the possibility of further transformations makes this reaction a powerful tool in the cases where the structural framework and function requirements are difficult to meet.

La Moscovie.

[N. 1:12000000].

Neuvostoliittolaisia puna-armeijan ruotsin-, saksan- ja vironkielisiä julisteita sekä suurikokoisia lentolehtisiä 001

Sotilas kantaa selässään toista sotilasta, jolla saksalaismallinen kypärä ja hihanauhassa hakaristi; ja joka uhkaa kantajaansa pistoolilla. Kuvateksti: "Soldater och officerar finska arme! Sluta utcjuta blod för Hitlers intresse! Kasta bort fascister i fran sitt land!"

Jan Harmsen, den fattige fader och moderlöse gossen ifrån Holland: en märkwärdig berättelse

Nimiösivulla myös: Öfwersättning.

A questão russa: seu lugar nas reflexões de Vanguarda Socialista

Vanguarda Socialista, jornal editado por Mário Pedrosa no Rio de Janeiro, de 1945 a 1948, elabora uma proposta política socialista e democrática como alternativa à concepção bolchevique, que acredita superada pela história. Nessa medida, a "questão russa" encontra-se no centro das preocupações do grupo. Este artigo procura não só analisar a explicação do jornal para as origens da burocracia na URSS, mostrando as contradições que a perpassam, como também estabelecer a filiação do grupo às idéias de Rosa Luxemburgo, na tentativa de esclarecer as referidas contradições.

Stendhal pensador: o conceito feito narrativa

Trata-se aqui de esboçar aspectos do pensamento - em seu sentido conceitual e sistemático - de Stendhal, seu discurso reflexivo, manifesto no estilo narrativo através do romance, sobretudo em Le Rouge et le Noir.

La Recherche des disparus : organe de l'Association française pour la recherche des disparus

1915/09/12 (N26)-1915/09/19.

La Recherche des disparus : organe de l'Association française pour la recherche des disparus

1915/03/14 (N4).

La Recherche des disparus : organe de l'Association française pour la recherche des disparus

1916/03/26 (N40)-1916/04/02.

La Recherche des disparus : organe de l'Association française pour la recherche des disparus

1917/01/28 (N62)-1917/02/04.

La Recherche des disparus : organe de l'Association française pour la recherche des disparus

1916/05/21 (N44)-1916/05/28.

La Recherche des disparus : organe de l'Association française pour la recherche des disparus

Variante(s) de titre : La Recherche des disparus : organe officiel de l'Association française pour la recherche des disparus et de l'Agence des prisonniers de guerre de la Croix-rouge française