RESUMO
The role and importance of the identification of natural products are discussed in the perspective of the study of secondary metabolites. The rapid identification of already reported compounds, or structural dereplication, is recognized as a key element in natural product chemistry. The biological taxonomy of metabolite producing organisms, the knowledge of metabolite molecular structures, and the availability of metabolite spectroscopic signatures are considered as the three pillars of structural dereplication. The role and the construction of databases is illustrated by references to the KNApSAcK, UNPD, CSEARCH, and COCONUT databases, and by the importance of calculated taxonomic and spectroscopic data as substitutes for missing or lost original ones. Two NMR-based tools, the PNMRNP database that derives from UNPD, and KnapsackSearch, a database generator that provides taxonomically focused libraries of compounds, are proposed to the community of natural product chemists. The study of the alkaloids from Urceolina peruviana, a plant from the Andes used in traditional medicine for antibacterial and anticancer actions, has given the opportunity to test different approaches to dereplication, favoring the use of publicly available data sources.
Assuntos
Alcaloides/química , Amaryllidaceae/química , Produtos Biológicos/química , Química Computacional , Bases de Dados de Produtos Farmacêuticos , Estrutura Molecular , Raízes de Plantas/química , Metabolismo SecundárioRESUMO
The access to 1,2- and 1,1,2-substituted trans cyclopentanes via a sequential hydrozirconation/TMSOTf-mediated cyclization applied to 5-methoxypent-1-enes is presented. Involving a transient carbocation, the reaction was shown to be diastereo-convergent. Possibly performed in a nonracemic version, the reaction proved compatible with a range of functional groups affording a large panel of cyclopentanes.
RESUMO
The diastereoselective conjugate addition of secondary homoallylamines, obtained in the enantioenriched form via allylmetallation of imines, to α,ß-unsaturated esters is reported. This method allows access to valuable building blocks as well as heterocyclic skeletons, providing tertiary amines bearing two chains integrating a stereogenic center adjacent to the nitrogen atom.