RESUMO
Juglanaloids A and B are recently isolated natural products characterized by an unprecedented spiro bicyclic isobenzofuranone-tetrahydrobenzazepinone framework and a promising antiamyloid activity. Here reported is a straightforward convergent total synthesis of these natural products, which were obtained in high enantiomeric purity (94% and >99% ee for juglanaloids A and B, respectively) through an eight-step longest linear sequence, based on an efficient and reliable enantioselective phase-transfer-catalyzed alkylation step. Considering the interesting biological activity of juglanaloids, this convenient, highly enantioselective, flexible, and predictable synthetic strategy promises to be a powerful tool for accessing potentially bioactive spiro bicyclic phthalide-tetrahydrobenzazepinone derivatives.
Assuntos
Alcaloides , Doença de Alzheimer , Compostos de Espiro , Estereoisomerismo , Doença de Alzheimer/tratamento farmacológico , Compostos de Espiro/química , Compostos de Espiro/síntese química , Compostos de Espiro/farmacologia , Alcaloides/química , Alcaloides/síntese química , Alcaloides/farmacologia , Estrutura Molecular , Benzofuranos/química , Benzofuranos/síntese química , Benzofuranos/farmacologiaRESUMO
The aerobic oxidation and oxidative esterification of 5-hydroxymethylfurfural (HMF) catalyzed by gold nanoparticles (AuNPs) supported on a semicrystalline nanoporous multiblock copolymer matrix consisting of syndiotactic poly(styrene)-cis-1,4-poly(butadiene) (sPSB) have been investigated. Depending on the reaction parameters (support nanoporosity, presence of water, solvent, temperature, cocatalyst, oxygen pressure), the conversion of HMF can be finely addressed to the formation of the desired oxidation product, such as 2,5-diformylfuran (DFF), 5-formylfuran-2-carboxylic acid (FFCA), methyl 5-(hydroxymethyl)furan-2-carboxylate (MHMFC), dimethyl furan-2,5-dicarboxylate (DMFC), and furan-2,5-dicarboxylic acid (FDCA), under optimized reaction conditions. The AuNP-sPSB catalyst is highly effective and selective because the polymer support acts as a conveyor and concentrator of the reactants toward the catalytic sites.
