Chemical transformations of neolignans

Neolignans, generated by oxydative dimerization of propenylphenol and/or allylphenol, undergo further modifying steps. These biosynthetic reactions, confirmed in vitro, include Cope, retro-Claisen and Claisen rearrangements. Additionally acid catalysis effects convertions of bicyclo [3.2.1] octanoid neolignans into hydrobenzofuranoid neolignans, or inversely of hydrobenzofuranoid neolignans into bicyclo [3.2.1] octanoid neolignans, of hydrobenzofuranoid neolignans into futoenone type neolignans, of tetrahydrofuran neolignans into aryltetralin neolignans, as well as modifications by Friedel - Crafts reactions and the transformation of aryltetralin neolignans into arylindanones by pinacoline - pinacolone type rearrangement

Structural aspects of some hydrobenzofuran neolignans

The neolignans are defined as dimers of allylphenol and propenylphenol between itself or crossed, whose bond does not occur by the 8-8' carbons like lignans. This review centered on stereochemical aspects of the hydrobenzofuran type, a widespread skeleton among neolignans. The chemical structures established based on spectrometric data are registered in the literature. The absolute configurations reported previously were determined by chiroptical techniques. Some chemical transformations with neolignans, performed in previous studies, afforded products which are accumulated in other vegetal species and contributed to assign the unknown stereochemistry of these natural compounds. Possible biosynthetic pathways are also proposed

Biosynthesis of tetrahydrofuran lignans in Virola surinamensis

Através de experimentos de administração in vivo em plântulas de Virola surinamensis, observaram-se as incorporações de fenilalanina e do fenilpropanóide E-isoeugenol no 4-O-metil-5-metoxi-E-isoeugenol (E-isoelemicina) e na lignana tetraidrofurânica verrucosina.The labelled substrates phenylalanine and phenylpropanoid E-isoeugenol were incorporated to 5-methoxy-4-O-methyl-E-isoeugenol (E-isoelemicin) and to the tetrahydrofuran lignan verrucosin in plantlets of Virola surinamensis (Myristicaceae)

Determinación de la configuración relativa de las dehidro-mahuba lactonas, utilizando reactivos de desplazamiento

Los desplazamientos químicos inducidos por tres (1,1,2,2,3,3 —heptafluoro—7—7—dimetil—4, 6—octanodionato) de europio (III) Eu (fod) 3) 1, en el espectro de resonancia magnética nuclear protónica de las dihidro-mahuba lactonas 3 y 4 (diastereolsómeros), indican que el sitio preferencial de coordinación del lantánido es el oxigeno hidroxílico permitiendo, asi, establecer sus configuraciones relativas

Uptake of Seeds Secondary Metabolites by Virola surinamensis Seedlings

The major secondary metabolites and fatty acids occurring in the seeds of Virola surinamensis were monitored by GC-MS during germination and seedling development. The role as carbon source for seedling development was indicated considering that both classes of compounds were similarly consumed in the seeds and that no selective consumption of compounds could be detected

Aromatic compounds from three brazilian lauraceae species

Phytochemical investigations on three Brazilian Lauraceae species from, the Cerrado region of São Paulo State, Ocotea corymbosa (Meins) Mez., O. elegans Mez. and Persea pyrifolia Nees & Mart. ex Nees resulted in the isolation of flavonoids, an ester of the 4-O-E-caffeoylquinic acid, an aromatic sesquiterpene besides furofuran lignans. This is the first chemical study on the leaves of Ocotea elegans and O. corymbosa as well as the first report of non-volatile compounds from Persea pyrifolia