RESUMO
Silver acetylides and organic azides react under copper(I) catalysis to afford 1,4-disubstituted 1,2,3-triazoles. Mechanistic studies implicate a process involving transmetallation to copper acetylides prior to cycloaddition. This work demonstrates that silver acetylides serve as suitable precursors for entry into copper-mediated coupling reactions. This methodology allows the incorporation of volatile and difficult-to-handle acetylenes into the triazole core.
Assuntos
Alcinos/química , Azidas/química , Cobre/química , Prata/química , Triazóis/síntese química , Catálise , Ciclização , Triazóis/químicaRESUMO
A library of spirooxindoles containing varied elements of structural and stereochemical diversity has been constructed via a three step, one pot nitrile hydrozirconation-acylation-cyclization reaction sequence from common acyclic indole intermediates. The resulting library was evaluated for novelty through comparison with MLSMR and Maybridge compound collections.
Assuntos
Indóis/síntese química , Compostos de Espiro/síntese química , Zircônio/química , Acilação , Técnicas de Química Combinatória , Ciclização , Indóis/química , Nitrilas/química , Compostos de Espiro/químicaRESUMO
Glycosyl fluorides can be synthesized from thio-, seleno-, and telluroglycosides and glycosyl sulfoxides using the aminodifluorosulfinium tetrafluoroborate reagents Xtalfluor-E and -M, with or without added N-bromosuccinimide. Mechanistic studies provide evidence that fluoride is delivered from the tetrafluoroborate counterion.
Assuntos
Glicosídeos/síntese química , Halogenação , Hidrocarbonetos Fluorados/síntese química , Dicloretos de Etileno/química , Hidrocarbonetos Fluorados/química , Compostos Organometálicos/química , Compostos Organosselênicos/química , Solventes/química , Sulfóxidos/química , Compostos de Enxofre/química , Telúrio/química , Tioglicosídeos/químicaRESUMO
We report the widespread occurrence of structurally diverse oleuropeyl glucose esters, including the new diester eucaglobulin B, localized specifically to the essential oil secretory cavities of myrtaceous species. Clear taxonomic patterns in the composition of cavity extracts within the genus Eucalyptus are shown with species from subgenus Symphyomyrtus dominated by oleuropeyl glucose esters and species from subgenus Eucalyptus dominated instead by the flavanone, pinocembrin. We also examined the intra-species occurrence of oleuropeyl glucose esters by quantifying the abundant constituents cuniloside B and froggattiside A in trees from two populations of Eucalyptus polybractea R.T. Baker. All trees contained both compounds, which were positively correlated with total essential oil concentration. This apparent ubiquity of oleuropeyl glucose esters at both intra- and inter-specific levels in Eucalyptus is indicative of important physiological or ecological functions. The significance of their prevalence and the sequestration of these esters and also pinocembrin to the extracellular domain of secretory cavities is discussed in light of their potential biological activities and our findings that they are spatially segregated to the exterior of cavity lumina. The localization of oleuropeyl glucose esters to a specific and isolatable tissue type has the potential to aid in future elucidation of function and biosynthesis.