-
[show abstract]
[hide abstract]
ABSTRACT: Copper(I)-catalyzed alkyne-azide 1,3-cycloaddition reaction (CuAAC, Sharpless-Meldal reaction) of various α-azido ketones such as substituted 2-azidoacetophenones, 2-azidobenzosuberone and 3-azido(thio)chromanones with terminal alkynes was studied. The reaction resulted in the formation of the expected 1,2,3-triazoles in moderate to good yields although the reactivity was somewhat lower than in the case of simple azides. Reaction of ethynylchromones as alkynes gave interesting dichromonoid systems bridged by a triazole unit.
Molecular Diversity 02/2012; 16(1):91-102. · 3.15 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Organic azides are known and utilized in the synthetic organic chemistry as amine precursors, potential sources of nitrenes, dipoles useful in 1,3-dipolar cycloadditions and starting materials of phosphoranes for a long time, and their literature has been overviewed by several authors. On the other hand, there are some special subclasses within the azides which possess peculiar and interesting properties differing from those of the majority and offering extra synthetic possibilities. In this critical review we wish to give an exhaustive overview on the synthesis and synthetic potential of α-azido ketones and related systems, an underestimated group of compounds. The enhanced acidity of the α-hydrogen offers various new synthetic applications including the creation of a new C-C bond, while the joint presence of the carbonyl and vinyl functions of α-azido-α,β-unsaturated ketones results in a special reactivity, too. Chemo- and stereoselectivity issues also represent important points which are discussed in detail. Finally, the usefulness of the titled derivatives in the synthesis of various heterocycles is reviewed (273 references).
Chemical Society Reviews 02/2011; 40(5):2797-847. · 28.76 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Effective enantiomeric separations of erythro- and threo-8.O.4'-neolignans with different aromatic substitution pattern (1a-i, 2a-i) are achieved on the commercially available chiral stationary phase cellulose tris(3,5-dimethylphenylcarbamate) (Chiralcel OD). It is shown that the chiral recognition of the stationary phase is significantly dependent on the substitution pattern of the racemic compounds. Online liquid chromatography (LC)-circular dichroism (CD) analysis allows for the establishment of a correlation between the absolute configuration of the separated erythro-8.O.4'-neolignans and their characteristic CD transitions, which could be used to determine or revise the configuration of previously isolated erythro-8.O.4'-neolignans. Although the absolute configurations of threo-isomers is not determined unambiguously from the LC-CD analysis, it is proven that both their elution order and chiroptical properties are significantly influenced by the substitution pattern of the aromatic rings.
Journal of chromatographic science 11/2004; 42(9):478-83. · 0.88 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The structure of the antifungal metabolite coniothyriomycin was systematically modified by changing the acids of the open chain imide, modification of the hydrophobicity, variation in the degree of saturation, replacement of carbons by nitrogen or oxygen, and incorporation of the open chain molecule into cyclic arrangements. Structure-activity studies showed that antifungal activity was retained by replacement of phenylacetic acids by benzoic acids in the imide structure but diminished by hydrogenation of the fumaric ester part.
The Journal of Antibiotics 04/2003; 56(3):296-305. · 1.65 Impact Factor
