1,720,998 research outputs found
Methods for Carbon-Linked Glycosyl Amino Acid Synthesis. The Gateway to Artificial Glycopeptides
No full textA discussion on methods for Carbon-Linked Glycosyl Amino Acid Synthesis is reported
C-glycoside clustering on calix[4]arene, adamantane, and benzene scaffolds through 1,2,3-triazole linkers
No full textA route has been paved toward the preparation of triazole glycocluster libraries via the copper(I)-catalyzed modern version of the classical Huisgen 1,3-dipolar cycloaddition of azides to alkynes. Up to four 1,4-disubstituted 1,2,3-triazole rings bearing carbon-linked glycosyl fragments were constructed on various scaffolds via multiple cycloadditions of suitably polyfunctionalized calix[4]arene, adamantane, and benzene derivatives with ethynyl and azidomethyl C-glycosides. Each cycloaddition occurred with high regioselectivity to give exclusively the 1,4-disubstituted triazole ring in very high yield up to an average value of 98%. The high degree of efficiency of this approach and its wide scope constitute a simple and practical mean for the attachment of various sugar units to polyfunctionalized substrates
Synthesis of N-(tert-butoxycarbonyl)-N,O-isopropylidene serinal from serine methyl ester by a reduction-oxidation sequence
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Thiazole-based routes to amino hydroxy aldehydes, and their use for the synthesis of biologically active compounds
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Decoration of Dihydropyrimidine and Dihydropyridine Scaffolds with Sugars via Biginelli and Hantzsch Multicomponent Reactions: An Efficient Entry to a Collection of Artificial Nucleosides
No full textHere we present an overview of our work on the glycosylation of biologically relevant heterocycles. An array of stereochemically pure C-glycosylated dihydropyrimidine and dihydropyridine derivatives (artificial nucleosides) has been prepared. Our strategy involved the synthesis of suitably designed C-glycosylated reagents and their use as components in Biginelli and Hantzsch cyclocondensations. Molecular diversity has been explored within the collection on the basis of the nature and the number of sugar residues as well as their positions in the heterocyclic rings
Alkylation of camphor and pinanone imines of 2-(aminomethyl)thiazole. Enantioselective synthesis of 2-(1-amino alkyl)thiazoles
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Synthesis of C-glycosyl β-amino acids by asymmetric Mannich-type three-component reactions.
No full textC-Galactosyl and C-ribosyl b-amino acids were prepared by one-pot InCl3-catalyzed Mannich-type three-component
condensation (3CC) by combining the corresponding formyl C-glycoside, p-methoxybenzyl amine, and a ketene silyl acetal. In each case the reaction was highly stereoselective and afforded only one single product in good to excellent yields
Cycloaddition of N-arylketenimines to thiobenzophenones. Formation of 4H-3,1-benzothiazine and 2-iminothietan derivatives
No full textN-p-Tolyl and N-phenylketenimines (1) react with thiobenzophenones (2) by a formal 4 + 2 cycloaddition to give substituted 4H-3,1-benzothiazines (4) whose structures have been confirmed by an X-ray diffraction study, whereas the N-mesitylketenimine (5) leads to the 2-iminothietan (6) by a 2 + 2 cycloaddition
Model studies toward the Synthesis of Dihydropyrimidinyl and Pyridyl α-Amino Acids via Three-component Biginelli and Hantzsch Cyclocondensations.
No full textA novel and versatile strategy for the synthesis of heterocyclic R-amino acids has been described.
The use of components (aldehyde or â-ketoester) bearing a masked glycinyl moiety in Biginelli and
Hantzsch cyclocondensations allowed access to the 4-dihydropyrimidinyl-R-glycines, 4-dihydropyrimidinyl-
R-alanines, 4-pyridyl-R-alanines, and 2-pyridyl-R-alanines classes. Dihydropyrimidinylamino
acids were obtained as a mixture of diastereoisomers due to the formation of the stereocenter
at C4 of the dihydropyrimidinone ring. Individual stereoisomers were isolated as pure compounds
and their structures were assigned with the aid of X-ray crystallography and chiroptical properties.
The enantiomeric purity of a representative selection of the above amino acids was greater than
96% as verified by derivatization to the corresponding Mosher’s amides and subsequent 1H and
19F NMR spectroscopy. Incorporation of the 4-pyridyl-R-alanine derivative into a peptide chain is
also described
Three-Component Biginelli Cyclocondensation Reaction Using C-Glycosylated Substrates. Preparation of a Collection of Dihydropyrimidinone Glycoconjugates and the Synthesis of C-Glycosylated Monastrol Analogues.
No full textThe aldehyde-ketoester-urea cyclocondensation reaction has been revisited using C-glycosylated
reagents with the aim of exploring a potential entry to a library of dihydropyrimidinone
glycoconjugates. A collection of 13 mono- and bis-C-glycosylated dihydropyrimidinones has been
prepared by a parallel synthesis approach using the three-component promoter CuCl/AcOH/BF3â
Et2O. The sugar residues have been installed at either N1, C4, or C6 in the monoglycosylated
derivatives and at both the C4 and C6 in the bisglycosylated products. The mono- and bisglycosylated
products at C4 and C6 were obtained as mixtures of diastereoisomers with good to excellent
selectivities due to the asymmetric induction by the sugar residue in the formation of the C4
stereocenter of the dihydropyrimidinone ring. Individual stereoisomers were isolated as pure
compounds and their structures assigned with the aid of X-ray crystallography and chiroptical
properties. As a demonstration of this new concept in the Biginelli reaction, the synthesis of two
C4 epimer monastrol analogues bearing the ribofuranosyl moiety at C6 has been described
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