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ABSTRACT: 2-Acetamido-2-deoxypentonolactones were synthesized from per-O-acetylated formazans of D-ribose, D- and L-arabinose, respectively. In dimethyl sulfoxide, a novel spontaneous transformation of the per-O-acetyl-pentose formazans into new 3,4,5-tri-O-acetyl-pent-2-enose formazans has been recognized. Additional examples for the occurrence of the isomerism between pseudo-aromatic chelate and open phenylazo-phenylhydrazone system were demonstrated by (1)H NMR spectroscopy in both the unprotected pentose formazans and 3,4,5-tri-O-acetyl-pent-2-enose formazans. Computational calculations supported higher stability of the ring form.
Carbohydrate research 04/2011; 346(12):1534-40. · 2.03 Impact Factor
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ABSTRACT: Data reported in this article describe the synthesis of Arg-rich oligopeptide conjugates of ferrocenecarboxylic acid on solid support with two different strategies and for the first time, the successful preparation of peptide conjugates of ferrocenylacrylic acid in solution. The antitumor effect of conjugates was analyzed by MTT assay in vitro. We demonstrated that ferrocenylacrylic acid possessing an enone (--CH==CH--CO--) moiety exhibited remarkable antiproliferative effect against human leukemia cells (HL-60) in vitro, but its effect was not improved by conjugation with hexa- or octaarginines. However, we observed highly increased water-solubility. In contrast, the results provide evidence that conjugation of ferrocenecarboxylic acid to Arg(n) (n = 6, 8) improved not only its water-solubility, but also antitumor effect on human leukemia cells in vitro.
Biopolymers 02/2007; 88(2):108-14. · 2.87 Impact Factor
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ABSTRACT: A series of novel 3(5)-aryl/ferrocenyl-5(3)-phenothiazinylpyrazoles and pyrazolines were obtained by substituent-dependent regioselective condensation of the corresponding (E)-3-(2-alkyl-10H-phenothiazin-3-yl)-1-aryl/ferrocenylprop-2-en-1-one with hydrazine or methylhydrazine in acetic acid. The different propensity of the primary formed beta-hydrazino adducts to undergo competitive retro-Mannich reaction was interpreted in terms of tautomerisation equilibrium constants calculated by DFT using a solvent model. The regioselectivity of the cyclisation reactions with methylhydrazine and the substituent-dependent redox properties of pyrazolines were also rationalized by comparative DFT calculations performed for simplified model molecules. On the effect of ultrasound-promoted oxidation with copper(II)nitrate phenothiazine-containing pyrazolines, enones and oxo-compounds were selectively transformed into sulfoxides. Only one sulfoxide enone was partially converted into an oxirane derivative. The structure of the novel products was determined by IR and NMR spectroscopy including COSY, HSQC, HMBC and DNOE measurements.
Organic & Biomolecular Chemistry 01/2007; 4(23):4375-86. · 3.70 Impact Factor
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ABSTRACT: Some new glycosides of 3-ferrocenyl-1-(4'-hydroxyphenyl)-prop-2-en-1-one were prepared and transformed into the corresponding pyrazoline and pyrazole derivatives. Using methyl-hydrazine, formation of regioisomers was observed. DDQ was found to be a mild and efficient reagent for the pyrazoline-pyrazole dehydroaromatization process. The structure of the new compounds was proved by IR and NMR spectroscopy. The in vitro antitumor activity of the substances was investigated against human leukemia (HL-60) cells by the MTT method. Among these new compounds some chalcone derivatives (3 a, 3 b, 5 a, and 5 b) showed attractive in vitro antitumor effects on human leukemia cells. These molecules contained ferrocenyl moieties and a p-hydroxy-phenolic ring or a size-independent apolar substitution of that.
ChemMedChem 11/2006; 1(10):1119-25. · 3.15 Impact Factor
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ABSTRACT: A new application of the formazyl activation provided selectively protected new derivatives of both 2-deoxy-D-galactose and 2-acetamido-2-deoxy-D-galactose formazans from 6-amino-6-deoxy-D-galactose 6,4-cyclic carbamate (1) under very simple conditions. The 1H NMR spectrum of the acetylated 2-deoxy derivative 7 revealed an equilibrium between chelated and unusual non-chelated forms of the formazan moiety in solution.
Journal of Carbohydrate Chemistry 08/2006; 20(7&8)(747–754 (2001)):747-754. · 0.63 Impact Factor
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ABSTRACT: New classes of sugar derivatives of the antibacterial drug norfloxacin (1) were synthesized by substituting the N‐4′ of the piperazinyl moiety of the molecule. Direct coupling with gluco‐ and galactopyranosyl units afforded glycosylamines 2–5. Introduction of urea or thiourea linkage between glycosyl and norfloxacin units was produced with the corresponding glycosyl isocyanates or isothiocyanates. For the synthesis of unprotected sugar urea compounds, a new approach was applied by using 1,2‐N, O‐carbonyl‐β‐D‐glycopyranoses. Hydrazinocarbonyl‐methyl‐ and ‐propyl spacers also were found appropriate for linking norfloxacin with sugar units.
Journal of Carbohydrate Chemistry 01/2005; 24(1):19-39. · 0.63 Impact Factor
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Journal of Organometallic Chemistry 694(26):4185-4195. · 2.38 Impact Factor
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ABSTRACT: A new approach towards simple aldonic acid derivatives starting from the corresponding aldoses via the 2-acetamido-2-deoxy formazans resulted in the synthesis of 2-acetamido-2-deoxy-d-galactono-1,4-lactone (8), and its 6-deoxy (11) and 6-azido-6-deoxy (14) analogues on treatment with trifluoroacetic acid. The five-membered ring structure of the lactones and that of the intermediate lactone phenylhydrazone (7) was proved by 1H and 13C NMR studies, including deuterium-induced differential isotope shift (DIS) measurements. With sodium borohydride, lactones 8 and 11 were converted into 2-acetamido-2-deoxy-d-galactitol (15) and its 6-deoxy analogue (17), respectively.
Carbohydrate Research.
