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p. 520-526
Received: 2 March 2004 / Accepted: 15 March 2004 / Published: 30 June 2004
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| Download PDF Full-text (170 KB) Abstract: The reactions of 2-chloropyrimidine with methylamine, ethylamine and piperidine gave the corresponding 2-N-methylamino-, 2-N-ethylamino- and 2N- piperidinopyrimidines, respectively. The fluorescence properties of these alkylamino derivatives in chloroform, ethyl acetate, carbon tetrachloride, acetone, ether, ethanol and methanol were studied. All the alkylamino derivatives showed the highest fluorescence intensity in polar protic solvents; thus 2-N-methylaminopyrimidine (highest fluorescence intensity at 377 nm when excited at 282 nm) and 2-N-ethylaminopyrimidine (highest fluorescence intensity at 375 nm, when excited at 286 nm) showed the highest fluorescence in methanol. In ethanol, 2-N-piperidinopyrimidine showed a fluorescence peak at 403 nm when excited at 360 nm and in chloroform it fluoresced at 392 nm when excited at 356 nm.
p. 527-534
Received: 26 February 2004 / Accepted: 5 April 2004 / Published: 30 June 2004
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| Download PDF Full-text (183 KB) Abstract: The 1,3-dipolar cycloaddition of nitrile oxides to 1-cyanoenamines gives 5-aminoisoxazoles regioselectively. Moderate to good yields could be obtained depending on the method used to generate the nitrile oxides. The intermediate isoxazolines could not be isolated.
p. 535-540
Received: 11 December 2003; in revised form: 15 September 2004 / Accepted: 19 September 2004 / Published: 30 June 2004
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| Download PDF Full-text (171 KB) Abstract: Substituted imidazolinones containing heterocyclic carboxylic acids as substituents and possessing herbicidal properties were synthesized by cyclization of 2-amino-2,3-dimethylbutyramide with heterocyclic ethyl dicarboxylates under mild conditions. The use of NaH as base leads to a significant increase in the reaction rate and allows the preparation of the target compounds in high yields.
p. 541-549
Received: 26 December 2003; in revised form: 24 March 2004 / Accepted: 3 April 2004 / Published: 30 June 2004
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| Download PDF Full-text (186 KB) Abstract: Allylic alcohols were isomerized into ketones by the action of the Grubbs reagent. Some model alcohols were prepared and tested under similar conditions to reveal that less substituted alkenes rearrange more easily. More hindered alcohols are stable under these conditions, however, the simple allylic alcohols tend to isomerize producing ethyl ketone and the corresponding degraded methyl ketone.
p. 550-567
Received: 26 November 2003; in revised form: 15 March 2004 / Accepted: 16 March 2004 / Published: 30 June 2004
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| Download PDF Full-text (248 KB) Abstract: Complexes of phosphated cornstarch and waxy cornstarch with casein were prepared and characterised. They were prepared from casein in defatted milk and corn and waxy corn starches phosphated to degree of substitution values (DS) of 0.0637 and 0.0968, respectively. The components were blended in starch to casein ratios of 2:1, 1:1, and 1:2, then precipitated with hydrochloric acid. Aqueous solubility, water binding capacity, IR spectra, and thermal analysis (thermogravimetry, TG, and differential thermogravimetry, DTG) of the precipitates revealed that they were not simple physical mixtures of the components. The components interact with one another electrostatically with involvement of the starch phosphate groups and the peptide bonds of casein as documented by the IR spectra. Because of their insolubility in 7 M aqueous urea solution they might also be considered as complexes in which the components were chemically bound. Enzymatic studies showed that they are biodegradable materials.
p. 568-573
Received: 3 June 2003; in revised form: 22 December 2003 / Accepted: 15 February 2004 / Published: 30 June 2004
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| Download PDF Full-text (152 KB) Abstract: The known flavonoid chrysin-7-O-(β-D-glycopyranoside) (chrysin glucoside,1) as a major fraction and a new glycoside flavone, chrysin-7-O-β-D-[(6”-acetyl)glycopyranoside] (2) were isolated from the flowers and leaves of CalycotomeVillosa Subsp. Intermedia, They were identified by UV-Vis, 1R, 1 H-, 13 C-NMR and ESI-MS.
p. 574-582
Received: 8 March 2004 / Accepted: 7 April 2004 / Published: 30 June 2004
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| Download PDF Full-text (180 KB) Abstract: Some aryl-2-methyl-1-pyrrolo[1,2-a]pyrazinones were designed and prepared to study the Structure-Activity Relationships (SAR) of pyrrolo[1,2-a]pyrazinone derivatives. With methyl pyrrole-2-carboxylate as the starting material, the title compounds were prepared through N-alkylation and two novel cyclizations. Eleven aryl-2-methyl-1- pyrrolo[1,2-a]pyrazinone derivatives not previously reported in the literature are presented in this paper. Some of them show potent anti-inflammatory and analgesic activities.
p. 583-594
Received: 30 October 2003; in revised form: 17 May 2004 / Accepted: 25 May 2004 / Published: 30 June 2004
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| Download PDF Full-text (189 KB) Abstract: Preparation of magnesium, lanthanum, and bismuth(III) complexes of 3.6 kDa maltodextrin and some properties of the resulting materials are presented. The metal derivatives contain metals bound to the oxygen atoms of the hydroxyl groups of maltodextrin. Additionally, the metal atoms are coordinated to the hydroxyl groups of the D-glucose units of the macroligand. Such coordination stabilized the metal – oxygen bond against hydrolysis, even in boiling water. The presence of magnesium and lanthanum atoms increased the thermal stability of maltodextrin, whereas bismuth atoms decreased it.
p. 595-601
Received: 23 April 2004 / Accepted: 8 May 2004 / Published: 30 June 2004
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| Download PDF Full-text (153 KB) Abstract: After comparing our previous and newer results for numerous oxidativearomatic iodination experiments using various brands of active MnO2 as the oxidants,we recommend the use of a Chemical Manganese Dioxide (Aldrich CMD; 90 %MnO2 ) as the oxidant of choice, since it is satisfactorily pure and chemically active, andis notably less costly than other options.
p. 602-608
Received: 22 March 2004 / Accepted: 2 May 2004 / Published: 30 June 2004
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| Download PDF Full-text (176 KB) Abstract: A flavanone and a flavanone glycoside, together with vomifoliol, have been isolated for the first time from the aerial parts of the plant Echiochilon fruticosum and identified. Their structures were established on the basis of spectroscopic measurements, mainly 2D NMR using COSY, HMQC and HMBC experiments.
p. 609-616
Received: 25 March 2004 / Accepted: 26 April 2004 / Published: 30 June 2004
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| Download PDF Full-text (160 KB) Abstract: Quinazolinone and quinazolinedione derivatives are of considerable interest due to their wide array of pharmacological properties. In this paper we report the synthesis of ten quinazolinediones. The previous isolation of two of these compounds, namely 1-methyl-3-(2'-phenylethyl)-1H,3H-quinazoline-2,4-dione and 1-methyl-3-[2'-(4'- methoxyphenyl)ethyl]-lH,3H-quinazoline-2,4-dione, from the seed husks of Mexican Zanthoxylum species has been reported
p. 617-621
Received: 23 April 2004 / Accepted: 8 May 2004 / Published: 30 June 2004
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| Download PDF Full-text (174 KB) Abstract: A fast and simple method for the oxidative iodination of some aromatic amines, either under microwave irradiation or conventional heating, is reported, using diiodine and ortho-periodic acid as the oxidant. The reactions were carried out in boiling CH2Cl2 solutions under a reflux condenser. For the microwave assisted reactions, the reaction times were always notably shortened, but the yields were usually less influenced as compared with the conventional method.
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