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p. 731-738
Received: 21 July 2006 / Accepted: 27 September 2006 / Published: 2 October 2006
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| Download PDF Full-text (83 KB) Abstract: The catalytic ability of ZrO2 /SO4 2- to promote solventless three-componentcondensation reactions of a diversity of aromatic aldehydes, urea or thoiurea and ethylacetoacetate was studied. Products resulting from Hantzsch and/or Biginelli multi-component reactions are obtained in the presence of solid acid catalysts using the samereactants but different temperature conditions. The sulfated zirconia catalyst can berecovered and recycled in subsequent reactions with a gradual decrease of activity.
p. 739-750
Received: 9 August 2006; in revised form: 24 August 2006 / Accepted: 24 August 2006 / Published: 2 October 2006
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| Download PDF Full-text (96 KB) | Abstract: 2-Thiohydantoin derivatives are produced by heating a mixture of thiourea and an α-amino acid. The method described offers the advantages of simplicity, low cost, easy work-up and scalability.
p. 751-757
Received: 27 September 2006; in revised form: 10 October 2006 / Accepted: 10 October 2006 / Published: 12 October 2006
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| Download PDF Full-text (48 KB) Abstract: A convenient synthesis of 3,11-dimethylnonacosan-2-one (1) is described. Our strategy involves the use of well known C–alkylation and ethyl acetoacetate synthesis reactions as key steps. We expect that this method will prove to be useful for large scale preparation of 1 and modification of dimethylnonacosanones.
p. 758-767
Received: 2 September 2006; in revised form: 10 October 2006 / Accepted: 16 October 2006 / Published: 18 October 2006
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| Download PDF Full-text (200 KB) Abstract: The synthesis of the alkamides 2Z,4E-undeca-2,4-dien-8,10-diynoic acid isobutyl amide (1) and 2Z,4E-undeca-2,4-dien-8,10-diynoic acid isobutyl amide (5) was accomplished by organometallic coupling followed by introduction of the doubly unsaturated amide moiety. The distribution of these two amides in accessions of the nine species of Echinacea was determined.
p. 768-775
Received: 28 September 2006; in revised form: 11 October 2006 / Accepted: 12 October 2006 / Published: 19 October 2006
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| Download PDF Full-text (120 KB) Abstract: The acid-catalyzed cyclocondensation in refluxing acetonitrile of aqueousglyoxal with N-heteroaryl-N'-phenylureas 4a-f (heteroaryl = 2-thiazolyl, 2-pyrimidinyl,2-pyrazinyl, 2-pyridinyl, 3-pyridinyl and 2-benzimidazolyl) led to the formation of thecorresponding 1-heteroaryl-3-phenyl-4,5-dihydroxy-2-imidazolidinones 5a-f. All theproducts were characterized by elemental and spectroscopic analyses. The free-energybarrier (∆GP≠ for prototropic tautomerism in 1-(2-benzimidazolyl)-3-phenyl-4,5-dihydroxy-2-imidazolidinone (5f) was determined by dynamic NMR studies to be 81 ± 2KJ molP-1
p. 776-785
Received: 26 July 2006; in revised form: 17 September 2006 / Accepted: 10 September 2006 / Published: 21 October 2006
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| Download PDF Full-text (88 KB) Abstract: We report the synthesis and properties of eight new tetrathiafulvalene (TTF) derivatives containing two different functionalities, prepared with the aim of obtaining stable organic materials. The four acetoxyphenyl- and four hydroxyphenyl TTFs were synthesized via Wittig-type condensations. The electrochemical properties of these redox-active molecules were studied by cyclic voltammetry. Charge transfer complexes with tetracyanoquinodimethane (TCNQ) were prepared by chemical redox reactions. The complexes have been proven to give conducting materials. The UV-VIS and IR spectra of the TCNQ salts were recorded and used to characterize and estimate the degree of charge transfer of these complexes.
p. 786-791
Received: 13 September 2006; in revised form: 16 October 2006 / Accepted: 16 October 2006 / Published: 20 October 2006
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| Download PDF Full-text (74 KB) Abstract: A new prenylated flavon-4-ol with a modified ring A, which we have named pongaflavanol (1), was isolated from the stem bark of Pongamia pinnata along with the known compound tunicatachalcone (2). The structure of compound 1 was elucidated on the basis of spectroscopic data.
p. 792-807
Received: 29 September 2006; in revised form: 18 October 2006 / Accepted: 23 October 2006 / Published: 24 October 2006
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| Download PDF Full-text (160 KB) Abstract: For the first time ent-labdanes have been synthetised starting from ent-halimic acid, following a route that is the reverse of the biosynthetic one leading to the former compounds.
p. 808-816
Received: 13 September 2006; in revised form: 12 October 2006 / Accepted: 23 October 2006 / Published: 25 October 2006
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| Download PDF Full-text (56 KB) Abstract: Chemical analysis of the secondary metabolite pattern of the sacoglossan mollusc Elysia cf. expansa, collected along South Indian coasts, showed the presence of the typical Caulerpa-derived sesquiterpene caulerpenyne (1) and two new minor co- occurring metabolites, the compounds dihydrocaulerpenyne (4) and expansinol (5). The chemical characterization of these molecules, structurally related to 1, is reported
p. 817-826
Received: 29 August 2006; in revised form: 12 October 2006 / Accepted: 16 October 2006 / Published: 25 October 2006
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| Download PDF Full-text (171 KB) Abstract: Roots of Vetiveria zizanioides Nash (Mae Hae; Thai ecotype) planted in three different cultivation systems (normal soil, normal soil with added microbes and semi- hydroponically) were extracted using a simultaneous steam distillation and solvent extraction (SDE) apparatus. Yields of the essential oils obtained were 0.27, 0.18 and 0.06%, respectively. The separation profiles obtained by comprehensive two-dimensional gas chromatography (GC×GC) and solid phase microextraction (SPME)-GC×GC analyses of the crude essential oils showed a total of 156 and 48 well-resolved components, respectively. The highly volatile fractions isolated from the three essential oils by SPME were subjected to analysis by GC-MS and 42 compounds were identified in total. Volatile component profiles of the oils obtained by normal soil and semi-hydroponic cultivation were similar, whereas a quantitative difference was noted in some major volatiles when the cultivation system containing microbes was utilized.
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