617-55-0Relevant academic research and scientific papers
An approach to the chemotaxonomic differentiation of two European Dog's mercury species: Mercurialis annua L. and M. perennis L.
Lorenz, Peter,Duckstein, Sarina,Conrad, Juergen,Knoedler, Matthias,Meyer, Ulrich,Stintzing, Florian C.
experimental part, p. 282 - 297 (2012/05/04)
Mercurialis annua and M. perennis are medicinal plants used in complementary medicine. In the present work, analytical methods to allow a chemotaxonomic differentiation of M. annua and M. perennis by means of chemical marker compounds were established. In addition to previously published compounds, the exclusive presence of pyridine-3-carbonitrile and nicotinamide in CH2Cl2 extracts obtained from the herbal parts of M. annua was demonstrated by GC/MS. Notably, pyridine-3-carbonitrile was identified for the first time as a natural product. Further chromatographic separation of the CH2Cl2 extracts via polyamide yielded a MeOH fraction exhibiting a broad spectrum of side-chain saturated n-alkylresorcinols. While the n-alkylresorcinol pattern was similar for both plant species, some specific differences were observed for particular n-alkylresorcinol homologs. Finally, the investigation of H2O extracts by LC/MS/MS revealed the presence of depside constituents. Whereas, in M. perennis, a mixture of mercurialis acid (=(2R)-[(E)-caffeoyl]-2-oxoglutarate) and phaselic acid (=(E)-caffeoyl-2-malate) could be detected, in M. annua solely phaselic acid was found. By comparison with synthesized enantiomerically pure (2R)- and (2S)-phaselic acids, the configuration of the depside could be determined as (2S) in M. annua and as (2R) in M. perennis.
On the interactions of alkyl 2-hydroxycarboxylic acids with alkoxysilanes 2. Complexation and esterification of di- and tricarboxylic acids
Ansell, Richard J.,Meegan, Jonathan E.,Barrett, Simon A.,Warrinner, Stuart L.
scheme or table, p. 1460 - 1470 (2009/06/05)
The selective esterifications of l-malic, l-tartaric and citric acids with tetramethoxysilane Si(OMe)4, in methanol (MeOH) have been demonstrated for the first time. The interactions between these acids and Si(OMe)4, and also between
Enantiomerically pure tetrahydro-5-oxo-2-furancarboxylic esters from dialkyl 2-oxoglutarates
Drioli, Sara,Nitti, Patrizia,Pitacco, Giuliana,Tossut, Laura,Valentin, Ennio
, p. 2713 - 2728 (2007/10/03)
Enantiomerically pure tetrahydro-5-oxo-2-furancarboxylic esters can be prepared either by enzymatic resolution of the racemic γ-lactones themselves or by bioreduction with baker's yeast of dialkyl 2-oxoglutarates and subsequent cyclization of the resulting dialkyl 2-hydroxyglutarates. The best results were obtained by the former route, by which the desired compounds were isolated in high enantiomeric excess. Bioreductions were less satisfactory. In fact the hydroxyester intermediates were initially formed as racemic mixtures and their final enantiomeric enrichment was reached by asymmetric destruction, occurring in the bioreaction medium, however at the same time large amounts of alkyl 4-hydroxybutanoates were formed as side products.
Application of [Ru((R)-BINAP)(MeCN)(1-3:5,6-η-C8H11)](BF4) as a catalyst precursor for enantioselective hydrogenations
Daley, Christopher J.A.,Wiles, Jason A.,Bergens, Steven H.
, p. 1447 - 1456 (2007/10/03)
A catalyst system employing [Ru((R)-BINAP)(MeCN)(1-3:5,6-η- C8H11)](BF4) as catalyst precursor was evaluated using the enantioselective hydrogenations of tiglic acid, α-acetamidocinnamic acid, itaconic acid, methyl tiglate, dimethyl itaconate, geraniol, ethyl acetoacetate, and dimethyl oxaloacetate as a series of typical substrates. Acetone and MeOH were used as model aprotic and protic solvents, respectively. The hydrogenation of substrates containing an α,β-unsaturated carboxylic acid functionality required stoichiometric quantities of NEt3 to occur at reasonable rates in acetone solution, while in MeOH solution it did not. The enantioselectivities were typically higher in acetone than in MeOH. This catalyst system is among the more enantioselective ruthenium-BINAP type systems reported for the catalytic hydrogenation of substrates containing an α,β-unsaturated acid or ester functionality. The enantioselectivities for the hydrogenation of ketones ranged from poor (15%) to moderate (74%). 1,4- Dicarboxylate substrates with the prochiral olefin or ketone at the 2- position were all hydrogenated in good to high ee with the same enantioface selectivity both with our system and other catalysts reported in the literature. This raised the possibility that these substrates were hydrogenated through intermediates with similar structural features.
A Biocatalytic Approach to the Enantioselective Synthesis of (R)- and (S)-Malic Acid
Santaniello, Enzo,Ferraboschi, Patrizia,Grisenti, Paride,Aragozzini, Fabrizio,Maconi, Elisabetta
, p. 601 - 605 (2007/10/02)
(S)-Diethyl malate 1a was prepared (70-80percent yield; >98percent optical purity) by an enantioselective reduction of sodium diethyl oxalacetate 2 by fermenting baker's yeast (Saccharomyces cerevisiae).Other microorganisms were tested for their capability of reducing 2.Most of them afforded (S)-1a with ee from 8 to 94percent and only Candida utilis, Aspergillus niger and Lactobacillus fermentum ILC G18D preferentially reduced compound 2 to (R)-1a. (R)-Dimethyl malate 1b was obtained from (R,S)-malate 1b by hydrolysis with pig liver esterase (PLE), the highest ee (93percent) being realized at 0 deg C in 20percent aqueous methanol.Enzymatic hydrolyses of protected malates 1d and 1e did not lead to improvement of the ee.
A NEW CHIRAL HOST COMPOUND 10,10'-DIHYDROXY-9,9'-BIPHENANTHRYL. OPTICAL RESOLUTION OF PROPIONIC ACID DERIVATIVES, BUTYRIC ACID DERIVATIVES, AND 4-HYDROXYCYCLOPENT-2-EN-1-ONE DERIVATIVES BY COMPLEXATION
Toda, Fumio,Tanaka, Koichi
, p. 1807 - 1810 (2007/10/02)
Optically active 10,10'-dihydroxy-9,9'-biphenanthryl was designed as a new chiral host compound for optical resolution of guest compounds, and was found to be wery effective for resolution of the title guest compounds.
