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Hydroxymethyl
Terms modified by Hydroxymethyl Selected AbstractsPhotoinduced Formation of Reactive Oxygen Species from the Acid Form of 6-(Hydroxymethyl)pterin in Aqueous SolutionHELVETICA CHIMICA ACTA, Issue 6 2006Andrés Abstract The photochemistry of 6-(hydroxymethyl)pterin (HPT; 1) in aqueous solution (pH 5,6) was investigated by irradiation at 350,nm at room temperature. The photochemical reactions of the acidic form 1a were followed by UV/VIS spectrophotometry, thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and enzymatic methods for the determination of the superoxide anion radical (O) and hydrogen peroxide (H2O2). When 1a is exposed to UV-A radiation, the intermediates 4 and 4, are formed reacting with O2 to yield 6-formylpterin (FPT; 5) and 6-carboxypterin (CPT; 6) under formation of O and H2O2 (Scheme,3). The quantum yields of the disappearance of HPT (1a) and of the formation of the photoproducts 5 and 6 were determined. HPT was investigated for its efficiency in singlet-oxygen (1O2) production in acidic aqueous solution. The corresponding quantum yield of 1O2 production (,,) was 0.15,±,0.02, as measured by the 1O2 luminescence in the near-IR (1270,nm) upon continuous excitation of the sensitizer. However, 1O2 does not participate in the actual photooxidation of HPT (1a) to FPT (5) and CPT (6). [source] Synthesis of Substituted , -(Hydroxymethyl)- , -iodoacrylates via MgI2 -Promoted Stereoselective Aldol CouplingHELVETICA CHIMICA ACTA, Issue 9 2004Han-Xun Wei The efficient and highly stereoselective syntheses of a variety of (Z)-configured, substituted , -(hydroxymethyl) - , -iodo-acrylates from prop-2-ynoate and various aldehydes was achieved. The synthetic protocol involves a simple one-pot coupling reaction under mild conditions, promoted by MgI2, which serves both as a Lewis acid and iodine source for a BaylisHillman -type reaction. All adducts were generated in good-to-excellent yields, the (Z)-isomers being formed in high selectivity (>98%). The conversion of methyl prop-2-ynoate into an active ,, -iodo allenolate' intermediate, which then nucleophilically attacks an aldehyde, is proposed as a plausible reaction mechanism. [source] Ab Initio Structure/Reactivity Investigations of Illudin-Based Antitumor Agents: A Model for Reaction in vivoHELVETICA CHIMICA ACTA, Issue 12 2003Laura (Hydroxymethyl)acylfulvene (HMAF, irofulven; 4), a third-generation derivative of a natural product extracted from the mushroom Omphalotus illudens, is selectively toxic towards certain forms of malignant tumors. Conversion of HMAF and cognates to stable aromatic derivatives is triggered by thiol attack in vitro and in vivo. Quantum-chemical methods predict well the structure for several functionalized derivatives of irofulven as compared to known X-ray crystallographic structures. Computational reaction profiles for thiol attack and aromatic rearrangement of irofulven and illudin S, a toxin from which irofulven is derived, provide insight into HMAF's selectivity and toxicity. Methods used include hybrid density-functional theory (HDFT), HartreeFock (HF), and MřllerPlesset second-order perturbation theory (MP2). Solvent effects have been explored by means of the new continuum-solvation method, COSab, presented in an accompanying paper. [source] Impurities in a morphine sulfate drug product identified as 5-(hydroxymethyl)-2-furfural, 10-hydroxymorphine and 10-oxomorphineJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2003Seán S. Kelly Abstract Stability testing of morphine sulfate formulated with nonpareil sugar seeds (consisting of sucrose and starch) and fumaric acid revealed the formation of the three impurities 5-(hydroxymethyl)-2-furfural, 10-hydroxymorphine and 10-oxomorphine. 5-(Hydroxymethyl)-2-furfural was isolated via semipreparative HPLC utilizing volatile mobile phase constituents and was identified by analysis of its HRMS and NMR spectra. 10-Hydroxymorphine and 10-oxomorphine were obtained via semipreparative HPLC and subsequent removal of ion-pair reagents using an anion exchange resin, or by solid phase extraction, and identified by spectroscopic analysis followed by comparison with authentic materials. 5-(Hydroxymethyl)-2-furfural is a degradation product of hexose sugars, and its formation in the presence of morphine sulfate formulated with fumaric acid suggests that caution should be exercised when including nonpareil seeds in formulations that contain acidic drug salts and/or acid excipients. The preliminary results of tests on the interaction of acidic salts of some other drugs with nonpareil seeds are presented. © 2003 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 92:485,493, 2003 [source] ChemInform Abstract: anti-Diastereo- and Enantioselective Carbonyl (Hydroxymethyl)allylation from the Alcohol or Aldehyde Oxidation Level: Allyl Carbonates as Allylmetal Surrogates.CHEMINFORM, Issue 32 2010Yong Jian Zhang Abstract The first enantioselective carbonyl (hydroxymethyl)allylation in the presence of aromatic, allylic, or aliphatic alcohols (II) is reported employing an (S)-SEGPHOS-modified iridium C,O-benzoate complex to provide products (III) in good isolated yields, good anti-diastereoselectivities and high enantioselectivities. [source] ChemInform Abstract: A Facile Indium-Mediated Synthesis of Protected and Unprotected [1-(Hydroxymethyl)vinyl]alkanols.CHEMINFORM, Issue 28 2009Nimalini D. Moirangthem Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Synthesis of Carbocyclic 1-[4-(Hydroxymethyl)cyclopent-2-enyl]-1,2,4-triazole-3-carboxamide and Its Derivatives.CHEMINFORM, Issue 43 2003Gwang-il An Abstract For Abstract see ChemInform Abstract in Full Text. [source] Concerning Tishchenko-Like Side Products in Oxidation of Hydroxymethyl to Formyl Groups.CHEMINFORM, Issue 40 2003Guo-Zhiwei Guo-Zhiwei Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Excited State Intramolecular Redox Reaction of 2-(Hydroxymethyl)anthraquinone in Aqueous Solution.CHEMINFORM, Issue 19 2002Matthew Lukeman Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Highly Selective Preparation of 2-(Hydroxymethyl)vinylphosphonates by Insertion of Ketones into Zirconacycle Phosphonates.CHEMINFORM, Issue 18 2002Abed Al Aziz Quntar Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Formaldehyde-releasers: Relationship to formaldehyde contact allergy, Part 2: Metalworking fluids and remainderCONTACT DERMATITIS, Issue 3 2010Anton De Groot We have reviewed formaldehyde-releasers used in metalworking fluids (MWFs) in this and a previous part of a two-part article. These biocides do not appear to be frequent or important sensitizers. Even in highly selected patient groups of metalworkers, mean prevalence rates of sensitivity are low: 0.2% for Tris(hydroxymethyl)nitromethane, 1.6% for tris(N -hydroxyethyl)hexahydrotriazine, 1.9% for Bioban® P-1487 and Bioban® CS-1246, and 2.8% for Bioban® CS-1135. In the case of the Biobans, many reactions may have been irritant. Only N,N,-methylenebis(5-methyloxazolidine) has a fairly high mean score of 4.0% in metalworkers. With the exception of Bioban® P-1487, there is a clear relationship between positive patch test reactions to the releasers and formaldehyde sensitivity: 40,70% of reactions to releasers occur in patients sensitive to formaldehyde and may therefore be caused by formaldehyde allergy. There is a lack of reliable data on the clinical relevance of contact allergy to the formaldehyde releasers in MWF. In most studies, no data on relevance were provided and in those that did, relevance was often found for a (very small) minority of the reactions only. Also discussed here are the formaldehyde-releasers MDM hydantoin, methenamine, N -methylolchloracetamide, paraformaldehyde, and Preventol® D2. [source] Pretreatment with insulin before ischaemia reduces infarct size in Langendorff-perfused rat heartsACTA PHYSIOLOGICA, Issue 2 2009B. N. Fuglesteg Abstract Aim:, To compare the possible role of Akt and mammalian target of rapamycin (mTOR) in mediating cardioprotection against ischaemia under three different conditions: (1) During ischaemic preconditioning (IPC), (2) when insulin was given as a pretreatment agent (InsPC) and (3) when insulin was given as a reperfusion cell survival agent (InsR). Methods:, Isolated perfused rat hearts were subjected to IPC (3 × 5 min) or InsPC (50 mU mL,1; 3 × 5 min), before 30 min of regional ischaemia followed by 120 min of reperfusion ± 1L-6-hydroxymethyl- chiro -inositol-2 - [(R)-2- O -methyl-3- O -octadecylcarbonate] (HIMO) (20 ,m; Akt inhibitor) or rapamycin (1 nm; mTOR inhibitor). In addition, insulin (3 mU mL,1) was given at the onset of reperfusion, ±HIMO or rapamycin. Risk zone (R) and infarct size (I) were determined with Evans blue and tetrazolium staining respectively. Western blot analysis was performed on tissue from Langendorff-perfused rat hearts and cell lysates from cultured HL1 cells. Results:, IPC, InsPC and InsR treatment resulted in a significant reduction in infarct size compared to controls (all P < 0.05). This protective effect of IPC and insulin was abolished by the inhibitors. However, the putative Akt inhibitor, although capable of abolishing cardioprotection induced by insulin, was not able to inhibit insulin-induced phosphorylation of Akt in Langendorff-perfused rat hearts and cultured HL1 cells. The target for this compound therefore remains to be determined. Conclusion:, IPC and insulin (either as InsPC or InsR) appear to activate mTOR, and this kinase seems to play an essential role in cardioprotection against ischaemia and reperfusion injury as rapamycin blocked the protection. [source] Hydrophobic derivatives of 5-(hydroxymethyl)isophthalic acid that selectively induce apoptosis in leukemia cells but not in fibroblasts,,DRUG DEVELOPMENT RESEARCH, Issue 4 2008Anna Galkin Abstract New apoptosis modulating agents are widely sought, because failure in regulation of apoptosis is associated with many diseases. In this study, we have evaluated apoptosis inducing the potential of ten new hydrophobic derivatives of 5-(hydroxymethyl)isophthalic acid. Cancerous leukemia cells (HL-60) and non-malignant fibroblasts (Swiss 3T3) were incubated with test compounds for 24,h and morphologically evaluated. The changes in mitochondrial membrane potential (,,m) and caspase-3 activity were used to confirm the results and to study early induction of apoptosis. Cytotoxicity was determined using the lactate dehydrogenase (LDH) assay and mutagenicity with miniaturized Ames-test. The most potent selective apoptosis inducers were compounds 1c and 1,h having IC50 values of 41 and 23,µM, respectively, in leukemia cells (HL-60) while effects in fibroblasts (Swiss 3T3) were insignificant. Reduction of ,,m and increase in caspase-3 activity were observed already during the first 2,hr in the HL-60 cells treated with compounds 1,c and 1,h. Neither of the compounds was cytotoxic or mutagenic. The results indicate that compounds 1,c and 1,h are selective apoptosis inducers and should be studied further for possible use in cancer therapy. Drug Dev. Res. 69: 185,195, 2008. © 2008 Wiley-Liss, Inc. [source] Preparative capillary zone electrophoresis using a dynamic coated wide-bore capillaryELECTROPHORESIS, Issue 15 2006Mahmoud M. Yassine Abstract Preparative capillary zone electrophoresis separations of cytochrome,c from bovine and horse heart are performed efficiently in a surfactant-coated capillary. The surfactant, dimethylditetradecylammonium bromide (2C14DAB), effectively eliminated protein adsorption from the capillary surface, such that symmetrical peaks with efficiencies of 0.7,million plates/m were observed in 50-µm,id capillaries when low concentrations of protein were injected. At protein concentrations greater than 1,g/L, electromigration dispersion became the dominant source of band broadening and the peak shape distorted to triangular fronting. Matching of the mobility of the buffer co-ion to that of the cytochrome,c resulted in dramatic improvements in the efficiency and peak shape. Using 100,mM bis(2-hydroxyethyl)imino-tris(hydroxymethyl)methane phosphate buffer at pH,7.0 with a 100-µm,id capillary, the maximum sample loading capacity in a single run was 160,pmol (2.0,µg) of each protein. [source] Determination of the chiral and achiral related substances of methotrexate by cyclodextrin-modified micellar electrokinetic chromatographyELECTROPHORESIS, Issue 16 2004Roberto Gotti Abstract A cyclodextrin-modified micellar electrokinetic chromatographic (CD-MEKC) method for the determination of the most important potential impurities of methotrexate (MTX): 2,4-diamino-6-(hydroxymethyl)pteridine, aminopterine hydrate, 4-[N -(2-amino-4-hydroxy-6-pteridinylmethyl)- N -methylamino] benzoic acid, 4-[N -(2,4-diamino-6-pteridinylmethyl)- N -methylamino] benzoic acid, and the distomer D -MTX is presented. The MEKC separation of these compounds was optimized by applying a step-by-step approach. The addition of ,-CD to a conventional MEKC system, based on sodium dodecyl sulfate (SDS) as surfactant, showed to be essential for the enantioresolution of racemic MTX as well as for the separation of the achiral impurities. To achieve high-resolution factor between the peaks adjacent to the main component (L -MTX), as required in the analysis of related impurities, the separation conditions were stressed; in particular, the addition of methanol to the CD-MEKC system resulted in a very effective choice. Under the optimized final conditions (100 mM SDS and 45 mM ,-CD in a mixture of 50 mM borate buffer, pH 9.30-methanol (75:25 v/v)), the method was validated showing a general adequate accuracy (93,106% recovery) in the determination of L -MTX related substances at the impurity level of 0.12% w/w with a relative standard deviation (RSD)% lower than 8% (n = 4). The method was successfully applied to the analysis of pharmaceuticals (tablets and injections) which showed to contain the distomer D -MTX as major impurity and aminopterine hydrate as a further related substance in the commercial tablets. [source] Stability and detection of ,-pinene oxide in aqueous culture mediumENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2000Kimberly K. Kajihara Abstract Methane consumption by methanotrophic bacteria was previously shown to be temporarily inhibited by ,-pinene. Based on literature considerations, loss of inhibition may be due to bacterial degradation of the monoterpene to ,-pinene oxide, an anticipated metabolite. However, since ,-pinene oxide is unstable in aqueous media, detection of its production by methanotrophs or other bacteria is problematic. Therefore, we used gas chromatography-mass spectrometry analysis to study the chemical breakdown of ,-pinene oxide in various buffer systems (Tris[hydroxymethyl]am inomethane, 3-[N-morpholino]propanesulfonic acid, phosphate; pH 7-9) suitable for bacterial whole-cell and cell-free experiments. In every case, aqueous phase ,-pinene oxide was unstable and its disappearance was accompanied by the appearance of five decomposition products in a characteristic fingerprint that was in part buffer dependent. However, this fingerprint was adequately stable in phosphate buffer such that its appearance could be used to infer the intermediacy of ,-pinene oxide if produced by the bacteria at or near their optimal pH. [source] Oxido Pincer Ligands , Exploring the Coordination Chemistry of Bis(hydroxymethyl)pyridine Ligands for the Late Transition MetalsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2009Axel Klein Abstract Coordination of the 2,6-bis(hydroxymethyl)pyridine-based oxido pincer ligands RR,pydimH2 [R = R, = H (pydimH2); R = R, = Me (pydipH2); R = 2-tolyl, R, = Me (pydotH2)] towards late transition metals CoII, NiII, CuII, ZnII, PdII and PtII allows the formation of molecular species (complexes), which exhibit three main structural motifs in the solid state. The two main species are pentacoordinate [(RR,pydimH2)MCl2] and hexacoordinate [(RR,pydimH2)2M]X2, both of which are stable in solution and can be interconverted by changing the solvent polarity. The disproportionation equilibrium [(RR,pydimH2)MCl2] [rlhar2] [(RR,pydimH2)2M]2+ + [MCl4]2, was studied by optical spectroscopy. The chiral ligand pydotH2 allows the formation of chiral complexes. In the square-planar complexes [(pydimH2)2MCl2] (M = PdII or PtII) the oxido donor functions of the ligands do not take part in the coordination.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Application of New Organic Fuels in the Direct MgAl2O4 Combustion SynthesisEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2008Robert Iano Abstract The paper presents a new version of MgAl2O4 solution-combustion synthesis, based on the individual reactivity of Mg(NO3)2 and Al(NO3)3 with respect to various fuels. Beside the traditionally used fuels (urea, glycine, ,-alanine), new organic reducing agents [monoethanolamine, triethanolamine, tris(hydroxymethyl)aminomethane and triethylenetetramine] have also been used. The study of the individual reactivities of Mg(NO3)2 and Al(NO3)3 with respect to each of the previously mentioned fuels suggested that there is a predilection of the two metal nitrates for certain fuels: urea is the optimum fuel for Al(NO3)3, whereas monoethanolamine represents the most suitable fuel for Mg(NO3)2. It has been shown by X-ray diffraction and thermal analysis that the use of a single fuel in the MgAl2O4 low-temperature combustion synthesis leads to the formation of an amorphous powder. In this case, the formation of pure crystalline MgAl2O4 requires a subsequent thermal treatment at 900 °C with 1 h soaking time. On the other hand, the use of fuel mixtures containing urea and monoethanolamine or urea and ,-alanine proved to be the rational solution for the direct formation of MgAl2O4. It has been shown that, by using the above-mentioned fuel mixtures, one can obtain pure nanocrystalline MgAl2O4 straight from the combustion reaction, no additional calcination being necessary. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Nucleophilic Additions to Cyclic Nitrones en Route to Iminocyclitols , Total Syntheses of DMDP, 6-deoxy-DMDP, DAB-1, CYB-3, Nectrisine, and Radicamine BEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2008Pedro Merino Abstract Highly diastereoselective nucleophilic additions to cyclic nitrones derived from L -malic acid and D -arabinose have been used for the construction of enantiomerically pure polyhydroxylated pyrrolidines. The synthetic strategy adopted was based on an oxidation/reduction protocol involving hydroxylamine/nitrone pairs and demonstrates the use of reagent- and substrate-derived stereocontrol. In most cases reactions took place with total diastereoselectivity and in quantitative yield, with no purification being necessary. By this strategy, 2-(hydroxymethyl)-, 2-(aminomethyl)-, and 2-aryl-substituted polyhydroxylated pyrrolidines have been prepared with abundant configurational diversity. The use of appropriate substrates and reagents allowed for approaches to DMDP, 6-deoxy-DMDP, DAB-1, CYB-3, nectrisine and radicamine B. Several analogues of these compounds with inverted configuration at one or more stereocenters were also prepared.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Palladium-Catalyzed Formation of Cyclic Ethers , Regio-, Stereo- and Enantioselectivity of the ReactionEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2007Anna Zawisza Abstract An efficient and stereoselective synthesis of 3-alkyl-3-hydroxymethyl-5-vinyltetrahydrofurans is described by the Pd0 -catalyzed cyclization of the methyl carbonates of ,,,-bis(hydroxymethyl)-,,,-unsaturated alcohols. The use of chiral ligands gave the corresponding THF derivatives in low to moderate enantiomeric ratios. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] XNA, (xylo Nucleic Acid): A Summary and New DerivativesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2005B. Ravindra Babu Abstract Fully modified homopyrimidine 2'-deoxy- xylo nucleic acid (dXNA) form triple helixes with complementary DNA/RNA with thermal stabilities comparable to those of the corresponding DNA:DNA and DNA:RNA duplexes. However, a single or few insertions of dXNA monomers in a DNA strand significantly lower duplex stabilities. The dXNA monomers are known to adopt predominantly an N -type furanose conformation in solution. With a desire to increase the binding affinity, seven sugar-modified XNA monomers (H, F, N, M, K, P and Q) have been synthesised and their effect on hybridization towards DNA and RNA complements studied. The introduction of 2'-fluoro and 2'-hydroxy substituents was expected to induce conformational restriction towards C3'- endo -type furanose conformation of monomer F derived from 1-(2'-deoxy-2'-fluoro-,- D -xylofuranosyl)thymine and monomer H derived from 1-(,- D -xylofuranosyl)thymine. The presence of functionalites facing the minor groove as in 1-(2'-amino-2'-deoxy-2'- N,4'- C -methylene-,- D -xylofuranosyl)thymine (monomer N), 1-[4- C -(N -methylpiperazinyl)methyl-,- D -xylofuranosyl]thymine (monomer P), 1-(4- C -piperazinylmethyl-,- D -xylofuranosyl)thymine (monomer Q), 1-(4- C -hydroxymethyl-,- D -xylofuranosyl)thymine (monomer M) and 9-(4- C -hydroxymethyl-,- D -xylofuranosyl)adenine (monomer K) was studied, with monomer N being locked in an N -type furanose conformation. Besides, an efficient synthesis of known xylo -LNA phosphoramidite 19, required for the incorporation of 1-(2'- O,4'- C -methylene-,- D -xylofuranosyl)thymine (monomer L) is described. For comparison, hydridization data of various XNAs reported in the literature are included in the discussion section. The thermal denaturation studies show that XNAs containing conformationally locked monomers (N and L) display improved binding affinity, and that partially modified DNA/XNA chimera, or fully modified XNA display preferential hybridization towards RNA complements. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Secondary Metabolites from the Fungus Chaetomium brasilienseHELVETICA CHIMICA ACTA, Issue 1 2008Guo-You Li Abstract Two new depsidones, mollicellins I and J (1 and 2, resp.), and a new chromone, 2-(hydroxymethyl)-6-methylmethyleugenin (3), along with six known compounds, 4,9, were isolated from the ethyl acetate extract of a solid-state fermented culture of Chaetomium brasiliense. Their structures were elucidated based on spectroscopic analysis. Mollicellins I and H (5) exhibited significant growth inhibitory activity against human breast cancer (Bre04), human lung (Lu04), and human neuroma (N04) cell lines with GI50 values between 2.5,8.6,,g/ml. [source] A Synthesis Detour to Planar-Diastereoisomeric Ferrocene Derivatives around an Unexpected Rearrangement of ortho -Lithiated Kagan's Template [S(S)] - (p -Tolylsulfinyl)ferroceneHELVETICA CHIMICA ACTA, Issue 4 2007Immo Weber Abstract Usually, ortho lithiation of Kagan's template 1 and quenching with electrophiles leads highly diastereoselectively to planar-chiral 1,2-disubstituted ferrocenes. Surprisingly, lithiation of 1 with lithium diisopropylamide (LDA) followed by addition of paraformaldehyde afforded regioisomer (+)-{[S(S)] - [4-(2-hydroxyethyl)phenyl]sulfinyl}ferrocene (2), which was converted to (+)-{[S(S)] - {4-{2-[(methylsulfonyl)oxy]ethyl}phenyl}sulfinyl}ferrocene (3) (Scheme,1). The desired diastereoisomer (l)-1-(hydroxymethyl)-2-(p -tolylsulfinyl)ferrocene (5) in turn could also be obtained by ortho lithiation of 1 with LDA but by quenching with DMF to yield aldehyde 4 first, which then was reduced with NaBH4 to 5. Finally, target compound (l)-1-[(dimethylamino)methyl]-2-(p -tolylsulfinyl)ferrocene (6) was obtained by substitution of the OH group of 5 under mild conditions or directly by ortho lithiation of 1 with lithio-2,4,6-triisopropylbenzene (=2,4,6-triisopropylphenyl)lithium; LTP) followed by quenching with N,N -dimethylmethyleneiminium chloride. At low temperatures, reaction of 1 with LDA leads, via the preferred diastereoisomeric transition state ,exo'- 7 and under extrusion of a (diisopropylamine)lithium complex of type 8, in a highly selective manner, to diastereoisomeric ortho -lithiated chelate (l)- 9 (Scheme,2). The reaction of 1 to 2 is explained by a rearrangement of (l)- 9 to {[S(S)],[4-(lithiomethyl)phenyl]sulfinyl}ferrocene 10, which is acid-catalyzed by coordinated diisopropylamine in complexes of type 8. This rearrangement is not observed if LTP is used as base or, in case LDA is applied, if the electrophile is sufficiently reactive at low temperatures. [source] Photoinduced Formation of Reactive Oxygen Species from the Acid Form of 6-(Hydroxymethyl)pterin in Aqueous SolutionHELVETICA CHIMICA ACTA, Issue 6 2006Andrés Abstract The photochemistry of 6-(hydroxymethyl)pterin (HPT; 1) in aqueous solution (pH 5,6) was investigated by irradiation at 350,nm at room temperature. The photochemical reactions of the acidic form 1a were followed by UV/VIS spectrophotometry, thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and enzymatic methods for the determination of the superoxide anion radical (O) and hydrogen peroxide (H2O2). When 1a is exposed to UV-A radiation, the intermediates 4 and 4, are formed reacting with O2 to yield 6-formylpterin (FPT; 5) and 6-carboxypterin (CPT; 6) under formation of O and H2O2 (Scheme,3). The quantum yields of the disappearance of HPT (1a) and of the formation of the photoproducts 5 and 6 were determined. HPT was investigated for its efficiency in singlet-oxygen (1O2) production in acidic aqueous solution. The corresponding quantum yield of 1O2 production (,,) was 0.15,±,0.02, as measured by the 1O2 luminescence in the near-IR (1270,nm) upon continuous excitation of the sensitizer. However, 1O2 does not participate in the actual photooxidation of HPT (1a) to FPT (5) and CPT (6). [source] Squadinorlignoside: A Novel 7,9,-Dinorlignan from the Stems of Annona squamosaHELVETICA CHIMICA ACTA, Issue 10 2005Yu-Liang Yang Two new polar lignans, i.e., squadinorlignoside (=,4-[(1E)-1-(hydroxymethyl)-3-(4-hydroxyphenyl)prop-1-en-1-yl]phenyl , - D -glucopyranoside; 1) and (6R,7R,8S)-7a-[(, - D -glucopyranosyl)oxy]-1-methoxyisolariciresinol (2) were isolated from the stems of Annona squamosa, together with eight known lignans and five known neolignans (compounds 3,15; Fig.,1). All of these constituents are reported for the first time from the genus Annona. The structures, absolute configurations, and selected conformational aspects of the new compounds were elucidated spectroscopically. Compound 1 is the first example of a 7,9,-dinorlignan natural product. [source] Synthesis of Substituted , -(Hydroxymethyl)- , -iodoacrylates via MgI2 -Promoted Stereoselective Aldol CouplingHELVETICA CHIMICA ACTA, Issue 9 2004Han-Xun Wei The efficient and highly stereoselective syntheses of a variety of (Z)-configured, substituted , -(hydroxymethyl) - , -iodo-acrylates from prop-2-ynoate and various aldehydes was achieved. The synthetic protocol involves a simple one-pot coupling reaction under mild conditions, promoted by MgI2, which serves both as a Lewis acid and iodine source for a BaylisHillman -type reaction. All adducts were generated in good-to-excellent yields, the (Z)-isomers being formed in high selectivity (>98%). The conversion of methyl prop-2-ynoate into an active ,, -iodo allenolate' intermediate, which then nucleophilically attacks an aldehyde, is proposed as a plausible reaction mechanism. [source] Paxillamide: a Novel Phytosphingosine Derivative from the Fruiting Bodies of Paxillus panuoidesHELVETICA CHIMICA ACTA, Issue 6 2004Jin-Ming Gao The new phytosphingosine-type ceramide 1, named paxillamide (=2,3-dihydroxy- N -[(1S,2S,3R)-2,3-dihydroxy-1-(hydroxymethyl)heptadecyl]tetracosanamide), was isolated from the CHCl3/MeOH extract of the fruiting bodies of the Basidiomycete Paxillus panuoides, and its structure was elucidated by spectroscopic and chemical methods. [source] New Nonhydrolyzable Mimetics of Sialyl Lewis X and Their Binding Affinity to P-SelectinHELVETICA CHIMICA ACTA, Issue 5 2004Frédéric Carrel Wittig olefination of (2S,3R,5S,6R)-5-(acetyloxy)-tetrahydro-6-[(methoxymethoxy)methyl]-3-(phenylthio)- 2H -pyran-2-acetaldehyde ((+)- 10) with {2-[(2S,3R,4R,5R,6S)-tetrahydro-3,4,5-tris(methoxymethoxy)-6-methyl- 2H -pyran-2-yl]ethyl}triphenylphosphonium iodide ((,)- 11) gave a (Z)-alkene derivative (+)- 12 that was converted into (,R,2R,3S,4R,5R,6S)-tetrahydro- ,,3-dihydroxy-2-(hydroxymethyl)-5-(phenylthio)-6-{(2Z)-4-[(2S,3S,4R,5S,6S)-tetrahydro-3,4,5-trihydroxy-6-methyl-2H -pyran-2-yl]but-2-enyl}2H -pyran-4-acetic acid (8), (,R,2R,3S,4R,6S)-tetrahydro- ,,3-dihydroxy-2-(hydroxymethyl)-6-{4-[(2S,3S,4R,5S,6S)-tetrahydro-3,4,5-trihydroxy-6-methyl-2H -pyran-2-yl]butyl}-2H -pyran-4-acetic acid (9), and simpler analogues without the hydroxyacetic side chain such as (2S,3S,4R,5S,6S)-tetrahydro-6-methyl-2-{(2Z)-4-[(2S,3R,5S,6R)-tetrahydro-5-hydroxy-6-(hydroxymethyl)-3-(phenylthio)-2H -pyran-2-yl]but-2-enyl}-2H -pyran-3,4,5-triol (30), (2S,3S,4R,5S,6S)-tetrahydro-6-methyl-2-{[(2S,5S,6R)-tetrah dro-5-hydroxy-6-(hydroxymethyl)-2H -pyran-2-yl]butyl}-2H -pyran-3,4,5- triol ((,)- 41) and (2S,3S,4R,5S,6S)-tetrahydro-6-methyl-2-{(2Z/E))-4-[(2R,5S,6R)-tetrahydro-5-hydroxy-6-(hydroxymethyl)-2H -pyran-2-yl]but-2-enyl}-2H -pyran-3,4,5-triol (43). The key intermediates (+)- 10 and (,)- 11 were derived from isolevoglucosenone and from L -fucose, respectively. The following IC50 values were measured in a ELISA test for the affinities of sialyl Lewis x tetrasaccharide, 8, 9, 30, (,)- 41, and 43 toward P-selectin: 0.7, 2.5,2.8, 7.3,8.0, 5.3,5.9, 5.0,5.2, and 3.4,4.1,mM, respectively. [source] Controlled Release of Perfumery Alcohols by Neighboring-Group Participation.HELVETICA CHIMICA ACTA, Issue 8 20032-(Hydroxymethyl)-, 2-Carbamoylbenzoates, Comparison of the Rate Constants for the Alkaline Hydrolysis of 2-Acyl- A series of 2-acylbenzoates 1 and 2, 2-(hydroxymethyl)benzoates 3, 2-carbamoylbenzoates 4,6, as well as the carbamoyl esters 7 or 8 of maleate or succinate, respectively (see Fig.,2), were prepared in a few reaction steps, and the potential use of these compounds as chemical delivery systems for the controlled release of primary, secondary, and tertiary fragrance alcohols was investigated. The rate constants for the neighboring-group-assisted alkaline ester hydrolysis were determined by anal. HPLC in buffered H2O/MeCN solution at different pH (Table,1). The rates of hydrolysis were found to depend on the structure of the alcohol, together with the precursor skeleton and the structure of the neighboring nucleophile that attacks the ester function. Primary alcohols were released more rapidly than secondary and tertiary alcohols, and benzoates of allylic primary alcohols (e.g., geraniol) were hydrolyzed 2,4 times faster than their homologous saturated alcohols (e.g., citronellol). For the same leaving alcohol, 2-[(ethylamino)carbonyl]benzoates cyclized faster than the corresponding 2-(hydroxymethyl)benzoates, and much faster than their 2-formyl and 2-acetyl analogues (see, e.g., Fig.,4). Within the carbamoyl ester series, 2-[(ethylamino)carbonyl]benzoates were found to have the highest rate constants for the alkaline ester hydrolysis, followed by unsubstituted 2-(aminocarbonyl)benzoates, or the corresponding isopropyl derivatives. To rationalize the influence of the different structural changes on the hydrolysis kinetics, the experimental data obtained for the 2-[(alkylamino)carbonyl]benzoates were compared with the results of density-functional computer simulations (Table,2 and Scheme,4). Based on a preliminary semi-empirical conformation analysis, density-functional calculations at the B3LYP/6-31G** level were carried out for the starting precursor molecules, several reaction intermediates, and the cyclized phthalimides. For the same precursor skeleton, these simple calculations were found to model the experimental data correctly. With an understanding of the influence of structural parameters on the rate constants obtained in this work, it is now possible to influence the rates of hydrolysis over several orders of magnitude, to design tailor-made precursors for a large variety of fragrance alcohols, and to predict their efficiency as controlled-release systems in practical applications. [source] Release of nucleophosmin from the nucleus: Involvement in aloe-emodin,induced human lung non small carcinoma cell apoptosisINTERNATIONAL JOURNAL OF CANCER, Issue 6 2005Hong-Zin Lee Abstract Aloe-emodin (1,8-dihydroxy-3-(hydroxymethyl)-anthraquinone) is one of the active constituents from the root and rhizome of Rheum palmatum. Our previous study has demonstrated that aloe-emodin induced a significant change in the expression of lung cancer cell apoptosis-related proteins compared to those of control cells. However, the molecular mechanisms underlying the biological effects of aloe-emodin still remain unknown. Based on these reasons, we were interested in the change of aloe-emodin,induced total protein expression by the proteomics technique during aloe-emodin,induced lung cancer cell apoptosis. Our study applied 2D electrophoresis to analyze the proteins involved in aloe-emodin,induced apoptosis in H460 cells. We found that the release of nucleophosmin from the nucleus to the cytosol and the degradation of nucleophosmin were associated with aloe-emodin,induced H460 cell apoptosis. Our study also demonstrated that the gene expression of nucleophosmin remained unchanged after treatment with aloe-emodin. The aloe-emodin,caused increase in the amount of proform and fragment of nucleophosmin in cytoplasm may be one of the important events for aloe-emodin,induced H460 cell apoptosis. © 2004 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||||||||