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Methyl P (methyl + p)
Selected AbstractsDiastereomers (RC,SP)- and (RC,RP)- S -methyl P -(3-azidopropyl)- N -[(1R)-1-phenylethyl]phosphonamidothioateACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009Lilu Guo Diastereoisomers of the title organophosphorus compound, C12H19N4OPS, denoted RCSP, (I), and RCRP, (II), were structurally characterized and compared. Asymmetric phosphorus compounds are of interest with regard to the use of these systems as possible protein probes via the stereoselective delivery of an azide group tethered to the P atom into key protein regions. The diastereomers were produced in a 1:1 mixture and isolated by chromatography. Although both isomers crystallize in the same space group with superficially similar cell constants, conformational and packing differences are pronounced. Despite the conformational differences, strong intermolecular hydrogen bonding links both isomers into chains parallel to the a axis [N...O = 2.8609,(18) and 2.966,(3),Å in (I) and (II), respectively], with C,H..., interchain interactions of ca 3.5,Å. [source] Improved Synthesis and Isolation of 2,- O -Methyladenosine: Effective and Scalable Enzymatic Separation of 2,/3,- O -Methyladenosine RegioisomersEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2009Saúl Martínez-Montero Abstract An efficient separation of a mixture of 2,/3,- O -methyladenosine regioisomers (1 + 2; 1:1) has been developed by selective enzymatic acylation using immobilized Pseudomonas cepacia lipase (PSL-C) in combination with acetonoxime levulinate as acyl donor. The 3,-hydroxy group of 2,- O -methyladenosine (1) was acylated with high selectivity (ca. 70,%), whereas an equal amount of 3,- O -methyladenosine (2) in the same solution resulted in minor acylation of 5,-hydroxy group (ca. 8,%). The differential behavior of both regioisomers towards enzymatic acylation allowed to develop a separation protocol. Upon extraction of the acylated products, the 3,- O -methyladenosine was isolated in 81,% yield and 97,% purity from the aqueous layer. Hydrolysis of acylated products in organic layer furnished 2,- O -methyladenosine in 67,% yield and 99,% purity. The separation process was successfully applied to the crude reaction mixture of methylated products (ca. 3:1 of 1/2) on 5-g scale. We also report on the use of methyl p -toluenesulfonate as a safe reagent for 2,- O -methylation of adenosine.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Preparation and Reactivity of Chalcogenyl Phosphonates and Phosphane OxidesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 29 2007Claudio C. Silveira Abstract The preparation of new bis[(diphenylphosphinoyl)methyl] sulfides, selenides, and tellurides is described by the reaction of (diphenylphosphinoyl)methyl p -toluenesulfonate with sodium chalcogenides. The title compounds are subjected to Horner,Wittig-type reactions with aldehydes and ketones to give symmetrical divinylic sulfides, selenides, and tellurides with preferential (E) stereochemistry. Unsymmetrical divinylic sulfides can be prepared by the use of an appropriate carbonyl compound.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] The Hammett equation applied to the nucleophilic displacement of ions and ion pairs on substituted benzenesulphonatesJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 5 2001Sergio Alunni Abstract Nucleophilic substitution on meta - and para -substituted methyl benzenesulphonates was studied with two chloride salts with different structures: NBu4Cl or KCl-Kryptofix 2,2,2. Treating the results with the Acree equation shows that the reaction proceeds by two reaction paths, one involving the chloride ion and the other, slower one, involving the ion pairs. Treating the results with the Hammett equation gives consistent data, and shows that , is positive and nearly the same for the two reaction paths (,,,,+2). The reactivity of methyl p -nitrobenzenesulphonate was compared with that of the corresponding ethyl derivative, and it is shown that the methyl derivative reacts faster than the ethyl derivative in both paths. The results are interpreted based on the assumption that in both paths a negative charge is developed on the leaving group in the transition state, and that the activated complex is linear. Copyright © 2001 John Wiley and Sons, Ltd. [source] Control of Penicillium roqueforti (Thom) infection in cultures of Drosophila melanogaster (Meigen) (Diptera: Drosophilidae)AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 2 2008Clare E Holleley Abstract, Microbial contamination of artificial insect food media can jeopardise the viability, productivity and survival of many insect cultures, including Drosophila melanogaster. Here we investigated and improved upon control methods for one common contaminant, Penicillium roqueforti. We found that the combined effect of methyl p -hydroxybenzoate (23.7 mM), propionic acid (67.5 mM) and sorbic acid (8.9 mM) (PSNPS treatment) was the most effective of the four candidate treatments, at inhibiting the growth of P. roqueforti. PSNPS treatment inhibited 100% of visible P. roqueforti growth for 21 days (a complete D. melanogaster life cycle) and thus reduced the risk of transmitting infection to the next generation. Although the PSNPS treatment negatively affected the two D. melanogaster fitness components, survivorship (number of adults) and biomass (live weight), it did not prevent successful reproduction and is suitable for short-term treatment of P. roqueforti infections. [source] Imination of Sulfides and Sulfoxides with Sulfonylimino-,3 -Bromane under Mild, Metal-Free ConditionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2010Masahito Ochiai Prof. Abstract Exposure of sulfides and sulfoxides to trifluoromethanesulfonylimino(aryl)-,3 -bromane in dichloromethane at 0,°C results in a facile transfer of the sulfonylimino group to sulfur atoms and affords N -triflylsulfilimines and - sulfoximines in high yields under transition-metal-free conditions. Imination of (R)-methyl p -tolyl sulfoxide proceeded with predominant retention of configuration at the stereogenic sulfur center. The Hammett plot afforded , values of ,0.58 for para -substituted thioanisoles and ,0.49 for their equivalent sulfoxides, which suggests a buildup of positive charge on the sulfur atoms of sulfides and sulfoxides in the transition state. Calculations suggest a bimolecular nucleophilic-substitution mechanism on the negatively charged nitrogen atom of the sulfonylimino-,3 -bromane, which involves the attack of a sulfide from the opposite side to bromine(III). [source] | ||||||||||