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Corresponding Methyl Esters (corresponding + methyl_ester)
Selected AbstractsA Novel Direct Conversion of Primary Amides to Their Corresponding Methyl EstersEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2007Liang-Chun Li Abstract A novel method was used to directly convert aliphatic and aromatic primary amides into their corresponding methyl esters in high yields (up to 99,%) under mild reaction conditions. Possible mechanisms were studied at the B3LYP/6-31++G(d,p) level of theory. Formation of the ester proceeded through a rearrangement of the ,OMe and ,NH2 groups in the RC(O)NHS(O)OMe intermediate in a H+ -catalyzed six-membered ring transition state structure. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] 3-[5-(4-Chlorophenyl)-1-(4-methoxyphenyl)-1H -pyrazol-3-yl]propionic acid and the corresponding methyl esterACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009Isuru R. Kumarasinghe The synthesis of 3-[5-(4-chlorophenyl)-1-(4-methoxyphenyl)-1H -pyrazol-3-yl]propionic acid, C19H17ClN2O3, (I), and its corresponding methyl ester, methyl 3-[5-(4-chlorophenyl)-1-(4-methoxyphenyl)-1H -pyrazol-3-yl]propionate, C20H19ClN2O3, (II), is regiospecific. However, correct identification of the regioisomer formed by spectroscopic techniques is not trivial and single-crystal X-ray analysis provided the only means of unambiguous structure determination. Compound (I) crystallizes with Z, = 2. The propionic acid groups of the two crystallographically unique molecules form a hydrogen-bonded dimer, as is typical of carboxylic acid groups in the solid state. Conformational differences between the methoxybenzene and pyrazole rings give rise to two unique molecules. The structure of (II) features just one molecule in the asymmetric unit and the crystal packing makes greater use than (I) of weak C,H...A interactions, despite the lack of any functional groups for classical hydrogen bonding. [source] A Novel Direct Conversion of Primary Amides to Their Corresponding Methyl EstersEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2007Liang-Chun Li Abstract A novel method was used to directly convert aliphatic and aromatic primary amides into their corresponding methyl esters in high yields (up to 99,%) under mild reaction conditions. Possible mechanisms were studied at the B3LYP/6-31++G(d,p) level of theory. Formation of the ester proceeded through a rearrangement of the ,OMe and ,NH2 groups in the RC(O)NHS(O)OMe intermediate in a H+ -catalyzed six-membered ring transition state structure. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] The First General and Selective Palladium(II)-Catalyzed Alkoxycarbonylation of Arylboronates: Interplay among Benzoquinone-Ligated Palladium(0) Complex, Organoboron, and Alcohol SolventADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010Yoshihiko Yamamoto Abstract Methoxycarbonylation of aryl- and alkenylboron compounds was performed using the palladium(II) acetate/triphenylphosphine [Pd(OAc)2/PPh3] catalyst with p -benzoquinone as a stoichiometric oxidant in methanol at ambient temperature to obtain the corresponding methyl esters in good yields. A wide variety of functional groups including various carbonyl functionalities, nitrile, nitro, sulfone, and unprotected pyrrole rings were tolerated in the methoxycarbonlation, while the use of higher alcohols except for tert -butanol afforded various p -chlorobenzoates in moderate to high yields. The catalytic alkoxycarbonylation proceeded without any acid or base additive, and an oxidative transmetalation step is proposed to explain the exceptional efficacy of this protocol. DFT and MP2 calculations support the proposed mechanism. [source] Methyl esters of N -(dicyclohexyl)acetyl-piperidine-4-(benzylidene-4-carboxylic acids) as drugs and prodrugs: A new strategy for dual inhibition of 5,-reductase type 1 and type 2JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 3 2005Martina Streiber Abstract Steroid 5,-reductase (5,R) inhibitory potency of three N -(dicyclohexyl)acetyl-piperidine-4-(benzylidene-4-carboxylic acids) and their corresponding methyl esters was monitored for type 2 isoenzyme in a benign prostatic hyperplasia cell free preparation and for type 1 isoenzyme in DU145 cells and in a cell free assay. The hydrolytic stability of the esters and their bioconversion to the corresponding acids was assessed in aqueous buffered solution (pH 7.4) and in selected biological media having measurable esterase activities. The carboxylic acids 1, 2, and 3 with high type 2 inhibitory potencies displayed only little type 1 inhibition. The esters 1a, 2a, and 3a, originally designed as prodrugs to enhance cell permeation, proved to be potent type 1 inhibitors and are therefore acting as drugs themselves. They are stable in buffered salt solution (pH 7.4), Caco-2 cells, and human plasma, whereas all esters are cleaved into the corresponding acids in benign prostatic hyperplasia tissue homogenate. Methyl esters, applied as hydrolytically stable precursor drugs to facilitate cell permeation, will yield the corresponding carboxylic acids as type 2 inhibitors after hydrolysis in the target organ. The esters themselves,stable in human plasma and Caco-2 cells,are acting as potent drugs toward 5,R type 1. Thus, dual inhibition of 5,R type 1 and type 2 can be achieved by applying a single parent compound. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:473,480, 2005 [source] Absolute configurations of chiral herbicides determined from vibrational circular dichroismCHIRALITY, Issue S1 2005Jiangtao He Abstract Enantiopure herbicides (+)-2-(4-chloro-2-methylphenoxy) propanoic acid, (+)- 1 and (+)-2-(2,4-dichlorophenoxy) propanoic acid, (+)- 2 were investigated using vibrational circular dichroism (VCD). Experimental absorption and VCD spectra of (+)- 1 and (+)- 2 in CDCl3 solution in the 2000,900 cm,1 region were compared with the ab initio predictions of absorption and VCD spectra obtained with density functional theory using the B3LYP/6-31G* basis set for different conformers of (R)- 1 and (R)- 2. Due to the intermolecular hydrogen bonding, this comparison did not provide unambiguous conclusions. To eliminate intermolecular hydrogen bonding influence, the two acids 1 and 2 were converted to the corresponding methyl esters, namely, (+)-methyl 2-(4-chloro-2-methylphenoxy) propanoate, (+)- 3 and (+)-methyl 2-(2,4-dichlorophenoxy) propanoate, (+)- 4. The experimental VCD spectra were measured for these esters and ab initio calculations for different conformers of (R)- 3 and (R)- 4 were carried out. The experimental VCD spectra and corresponding population-weighted theoretical VCD spectra were found to be in excellent agreement, which allowed unambiguous determination of absolute configuration of 3 and 4 as (+)-(R). Since esterification does not invert the configuration, the absolute configuration of the parent acids 1 and 2 is the same as that of corresponding methyl esters. Chirality 17:S1,S8, 2005. © 2004 Wiley-Liss, Inc. [source] | ||||||||||