نتایج جستجو برای: stereoselectively

تعداد نتایج: 274  

Journal: :Drug metabolism and disposition: the biological fate of chemicals 1998
C Longin-Sauvageon V Lattard C Lilaz-Michel T Buronfosse E Benoit

Five different members of the flavin-dependent monooxygenase gene family from different animal species have been described to date. We report the purification and characterization of two FMOs from sheep liver. The predominant isoform was purified 240-fold and was homogenous in SDS PAGE. Its molecular weight (MW) was 58 KDa. The N-terminal sequence, the cross-reactivity with anti-rat FMO3 antibo...

Journal: :Toxicological sciences : an official journal of the Society of Toxicology 2011
Crystal J J Lee Norio Shibata Michael J Wiley Peter G Wells

The expanding therapeutic uses of thalidomide (TD) are limited by its teratogenic side effects. Although the therapeutic and teratogenic effects may be stereoselectively separable, rapid in vivo racemization of the TD isomers confounds the corroboration of this distinction. Herein we evaluated the potential of fluorothalidomide (FTD), the closest structural analog of TD with stable, nonracemizi...

2016
Jakub Saadi Christoph Bentz Kai Redies Dieter Lentz Reinhold Zimmer Hans-Ulrich Reissig

Starting from γ-ketoesters with an o-iodobenzyl group we studied a palladium-catalyzed cyclization process that stereoselectively led to bi- and tricyclic compounds in moderate to excellent yields. Four X-ray crystal structure analyses unequivocally defined the structure of crucial cyclization products. The relative configuration of the precursor compounds is essentially transferred to that of ...

2013
Gholamreza Asghari George Brian Lockwood

The enzymatic potential of the cultured plant cells can be employed for bioconversion purposes. Plant enzymes are able to catalyze regioand stereo-specific reactions, and therefore can be applied for the production of desired substances. The biotransformation of foreign substrates with suspension cells of Peganum harmala was tested with (±) phenylethyl propionate. The callus cultures of Peganum...

Journal: :The Journal of organic chemistry 2002
Alejandro F Barrero J Enrique Oltra Míriam Alvarez Antonio Rosales

The title compounds are interesting candidates for antifungal screening. This paper describes the enantiospecific synthesis of these compounds starting from (+)-costunolide isolated from a commercially available extract. We used two novel reactions as key synthetic steps in this work: the acid-induced cyclization of an delta,epsilon-epoxy ester, which stereoselectively gave a hydroxymethyl-subs...

2017
Vincenzo Piccialli Nicola Borbone Giorgia Oliviero Gennaro Piccialli Stefano D'Errico Roberto Centore

The title compound, C12H20N4O5, crystallizes in the monoclinic space group P21, with four crystallographically independent mol-ecules in the asymmetric unit. The four mol-ecules have a very similar conformation that is basically determined by the formation of two intra-molecular hydrogen bonds between the amino NH2 donors and the carbonyl and ring O-atom acceptors, forming, respectively, R(6) a...

Journal: :Chemical & pharmaceutical bulletin 2001
A Hasuoka Y Nakayama M Adachi H Kamiguchi K Kamiyama

A stereoselective practical synthetic route to indolmycin is described. The route is composed of the regioselective coupling of indolyl magnesium halide with a trans-epoxy ester, diastereoselective oxazolone ring formation with guanidine and amine exchange reaction with methylamine. In the coupling step, use of dichloromethane as co-solvent and conversion of the resulting hydroxy ester to the h...

Journal: :Carbohydrate research 2001
I I Cubero M T López-Espinosa R R Díaz F F Montalbán

Either 3-O-benzoyl- (2a) or 3-O-benzyl-1,2-O-isopropylidene-beta-D-fructopyranose (2b) were regioselectively O-benzylated at C-4 to give 4a and 4b, respectively, which were transformed into 5-azido-3-O-benzoyl-4-O-benzyl- (6a) and 5-azido-3,4-di-O-benzyl-5-deoxy-1,2-O-isopropylidene-alpha-L-sorbopyranose (6b) by nucleophilic displacement of the corresponding 5-O-mesyl derivatives 5a and 5b by s...

2012
Nicole Zimmermann Robert Hilgraf Lutz Lehmann Daniel Ibarra Wittko Francke

Starting from the enantiomers of limonene, all eight stereoisomers of trans-fused dihydronepetalactones were synthesized. Key compounds were pure stereoisomers of 1-acetoxymethyl-2-methyl-5-(2-hydroxy-1-methylethyl)-1-cyclopentene. The stereogenic center of limonene was retained at position 4a of the target compounds and used to stereoselectively control the introduction of the other chiral cen...

2011
Jean-François Brazeau

Introduction One of the long-term objectives of our research program is to contribute at strategic, tactical and theoretical levels with approaches leading to the creation of new stereogenic centers, notably on acyclic molecules, which as a class are among the most difficult chemical entities to transform stereoselectively due to their flexibility. Of particular interest to us is the use of fre...

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