scholarly journals Enantiomerically Pure Pentadienyl Rhodium(I) and Iridium(I) Complexes - Their Synthesis and Reactivity

2019 ◽  
Vol 2019 (36) ◽  
pp. 3954-3961 ◽  
Author(s):  
Ann Christin Fecker ◽  
Katharina Münster ◽  
Matthias Freytag ◽  
Peter G. Jones ◽  
Marc D. Walter
Keyword(s):  
Enantiomerically Pure

Enzymatic Synthesis of Enantiomerically Pure Chiral Synthons: Lipase-Catalyzed Resolution of (R/S, 4E)-2-Methyl-4-hexen-l-ol

Synlett ◽  
1991 ◽  
Vol 1991 (04) ◽  
pp. 310-312
Author(s):  
Patrizia Ferraboschi ◽  
Daria Brembilla ◽  
Paride Grisenti ◽  
Enzo Santaniello
Keyword(s):  
Enzymatic Synthesis ◽  
Enantiomerically Pure

Indium Bromide-catalyzed Unprecedented Hydrogenolysis: A Novel One-Pot Synthesis of Per-O-Acetylated β-carboxymethyl O and S-glycosides

2020 ◽  
Vol 24 (8) ◽  
pp. 900-908
Author(s):  
Ram Naresh Yadav ◽  
Amrendra K Singh ◽  
Bimal Banik
Keyword(s):  
Asymmetric Synthesis ◽  
Chiral Auxiliary ◽  
Bioactive Molecules ◽  
One Pot ◽  
Enantiomerically Pure ◽  
Stereoselective Glycosylation ◽  
One Pot Synthesis ◽  
Wide Range

Numerous O (oxa)- and S (thia)-glycosyl esters and their analogous glycosyl acids have been accomplished through stereoselective glycosylation of various peracetylated bromo sugar with benzyl glycolate using InBr3 as a glycosyl promotor followed by in situ hydrogenolysis of resulting glycosyl ester. A tandem glycosylating and hydrogenolytic activity of InBr3 has been successfully investigated in a one-pot procedure. The resulting synthetically valuable and virtually unexplored class of β-CMGL (glycosyl acids) could serve as an excellent potential chiral auxiliary in the asymmetric synthesis of a wide range of enantiomerically pure medicinally prevalent β-lactams and other bioactive molecules of diverse medicinal interest.

P-Chiral 2-{1'-[Butyl(phenyl)phosphanyl]ferrocen-1-yl}-4-isopropyl-4,5-dihydrooxazoles: A Second Chirality Center in Catalytic System

2005 ◽  
Vol 70 (3) ◽  
pp. 361-369 ◽  
Author(s):  
Dušan Drahoňovský ◽  
Petr Štěpnička ◽  
Dalimil Dvořák
Keyword(s):  
Catalytic System ◽  
Asymmetric Induction ◽  
Dimethyl Malonate ◽  
Enantiomerically Pure

P-Chiral (S,RP)-2-{1'-[butyl(phenyl)phosphanyl]ferrocen-1-yl}-4-isopropyl-4,5-dihydrooxazole (6) and (S,SP)-2-{1'-[butyl(phenyl)phosphanyl]ferrocen-1-yl}-4-isopropyl-4,5-dihydrooxazole (7) were prepared by the procedure developed by Jugé, starting from enantiomerically pure (-)- or (+)-ephedrine and dichloro(phenyl)phosphine. Compounds 6 and 7 were examined for asymmetric induction in the Pd-catalyzed reaction of rac-1,3-diphenylallyl acetate with dimethyl malonate. The best results were obtained with 7 (98% ee), while 6 gave 82% ee.

Synthesis and Structure Assignment of 2-(4-Methoxybenzyl)cyclohexyl β-D-Glucopyranoside Enantiomers

2006 ◽  
Vol 71 (10) ◽  
pp. 1470-1483 ◽  
Author(s):  
David Šaman ◽  
Pavel Kratina ◽  
Jitka Moravcová ◽  
Martina Wimmerová ◽  
Zdeněk Wimmer
Keyword(s):  
Analytical Data ◽  
Chiral Hplc ◽  
Nmr Analysis ◽  
Target Structure ◽  
Enantiomerically Pure ◽  
Whole Cells ◽  
H Nmr ◽  
Structure Assignment ◽  
Related Compounds ◽  
C Nmr

Glucosylation of the cis- and trans-isomers of 2-(4-methoxybenzyl)cyclohexan-1-ol (1a/1b, 2a/2b, 1a or 2a) was performed to prepare the corresponding alkyl β-D-glucopyranosides, mainly to get analytical data of pure enantiomers of the glucosides (3a-6b), required for subsequent investigations of related compounds with biological activity. One of the employed modifications of the Koenigs-Knorr synthesis resulted in achieving 85-95% yields of pure β-anomers 3a/3b, 4a/4b, 3a or 4a of protected intermediates, with several promoters and toluene as solvent, yielding finally the deprotected products 5a/5b, 6a/6b, 5a or 6a as pure β-anomers. To obtain enantiomerically pure β-anomers of the target structure (3a, 4a, 5a and 6a) for unambiguous structure assignment, an enzymic reduction of 2-(4-methoxybenzyl)cyclohexan-1-one by Saccharomyces cerevisiae whole cells was performed to get (1S,2S)- and (1S,2R)-enantiomers (1a and 2a) of 2-(4-methoxybenzyl)cyclohexan-1-ol. The opposite enantiomers of alkyl β-D-glucopyranosides (5b and 6b) were obtained by separation of the diastereoisomeric mixtures 5a/5b and 6a/6b by chiral HPLC. All stereoisomers of the products (3a-6b) were subjected to a detailed 1H NMR and 13C NMR analysis.

Photophysical Characterisation, Metal Ion Binding and Enantiomeric Recognition of Chiral Ligands Containing Phenazine Fluorophore

2004 ◽  
Vol 69 (4) ◽  
pp. 885-896 ◽  
Author(s):  
Luisa Stella Dolci ◽  
Péter Huszthy ◽  
Erika Samu ◽  
Marco Montalti ◽  
Luca Prodi ◽  
...  
Keyword(s):  
Metal Ion ◽  
Photophysical Properties ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Ammonium Ions ◽  
Enantiomerically Pure ◽  
Binding Process ◽  
High Affinity ◽  
Enantiomeric Recognition ◽  
Chiral Species

Enantiomerically pure dimethyl- and diisobutyl-substituted phenazino-18-crown-6 ligands bind metal and ammonium ions and also primary aralkylammonium perchlorates in acetonitrile with high affinity, causing pronounced changes in their luminescence properties. In addition, they show enantioselectivity towards chiral primary aralkylammonium perchlorates. The possibility to monitor the binding process by photoluminescence spectroscopy can gain ground for the design of very efficient enantioselective chemosensors for chiral species. The observed changes in the photophysical properties are also an important tool for understanding the interactions present in the adduct.

π-Facial Selectivity in 1,3-Dipolar Cycloaddition Reactions of α-Methylidene-γ-lactone Substituted by 4-Methyl-2,6,7-trioxabicyclo[2.2.2]octan-1-yl Group in γ-Position

2002 ◽  
Vol 67 (3) ◽  
pp. 353-364 ◽  
Author(s):  
Petr Melša ◽  
Ctibor Mazal
Keyword(s):  
Double Bond ◽  
Carboxylic Acid ◽  
Nitrile Oxide ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Enantiomerically Pure ◽  
Nitrile Imine ◽  
Facial Selectivity ◽  
Excellent Selectivity

Diastereoselectivity of 1,3-dipolar cycloaddition reactions of benzyl azide, diazomethane, a nitrile oxide and a nitrile imine to α-methylidene-γ-lactone dipolarophile was effectively controlled by a bulky γ-substituent, 4-methyl-2,6,7-trioxabicyclo[2.2.2]octan-1-yl in γ-position of the dipolarophile. The dipoles added from the less hindered face of the double bond with an excellent selectivity. Enantiomerically pure dipolarophile was prepared from the easily available (S)-5-oxotetrahydrohydrofuran-2-carboxylic acid.

scholarly journals Enzymatic Approach to the Synthesis of Enantiomerically Pure Hydroxy Derivatives of 1,3,5-Triaza-7-phosphaadamantane

2021 ◽  
Author(s):  
Małgorzata Kwiatkowska ◽  
Jarosław Błaszczyk ◽  
Lesław Sieroń ◽  
Piotr Kiełbasiński
Keyword(s):  
Enantiomerically Pure ◽  
Derivatives Of

scholarly journals Altering the Stereoselectivity of Whole-Cell Biotransformations via the Physicochemical Parameters Impacting the Processes

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 781
Author(s):  
Agnieszka Raczyńska ◽  
Joanna Jadczyk ◽  
Małgorzata Brzezińska-Rodak
Keyword(s):  
Culture Conditions ◽  
Biologically Active ◽  
Enantiomerically Pure ◽  
Whole Cells ◽  
Chiral Compounds ◽  
Physicochemical Factors ◽  
Pure Compounds ◽  
Genetic Level ◽  
Prochiral Ketones ◽  
Optically Pure

The enantioselective synthesis of organic compounds is one of the great challenges in organic synthetic chemistry due to its importance for the acquisition of biologically active derivatives, e.g., pharmaceuticals, agrochemicals, and others. This is why biological systems are increasingly applied as tools for chiral compounds synthesis or modification. The use of whole cells of “wild-type” microorganisms is one possible approach, especially as some methods allow improving the conversion degrees and controlling the stereoselectivity of the reaction without the need to introduce changes at the genetic level. Simple manipulation of the culture conditions, the form of a biocatalyst, or the appropriate composition of the biotransformation medium makes it possible to obtain optically pure products in a cheap, safe, and environmentally friendly manner. This review contains selected examples of the influence of physicochemical factors on the stereochemistry of the biocatalytic preparation of enantiomerically pure compounds, which is undertaken through kinetically controlled separation of their racemic mixtures or reduction of prochiral ketones and has an effect on the final enantiomeric purity and enantioselectivity of the reaction.

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