Synthesis and characterisation of an enantiomerically pure scandium pentadienyl complex and its application in the polymerisation of rac-lactide

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.

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20050361 ◽

2005 ◽

Vol 70 (3) ◽

pp. 361-369 ◽

Cited By ~ 5

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.

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20061470 ◽

2006 ◽

Vol 71 (10) ◽

pp. 1470-1483 ◽

Cited By ~ 3

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.

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20040885 ◽

2004 ◽

Vol 69 (4) ◽

pp. 885-896 ◽

Cited By ~ 8

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.

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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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20020353 ◽

2002 ◽

Vol 67 (3) ◽

pp. 353-364 ◽

Cited By ~ 3

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.

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