Cinchona alkaloids and their derivatives can catalyze an amazing array of synthetically important reactions, providing access to chiral products high enantiopurity. A review such asymmetric comprising the work reported in last two decades, is presented here. alkaloids-derived catalysts ligands, either monomeric form or attached a polymeric support, are included this review.

Abstract Pig liver esterase‐(PLE) catalyzed hydrolysis of dimethyl esters symmetrical dicarboxylic acids, including meso ‐diacids, cis ‐1,2‐cycloalkanedicarboxylic and diacids with a prochiral center, was studied 14 substrates. The products these stereoselective hydrolyses are chiral monoesters an enantiomeric excess (e.e.) from 10% to 100%. Some optically active valuable synthons in natural synthesis. An additivity pattern α‐ β‐substituents the glutaric on stereoselectivity enzymatic...

Triangular 30- and 27-membered hexaiminomacrocycles 4 5 of D(3) C(3) symmetry, respectively, are readily obtained by unprecedented [3 + 3] cyclocondensation (R,R)-1, 2-diaminocyclohexane with, accordingly, terephthalaldehyde isophthalaldehyde. The course the reaction, leading to macrocyclization, is governed conformational constraints imposed on structural components intermediate products, as shown molecular modeling. X-ray analysis cocrystal 4.AcOEt revealed that macrocycle symmetry...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComplementarity and chiral recognition: enantioselective complexation of bilirubinDavid A. Lightner, Jacek K. Gawronski, W. M. Donald WijekoonCite this: J. Am. Chem. Soc. 1987, 109, 21, 6354–6362Publication Date (Print):October 1, 1987Publication History Published online1 May 2002Published inissue 1 October 1987https://pubs.acs.org/doi/10.1021/ja00255a020https://doi.org/10.1021/ja00255a020research-articleACS PublicationsRequest reuse...

An exceptionally large size cuboctahedral imine cage is obtained from small organic molecules in a thermodynamically driven [8+12] cyclocondensation. This demonstration of the role entropy symmetry as driving force reversible reactions.

Thermodynamically driven cyclocondensation of (R,R)-1,2-diaminocyclohexane and 1,3,5-triformylbenzene yields solely a [4 + 6] spherand type product. This is unique example spontaneous formation an organic compound permanent chiral tetrahedral (T) symmetry.

Abstract magnified image Chiral macrocyclic tetra‐ and hexamine macrocycles derived from trans ‐1,2‐diaminocyclohexane (DACH) in complexes with diethylzinc efficiently catalyze the asymmetric hydrosilylation of aryl alkyl ketones enantiomeric excess product up to 89%. The cyclic structure trianglamine ligand increases enantioselectivity reaction, comparison catalysis acyclic N,N′ ‐dibenzyl‐DACH ligand. Density functional theory (DFT) computations on structures ligand‐zinc these a coordinated...

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTSimple Circular Dichroic Method for the Determination of Absolute Configuration 5-Substituted 2(5H)-FuranonesJacek K. Gawronski, Arjan van Oeveren, Hanncke der Deen, Chiu W. Leung, and Ben L. FeringaView Author Information Department Chemistry, A. Mickiewicz University, 60-780 Poznañ, Poland, Organic Molecular Inorganic Groningen Centre Catalysis Synthesis, University Groningen, Nijenborgh 4, 9747 AG Netherlands Cite this: J. Org. Chem. 1996, 61,...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChiral carbenoids: their formation and reactionsM. Topolski, M. Duraisamy, J. Rachon, Gawronski, K. Gawronska, V. Goedken, H. WalborskyCite this: Org. Chem. 1993, 58, 3, 546–555Publication Date (Print):January 1, 1993Publication History Published online1 May 2002Published inissue 1 January 1993https://pubs.acs.org/doi/10.1021/jo00055a004https://doi.org/10.1021/jo00055a004research-articleACS PublicationsRequest reuse permissionsArticle...

Trianglamines, macrocyclic heteraphanes, were readily synthesised through a [3+3] cyclocondensation of (R,R)-1,2-diaminocyclohexane with terephthalaldehyde, followed by NaBH4 reduction and N-alkylation. The ring shows remarkable ability to change its conformation, as consequence rotation about the C-N bonds or nitrogen inversion due protonation N-alkylation, revealed circular dichroism spectra, computational modelling X-ray diffraction analysis. flexible natures trianglamine macrocycles...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTConformational enantiomerism in bilirubin. Selection by cyclodextrinsDavid A. Lightner, Jacek K. Gawronski, and Krystyna GawronskaCite this: J. Am. Chem. Soc. 1985, 107, 8, 2456–2461Publication Date (Print):April 1, 1985Publication History Published online1 May 2002Published inissue 1 April 1985https://pubs.acs.org/doi/10.1021/ja00294a042https://doi.org/10.1021/ja00294a042research-articleACS PublicationsRequest reuse permissionsArticle...

More than a protecting group: The trityl group senses the chirality of an alkyl substituent in chiral ethers. CD spectra trityl-protected alcohols are highly sensitive to alcohol. use sensor provides new insight into structure and mode action molecular bevel gears shows relation between absolute configurations molecules their Cotton effect patterns.

Abstract Rapid progress in asymmetric synthesis stimulated a further development of methods and techniques for the determination absolute configuration chiral molecules. In recent years direct methods, i.e. X‐ray diffraction analysis, circular dichroism (vibrational electronic), Raman optical activity, rotation measurements, as well indirect relative assignment with use NMR spectroscopy or enzymatic transformations, are receiving increasing attention not only by specialists field but also...

Ab initio calculations of the optical rotation (OR) and electronic circular dichroism (ECD) for a series trans-diastereomers natural cytokine modulator cytoxazone 1−4 have been performed by density functional theory (DFT). The calculation OR ECD curves provides, after critical assessment, reliable method assignment absolute configuration these conformationally flexible molecules. effects level used calculations, changes conformer equilibrium, solvent influence on geometry values calculated...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA CD method for determination of the absolute stereochemistry acyclic glycols. 1. Application exciton chirality to 1,3-dibenzoate systemsNobuyuki Harada, Akira Saito, Hiroshi Ono, Jacek Gawronski, Krystyna Gawronska, Tatsuo Sugioka, Hisashi Uda, and Takeo KurikiCite this: J. Am. Chem. Soc. 1991, 113, 10, 3842–3850Publication Date (Print):May 1, 1991Publication History Published online1 May 2002Published inissue 1...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic structure of symmetric homoconjugated dienes. Circular dichroism (1S)-2-deuterio- and 2-methylnorbornadiene 2-methylbicyclo[2.2.2]octadieneDavid A. Lightner, Jacek K. Gawronski, Thomas D. BoumanCite this: J. Am. Chem. Soc. 1980, 102, 18, 5749–5754Publication Date (Print):August 1, 1980Publication History Published online1 May 2002Published inissue 1 August...

Chiral hexamine macrocycle derived from trans-1,2-diaminocyclohexane (DACH) in a complex with diethylzinc efficiently catalyzes the asymmetric hydrosilylation of N-phosphorylated aryl-alkyl or aryl-aryl ketimines protic media enantiomeric excess product approaching 100%. The cyclic structure trianglamine ligand increases enantioselectivity and/or yield reaction, comparison to catalysis by acyclic N,N′-dibenzyl-DACH ligands. Density functional theory (DFT) computations on model ligand-zinc...

Con-figured out: The tert-butyl group can be formally seen as "less" sterically demanding (M) than the methyl (L). This is case when a CD-active trityl at nitrogen atom used to report chirality of carbon substituent with two different sized groups (see scheme). use CD sensor allowed, in addition, determination dominant absolute configuration chiral amines.

The electronically excited states of the phthalimide chromophore have been studied by means linear dichroism (LD) samples partially oriented in poly(vinyl alcohol) films, magnetic circular (MCD), and (CD) spectroscopy. On basis LD measurements, low-energy tail (340−320 nm) first absorption band is assigned to an out-of-plane polarized n→π* transition (I). At higher energy, electronic spectrum resolved into contributions from five π→π* transitions: II (300 nm, long-axis polarized), III (275...

Chiral hexaazamacrocycles with a trianglamine structure and C3-symmetry, containing six ring substituents twelve stereocenters have been tested as chiral solvating agents (CSAs) for α-substituted carboxylic acids. Excellent results obtained hexaphenyl-substituted macrocycle. The optimal ratio between the macrocycle racemic acid, allowing baseline separation of enantiomers' signals in 1H NMR spectrum, was dependent on type particular its degree acidity. analyte CSA could be separated...