The First Enantioselective Syntheses of Axially Chiral Enantiomerically Pure Calix[4]resorcinarene Derivatives

1999 ◽  
Vol 121 (28) ◽  
pp. 6751-6752 ◽  
Author(s):  
Philip C. Bulman Page ◽  
Harry Heaney ◽  
Edward P. Sampler
Keyword(s):  
Enantiomerically Pure ◽  
Axially Chiral ◽  
Enantioselective Syntheses

Enantiomerically pure 1-(2-methoxy-1-naphthyl) and 1-(2-methylthio-1-naphthyl)isoquinoline: two new axially chiral NO and NS ligands for asymmetric catalysis

1999 ◽  
Vol 40 (3) ◽  
pp. 553-556 ◽  
Author(s):  
Giorgio Chelucci ◽  
Alessia Bacchi ◽  
Davide Fabbri ◽  
Antonio Saba ◽  
Fausta Ulgheri
Keyword(s):  
Asymmetric Catalysis ◽  
Enantiomerically Pure ◽  
Axially Chiral

Catalytic Atroposelective Dynamic Kinetic Resolution of Substituted Indoles

Synlett ◽  
2021 ◽  
Author(s):  
Ahreum Kim ◽  
Yongseok Kwon
Keyword(s):  
Asymmetric Catalysis ◽  
Kinetic Resolution ◽  
Ortho Position ◽  
Dynamic Kinetic Resolution ◽  
Research Attention ◽  
Considerable Research ◽  
Chiral Phosphoric Acid ◽  
Axially Chiral ◽  
High Yields ◽  
Enantioselective Syntheses

Advances in asymmetric catalysis have led to enormous progress in the atroposelective synthesis of axially chiral biaryls. Because of the biological importance of indoles, stereogenic axes in aryl-substituted indoles have attracted considerable research attention in recent years. Here we present a summary of recent advances in the atroposelective synthesis of aryl-substituted indoles by dynamic kinetic resolution. While several researchers have developed enantioselective syntheses of 3-arylindoles, N-arylindoles have been much less studied. Accordingly, we have reported a Pictet–Spengler reaction with catalytic and enantioselective control of the axial chirality around the C−N bond of the product. A chiral phosphoric acid induces the cyclization smoothly and with high yields and excellent enantioselectivities. To achieve this high selectivity, an NH group at the ortho position of the N-substituted aromatic ring that interacts favorably with the catalyst is required. Furthermore, when substituted aldehydes are used instead of paraformaldehyde, both the point and axial chiralities can be controlled during the cyclization.

scholarly journals Homochiral BINOL-based macrocycles with π-electron-rich, electron-withdrawing or extended spacing units as receptors for C60

2014 ◽  
Vol 10 ◽  
pp. 1308-1316 ◽  
Author(s):  
Marco Caricato ◽  
Silvia Díez González ◽  
Idoia Arandia Ariño ◽  
Dario Pasini
Keyword(s):  
Dicarboxylic Acids ◽  
Spectroscopic Methods ◽  
Statistical Distributions ◽  
One Pot ◽  
Enantiomerically Pure ◽  
One Pot Synthesis ◽  
Axially Chiral ◽  
Aromatic Dicarboxylic Acids ◽  
The One ◽  
Cyclic Adducts

The “one-pot” synthesis of several homochiral macrocycles has been achieved by using π-electron-rich, electron-deficient or extended aromatic dicarboxylic acids in combination with an axially-chiral dibenzylic alcohol, derived from enantiomerically-pure BINOL. Two series of cyclic adducts with average molecular D 2 and D 3 molecular symmetries, respectively, have been isolated in pure forms. Their yields and selectivities deviate substantially from statistical distributions. NMR and CD spectroscopic methods are efficient and functional in order to highlight the variability of shapes of the covalent macrocyclic frameworks. The larger D 3 cyclic adducts exhibit recognition properties towards C60 in toluene solutions (up to log K a = 3.2) with variable stoichiometries and variable intensities of the charge-tranfer band upon complexation.

scholarly journals Unexpected Racemization in the Course of the Acetalization of (+)-(S)-5-Methyl-Wieland–Miescher Ketone with 1,2-Ethanediol and TsOH under Classical Experimental Conditions

2019 ◽  
Vol 20 (24) ◽  
pp. 6147
Author(s):  
Francesca Leonelli ◽  
Irene Piergentili ◽  
Giulio Lucarelli ◽  
Luisa Maria Migneco ◽  
Rinaldo Marini Bettolo
Keyword(s):  
Natural Products ◽  
Experimental Conditions ◽  
Enantiomerically Pure ◽  
Bioactive Natural Products ◽  
Classical Procedure ◽  
Enantioselective Syntheses

(+)-(S) and (−)-(R)-5-methyl-Wieland-Miescher ketone (+)-1 and (−)-1, are important synthons in the diastereo and enantioselective syntheses of biological and/or pharmacological interesting compounds. A key step in these syntheses is the chemoselective C(1)O acetalization to (+)-5 and (−)-5, respectively. Various procedures for this transformation have been described in the literature. Among them, the classical procedure based on the use of 1,2-ethanediol and TsOH in refluxing benzene in the presence of a Dean-Stark apparatus. Within our work on bioactive natural products, it occurred to us to observe the partial racemization of (+)-5 in the course of the acetalization of (+)-1 by means of the latter methodology. Aiming to investigate this drawback, which, to our best knowledge, has no precedents in the literature, we acetalized with 1,2-ethanediol and TsOH in refluxing benzene and in the presence of a Dean–Stark apparatus under various experimental conditions, enantiomerically pure (+)-1. It was found that the extent of racemization depends on the TsOH/(+)-1 and 1,2-ethanediol/(+)-1 ratios. Mechanism hypotheses for this partial and unexpected racemization are provided.

Axially chiral 1,1′-binaphthyls with non-identical groups in 2,2′-positions. Synthesis of the enantiomerically pure 2-hydroxy-2′-thiol and substituted 2-amino-2′-thiols

1997 ◽  
Vol 8 (4) ◽  
pp. 537-546 ◽  
Author(s):  
Martin Smrčina ◽  
Štěpán Vyskočil ◽  
Jana Polívková ◽  
Jana Poláková ◽  
Jan Sejbal ◽  
...  
Keyword(s):  
Enantiomerically Pure ◽  
Axially Chiral
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