- Synthesis and characterization of novel chiral imidazolium and pyridinium ionic liquids derived from tartaric acid and 2-oxazolidinone
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Novel chiral imidazolium and pyridinium ionic liquids based on tartaric acid and 2-oxazolidinone were designed. Symmetrical dicationic ionic liquids based on tartaric acid have been synthesized and characterized. These chiral ionic liquids were designed b
- Nehate, Sagar P.,Godbole, Himanshu M.,Singh, Girij P.,Mathew, Jessy E.,Shenoy, Gautham G.
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- Synthesis and application of N-3,5-dinitrobenzoyl and C3 symmetric diastereomeric chiral stationary phases
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Three diastereomeric chiral compounds, namely, (R,R)-(+)-2-amino-1,2-diphenylethanol, (1S,2R)-(+)-2-amino-1,2-diphenylethanol, and (1R,2R)-(+)-1,2-diphenylethylenediamine were used as starting materials for preparing three N-3,5-dinitrobenzoyl derivative
- Ryoo, Jae Jeong,Yu, Jeong Jae
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- Stereoselective Visible-Light Catalyzed Cyclization of Bis(enones): A Viable Approach to the Synthesis of Enantiomerically Enriched Cyclopentane Rings
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Photoredox catalytic cyclization of aryl enones in the presence of visible light, promoted either by metals or organic dyes, represent a valuable strategy for the synthesis of cycloalkanes. The development of a stereoselective version of such transformation, in the presence of the metal-free catalyst Eosin Y was studied, with the aim to realize an efficient protocol for the in-flow synthesis of enantiomerically enriched functionalized cyclopentane rings, taking advantage of the flow reactors technology. The use of a chiral auxiliary on the bisenone to be cyclized offers a straightforward and convenient option to exert a stereocontrol on the light-driven cyclization. By exploiting Evans’ oxazolidinones, the stereoselective light-driven cyclization affords, after the removal of the chiral auxiliary, a functionalized 1,2-trans cyclopentane ring in up to 83/17 enantiomeric ratio. When the reaction was performed in continuo, in a homemade coil photoreactor, high yields were observed. The cyclization was also successfully realized in a 3D-printed mesoreactor, without any change in the diastereoseletctivity of the process.
- Medici, Fabrizio,Resta, Simonetta,Presenti, Piero,Caruso, Lucia,Puglisi, Alessandra,Raimondi, Laura,Rossi, Sergio,Benaglia, Maurizio
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supporting information
p. 4521 - 4524
(2021/06/12)
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- Synthesis of new C3 symmetric amino acid- and aminoalcohol-containing chiral stationary phases and application to HPLC enantioseparations
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We recently reported a new C3-symmetric (R)-phenylglycinol N-1,3,5-benzenetricarboxylic acid-derived chiral high-performance liquid chromatography (HPLC) stationary phase (CSP 1) that demonstrated better results as compared to a previously described N-3,5-dintrobenzoyl (DNB) (R)-phenylglycinol-derived CSP. Over a decade ago, (S)-leucinol, (R)-phenylglycine, and (S)-leucine derivatives were used as the starting materials of 3,5-DNB-based Pirkle-type CSPs for chiral separation. In this study, three new C3-symmetric CSPs (CSP 2, 3, and 4) were prepared by combining the ideas and results mentioned above. Here we describe the synthetic procedures and applications of the new C3-symmetric CSPs (CSP 2–CSP 4).
- Yu, Jeongjae,Armstrong, Daniel W.,Ryoo, Jae Jeong
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- PROCESSES FOR PREPARING 2-DIHALO RIBOLACTONES
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Methods for forming 2-bromo, 2-fluoro ribofuranose intermediates and 2-chloro, 2- fluoro ribofuranose intermediates for use in preparing antiviral nucleosides are disclosed. Methods for forming nucleosides, and nucleoside prodrugs, using the intermediates, are also disclosed. The methods all produce intermediates, and the resulting nucleosides and prodrugs thereof, wherein the chirality of the carbon at the 2-position is controlled. In some embodiments, the chemistry involves using chiral auxiliaries, such as (R)-2,2-dimethyl-l,3- dioxolane-4-carbaldehyde, and in other embodiments, the chemistry involves using chiral starting materials, such as D-xylose.
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Page/Page column 60
(2017/06/21)
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- Synthesis of (2S)-2-Chloro-2-fluororibolactone via Stereoselective Electrophilic Fluorination
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A novel and efficient route for the preparation of (2S)-2-chloro-2-fluorolactone 29 is described. This approach takes advantage of a highly efficient diastereoselective electrophilic fluorination reaction (94% yield; >50:1 dr)
- De Schutter, Coralie,Sari, Ozkan,Coats, Steven J.,Amblard, Franck,Schinazi, Raymond F.
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p. 13171 - 13178
(2017/12/26)
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- Asymmetric diastereoselective thia-hetero-Diels-Alder reactions of dithioesters
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Asymmetric thia-Diels-Alder reactions involving new dithioesters bearing a chiral auxiliary are described, with diastereoselectivities up to 78%. Double-stereodifferentiating experiments employing chiral substrates in the presence of a chiral Lewis acid c
- Dentel, Hélène,Chataigner, Isabelle,Lohier, Jean-Franois,Gulea, Mihaela
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supporting information; experimental part
p. 2326 - 2335
(2012/04/10)
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- Enantioselective total synthesis of (-)-Clavosolide A and B
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Enantioselective total synthesis of (-)-clavosolide A and B was reported in full including the synthesis of proposed structure of (-)-clavosoldie A (1), revised structure of (-)-clavosoldie A (5), and revised structure of (-)-clavosoldie B (6). The relative and absolute stereochemistries of the natural products were confirmed unambiguously by comparing the optical rotation values and 1H and 13C NMR spectra of them.
- Son, Jung Beom,Kim, Si Nae,Kim, Na Yeong,Hwang, Min-Ho,Lee, Wonsun,Lee, Duck Hyung
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scheme or table
p. 653 - 663
(2010/08/19)
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- Chiral Auxiliary-Bearing Isocyanides as Synthons: Synthesis of Strongly Fluorescent (+)-5-(3,4-Dimethoxyphenyl)-4-[[N-[(4S) -2-oxo-4- (phenylmethyl) -2-oxazolidinyl] ] carbonyl] oxazole and Its Enantiomer
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Both (4S-(+)-3-(isocyanoacetyl)-4-(phenylmethyl)-2-oxazolidinone (R)-1 and its enantiomer (S)-1 have been synthesized as potentially useful synthons in asymmetric synthesis. Optically active (+)-5-(3,4-dimethoxyphenyl)-4-[[N-[(4S)-2-oxo-4-(phenylmethyl)-2
- Tang, Jian S.,Verkade, John G.
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p. 8750 - 8754
(2007/10/03)
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- Asymmetric Glycine Enolate Aldol Reactions: Synthesis of Cyclosporine's Unusual Amino Acid, MeBmt
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The chiral glycine synthon, 3c, as its derived stannous enolate, has been demonstrated to undergo a highly syn diastereoselective aldol addition reaction with representative aldehydes to give the adducts 5 (R = C6H5, Me, Me2CH) in yields ranging from 71 to 92percent.The utility of these intermediates has been demonstrated via the subsequent three-step transformation of these adducts to the enantiomerically pure N-methyl β-hydroxy amino acids 1.This reaction methodology has been applied to the asymmetric synthesis of (4R)-4-((E)-2-butenyl)-4,N-dimethyl-L-threonine (1a), an important constituent in the immunosuppressant peptide cyclosporine.Several additional structural analogues of 1a were also prepared in conjunction with this study.
- Evans, David A.,Weber, Ann E.
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p. 6757 - 6761
(2007/10/02)
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