- Optical resolution of racemic stilbenediamine using N*-chiral ortho-palladated matrix
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Optical resolution of racemic stilbenediamine (Stien) was performed by recrystallization of its diastereomeric adducts with ortho-palladated (S)-N-isopropyl-α-methylbenzylamine. The less soluble (SCRN,SS) diasteteomer was studied by X-ray diffraction analysis. It was established that the crystal of this diastereomer consists of dimers formed via association of two molecules of the mononuclear cationic complex with an additional molecule of free diamine of the same absolute configuration. The association occurs through a system of hydrogen bonds and weak agostic interactions. Based on the X-ray diffraction data, the procedure was improved for the resolution of stilbenediamine due to the more profitable use of the ortho-palladated reagent. The Stien/Pd ratio in the diastereomer isolated was increased up to 3 : 2. The conformational features of the complex are discussed on the basis of 1H NMR spectroscopy data.
- Dunina,Kuz'mina,Parfyonov,Griskin
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Read Online
- Stereospecific co-crystallization of reactant and palladium complex in the resolution of stilbendiamine using N*-chiral ortho-palladated matrix
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Resolution of racemic 1,2-diphenyl-1,2-ethanediamine was performed through recrystallization of its diastereomeric adducts 2a,b with N*-chiral ortho-palladated complex (S(C)R(N))-1. The structure and absolute configuration of the less soluble (S(C)R(N),SS)-2a diastereomer was determined by X-ray diffraction. The complex has an unusual dimeric structure with a palladacycle:diamine ratio of 2:3; the association of 2a with an additional diamine molecule of the same (SS) absolute configuration is achieved due to hydrogen bonds between the coordinated and solvate diamine.
- Dunina,Kuz'mina,Parfyonov,Grishin
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Read Online
- Improved Optical Resolution of (+/-)-1,2-Diphenylethylenediamine
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(+/-)-1,2-Diphenylethylenediamine (DPEDA) was efficiently resolved by the fractional crystallization of its diastereomeric salts with optically active mandelic acid. 1H-NMR spectrum of N-monoacylated DPEDA with an optically active derivatizing agent showed that DPEDA thus obtained was optically pure.
- Saigo, Kazuhiko,Kubota, Naomi,Takebayashi, Shoko,Hasegawa, Masaki
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Read Online
- Asymmetric synthesis X IV: TiCl(Oipr)3 - promoted asymmetric coupling reaction of d-camphor ketimine anion
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Optically active 1,2-Diphenylethylenediamine (9) is obtained by asymmetric oxidative coupling reaction of d-camphor ketimine anion (4). Among various oxidating agents, TiCl(Oipr)3 is better than I2, Br2, CuCl2, FeCl3 and BrCH2CH2Br.
- Yaozhong,Wenhao,Jingen,Giulan
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Read Online
- Mechanistic studies inform design of improved Ti(salen) catalysts for enantioselective [3 + 2] cycloaddition
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Ti(salen) complexes catalyze the asymmetric [3 + 2] cycloaddition of cyclopropyl ketones with alkenes. While high enantioselectivities are achieved with electron-rich alkenes, electron-deficient alkenes are less selective. Herein, we describe mechanistic studies to understand the origins of catalyst and substrate trends in an effort to identify a more general catalyst. Density functional theory (DFT) calculations of the selectivity determining transition state revealed the origin of stereochemical control to be catalyst distortion, which is largely influenced by the chiral backbone and adamantyl groups on the salicylaldehyde moieties. While substitution of the adamantyl groups was detrimental to the enantioselectivity, mechanistic information guided the development of a set of eight new Ti(salen) catalysts with modified diamine backbones. These catalysts were evaluated with four electron-deficient alkenes to develop a three-parameter statistical model relating enantioselectivity to physical organic parameters. This statistical model is capable of quantitative prediction of enantioselectivity with structurally diverse alkenes. These mechanistic insights assisted the discovery of a new Ti(salen) catalyst, which substantially expanded the reaction scope and significantly improved the enantioselectivity of synthetically interesting building blocks.
- Robinson, Sophia G.,Wu, Xiangyu,Jiang, Binyang,Sigman, Matthew S.,Lin, Song
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p. 18471 - 18482
(2020/11/17)
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- Diboron glycol ester as well as preparation method, intermediate and application thereof
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The invention discloses diboron glycol ester as well as a preparation method, an intermediate and application thereof. The diboron glycol ester can be used for inducing reductive coupling reaction with imine as a substrate, and the substrate can be obtained by reaction of aldehyde and ammonia and is very easy to obtain and quite low in cost. The product can be separated from a reaction system onlyby acid-base operation without column chromatography purification, and the post-treatment mode is convenient and easy to operate. The yield of the obtained product is high, and protective group operation is not needed. The diboron glycol ester has chirality, the stereoselectivity of the reductive coupling reaction is generally excellent, and 99% ee chiral diamine can be obtained only through simple recrystallization. The diboron glycol ester can be obtained by reacting diol with diboron glycol ester, the diol is convenient to prepare and easy to amplify, the diol can be recycled from a reaction solution through simple acid-base operation, the recovery rate reaches 95%, and the preparation cost is further saved.
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Paragraph 0248-0252
(2020/08/02)
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- Enantioselective Reductive Coupling of Imines Templated by Chiral Diboron
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We herein report a general, practical, and highly efficient method for asymmetric synthesis of a wide range of chiral vicinal diamines via reductive coupling of imines templated by chiral diboron. The protocol features high enantioselectivity and stereospecificity, mild reaction conditions, simple operating procedures, use of readily available starting materials, and a broad substrate scope. The method signifies the generality of diboron-enabled [3,3]-sigmatropic rearrangement.
- Chen, Dongping,Li, Kaidi,Tang, Wenjun,Xu, Guangqing,Xu, Ronghua,Zhou, Mingkang
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supporting information
p. 10337 - 10342
(2020/07/04)
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- A New, Short, and Stereocontrolled Synthesis of C2-Symmetric 1,2-Diamines
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The previously unknown 5-spirocyclohexylisoimidazole has been made efficiently and simply by reaction of ammonia, glyoxal hydrate, and cyclohexanone. It is a very useful precursor for the diastereocontrolled synthesis of many C2-symmetric 1,2-diamines, a class which is important for the generation of a variety of C2-symmetric reagents and catalysts for enantioselective synthesis.
- Vemula, Rajender,Wilde, Nathan C.,Goreti, Rajendar,Corey
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p. 3883 - 3886
(2017/07/26)
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- Synergistic copper-TEMPO catalysis of intermolecular vicinal diamination of styrenes
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A copper-catalyzed, 2,2,6,6-tetramethyl piperidine N-oxy radical-assisted intermolecular diamination of styrenes with N-fluorobenzenesulfonimide has been developed. The current protocol proved amenable to a diverse array of styrenes via cascade radical addition to readily afford synthetically useful aromatic vicinal diamines with exclusive diastereoselectivity.
- Weng, Shiue-Shien,Hsieh, Kun-Yi,Zeng, Zih-Jian,Zhang, Jia-Wei
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p. 670 - 673
(2017/01/25)
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- Enantio- and Diastereoselective Nitro-Mannich Reaction of α-Aryl Nitromethanes with Amidosulfones Catalyzed by Phase-Transfer Catalysts
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A high-yield, highly diastereo- and enantioselective nitro-Mannich reaction of α-aryl nitromethanes with amidosulfones catalyzed by a novel chiral phase-transfer catalyst, bearing multiple H-bonding donors, derived from quinine was developed. A variety of α-aryl nitromethanes and amidosulfones were investigated; and the corresponding products were obtained in excellent yields with excellent diastereo- and enantioselectivities (up to 99% yield, > 99:1 dr and >99% ee). As a demonstration of synthetic utility, the resulting β-nitroamines could be converted to corresponding meso-symmetric and optically pure unsymmetric anti-1,2-diarylethylenediamines.
- Lu, Ning,Li, Ruxu,Wei, Zhonglin,Cao, Jungang,Liang, Dapeng,Lin, Yingjie,Duan, Haifeng
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p. 4668 - 4676
(2017/05/12)
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- Direct catalytic asymmetric mannich-type reaction of benzyl isocyanide: Stereoselective synthesis of 1,2-diarylethylenediamines
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A direct catalytic asymmetric Mannich-type reaction of benzyl isocyanide using a CuI catalyst and N-(diphenylthiophosphinoyl)imines was developed. The simultaneous activation strategy by soft-soft interaction was the key to promote the reaction using a weakly acidic pronucleophile, benzyl isocyanide. The spontaneous cyclization of the Mannich adduct afforded the corresponding enantioenriched imidazolines, which could be precursors for a variety of 1,2-diarylethylenediamines. Enantioenriched 4,5-diarylimidazolines were directly accessed by catalytic asymmetric C-C bond-forming reaction of benzyl isocyanide and N-(thiophosphinoyl)aldimines. The imidazolines were readily transformed into enantioenriched 1,2-diarylethylenediamines.
- Tamura, Keiji,Kumagai, Naoya,Shibasaki, Masakatsu
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supporting information
p. 3026 - 3031
(2015/05/13)
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- Lipase-catalyzed desymmetrization of meso-1,2-diaryl-1,2-diaminoethanes
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The synthesis and enzyme-catalyzed desymmetrization of meso-1,2-diaryl-1,2- diaminoethanes have been investigated. A family of aromatic meso-1,2-diamines, containing different substitution patterns in the aromatic ring, was first prepared and then desymmetrized enantioselectively using lipases as biocatalysts. Selective alkoxycarbonylation of one of the amino groups was achieved using allyl carbonates, isolating the corresponding allyl monocarbamates with moderate to high enantiomeric excess at 45 C. Candida antarctica lipase types A (CAL-A) and B (CAL-B) displayed the best activities and stereopreferences, with a dramatic influence being observed depending on the diamine structure. Non substituted and para-substituted aryldiamines led to the formation of allyl carbamates with good enantiomeric excess, using CAL-A for the less hindered substrates and CAL-B for the more hindered ones. On the other hand meta- and ortho-derivatives afforded low or negligible conversions and selectivities, respectively.
- Mendez-Sanchez, Daniel,Rios-Lombardia, Nicolas,Garcia-Granda, Santiago,Montejo-Bernardo, Jose,Fernandez-Gonzalez, Alfonso,Gotor, Vicente,Gotor-Fernandez, Vicente
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p. 381 - 386
(2014/04/03)
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- Enantioseparation of 1-arylethanols via a supramolecular chiral host consisting of N-(2-naphthoyl)-l-aspartic acid and an achiral diamine
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A supramolecular chiral host consisting of N-(2-naphthoyl)-l-aspartic acid (L-1) and meso-1,2-diphenylethylenediamine (2) is effective in enantioseparation of 1-arylethanols (up to 96% ee with 100% inclusion ratio). Here we report three different methods to prepare the inclusion crystals and discuss the chiral recognition mechanism on the basis of X-ray crystallography results.
- Kodama, Koichi,Kanno, Ayaka,Sekine, Eriko,Hirose, Takuji
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experimental part
p. 1877 - 1882
(2012/04/23)
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- A synthesis of the pseudopterosin A-F aglycone
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The synthesis of the pseudopterosin A-F aglycone from 3-methylcatechol features (a) the use of asymmetric Ireland-Claisen and aryl Claisen rearrangements to install three of the four stereocentres present in the molecule and (b) an A→AB→ABC annulation strategy using ring-closing metathesis and cationic cyclisation reactions as the key steps.
- Cooksey, John P.,Kocienski, Philip J.,Schmidt, Arndt W.,Snaddon, Thomas N.,Kilner, Colin A.
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supporting information
p. 2779 - 2785,7
(2020/07/31)
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- Synthesis, characterization and antimicrobial activity of novel platinum(IV) and palladium(II) complexes with meso-1,2-diphenyl-ethylenediamine- N,N'-di-3-propanoic acid - Crystal structure of H2-1,2- dpheddp·2HCl·H2O
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In the reaction of meso-1,2-diphenyl-ethylenediamine (1,2-dphen) with neutralized 3-chlor-propanoic acid, the new linear tetradentate edda-like ligand (edda = ethylenediamine-N,N'-diacetic ion) meso-1,2-diphenyl-ethylenediamine-N, N'-di-3-propanoic acid d
- Radi?, Gordana P.,Glodovi?, Verica V.,Ratkovi?, Zoran R.,Novakovi?, Sladana B.,Garcia-Granda, Santiago,Roces, Laura,Menéndez-Taboada, Laura,Radojevi?, Ivana D.,Stefanovi?, Olgica D.,?omi?, Ljiljana R.,Trifunovi?, Sre?ko R.
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p. 180 - 186
(2013/01/15)
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- Design, synthesis, and biological evaluation of imidazoline derivatives as p53-MDM2 binding inhibitors
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Three series of novel imidazoline derivatives were designed, synthesized, and evaluated for their p53-MDM2 binding inhibitory activities, and anti-proliferation activities against PC3, A549, KB, and HCT116 cancer cell lines. Five of the tested compounds showed enhanced p53-MDM2 binding inhibitory potency and anti-proliferation activities in comparison with that of Nutlin-1. Flow cytometric analysis indicated that compound 7c, one of the most potent p53-MDM2 binding inhibitors with a Ki value of 0.6 μM, showed its ability to arrest cell cycle progression.
- Hu, Chunqi,Li, Xin,Wang, Weisi,Zhang, Lei,Tao, Lulu,Dong, Xiaowu,Sheng, Rong,Yang, Bo,Hu, Yongzhou
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p. 5454 - 5461
(2011/10/30)
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- COMPOSITIONS AND METHODS FOR CYCLOFRUCTANS AS SEPARATION AGENTS
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The present invention relates to derivatized cyclofructan compounds, compositions comprising derivatized cyclofructan compounds, and methods of using compositions comprising derivatized cyclofructan compounds for chromatographic separations of chemical species, including enantiomers. Said compositions may comprise a solid support and/or polymers comprising derivatized cyclofructan compounds.
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Page/Page column 45-49; 62
(2010/12/31)
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- Optical monitoring of gases with cholesteric liquid crystals
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A new approach to optical monitors for gases is introduced using cholesteric liquid crystals doped with reactive chiral compounds. The approach is based on cholesteric pitch length changes caused by a change in helical twisting power (HTP) of the chiral dopants upon reaction with the analyte. The concept is demonstrated for monitoring carbon dioxide via reversible carbamate formation and for oxygen using the irreversible oxidation of a chiral dithiol to a disulfide. Monitoring of CO2 was achieved by doping a commercial cholesteric liquid crystalline mixture (E7) with 1.6% mol of the 1:1 complex of an optically pure diamine with a TADDOL derivative. Upon exposure to carbon dioxide, the reflection band of a thin film of the mixture shifted from 637 to 495 nm as a consequence of dissociation of the complex after carbamate formation of the diamine. An O2 monitor was obtained by doping E7 with a chiral binaphthyl dithiol derivative and a nonresponsive codopant. The reflection band of the oxygen monitor film changed from 542 to 600 nm, due to the conformational change accompanying oxidation of the dithiol to disulfide. These monitoring mechanisms hold promise for application In smart packaging, where carbon dioxide and oxygen are of special interest because of their roles in food preservation.
- Han, Yang,Pacheco, Katherine,Bastiaansen, Cees W.M.,Broer, Dirk J.,Sijbesma, Rint P.
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body text
p. 2961 - 2967
(2010/05/01)
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- Chiral recognition based on enantioselectively aggregation-induced emission
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(Figure Presented) Novel chiral AIE compounds bearing a tartaric acid group were synthesized. They selectively aggregated with one enantiomer of a number of chiral amines, such that one enantiomer led to strong fluorescence and another enantiomer showed no or only weak fluorescence. This was used for the quantitative analysis of enantiomeric composition.
- Zheng, Yan-Song,Hu, Yu-Jian
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scheme or table
p. 5660 - 5663
(2009/12/26)
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- Homogeneous asymmetric hydrogenation catalyst
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Provide that a useful catalyst for homogeneous hydrogenation, particularly a catalyst for homogeneous asymmetric hydrogenation for hydrogenation, particularly asymmetric hydrogenation, which is obtainable with comparative ease and is excellent in economically and workability, and a process for producing a hydrogenated compound of an unsaturated compound, particularly an optically active compound using said catalyst with a high yield and optical purity.
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- A convenient preparation of enantiomerically pure (+)-(1R,2R)- and (-)-(1S,2S)-1,2-diamino-1,2-diphenylethanes
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A gram-scale preparation of (1S,2S)- and (1R,2R)-1,2-diamino-1,2- diphenylethanes, (1S,2S)-1 and (1R,2R)-1, is reported via (±)-iso-amarine 4. Strategically, the activation of (±)-iso-amarine 4 for hydrolysis to the required diamines and enantiomeric resolution is achieved simultaneously by formation of two separable diastereoisomeric N-acylamidines 5 and 6 derived from direct DCC-mediated coupling of (±)-iso-amarine 4 with (R)-acetylmandelic acid. iso-Amarine 4 is conveniently obtained from amarine 3, and a one-pot synthesis of the latter is reported from benzaldehyde and hexamethyldisilazane as catalysed by benzoic acid.
- Braddock, D. Christopher,Redmond, Joanna M.,Hermitage, Stephen A.,White, Andrew J. P.
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p. 911 - 916
(2007/10/03)
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- Fractional crystallisation of (±)-iso-amarine with mandelic acid: convenient access to (R,R)- and (S,S)-1,2-diamino-1,2-diphenylethanes
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(±)-iso-Amarine can be conveniently resolved via 1:1 salt formation with either hand of mandelic acid. Enantiopure iso-amarine can be acetylated and hydrolysed to give enantiopure 1,2-diamino-1,2-diphenylethanes.
- Braddock, D. Christopher,Hermitage, Stephen A.,Redmond, Joanna M.,White, Andrew J.P.
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p. 2935 - 2937
(2007/10/03)
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- Reductive coupling of aromatic oxims and azines to 1,2-diamines using Zn-MsOH or Zn-TiCl4
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The reduction of aromatic aldoxims and azines with Zn in the presence of MsOH or TiCl4 afforded N,N′-unsubstituted 1,2-diamines in one-step. The reductive coupling with Zn-MsOH gave meso 1,2-diamines selectively, whereas dl 1,2-diamines were fo
- Kise, Naoki,Ueda, Nasuo
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p. 2365 - 2368
(2007/10/03)
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- A simplified synthesis of (±)-1,2-Diphenyl-1,2-diaminoethane (1) from benzaldehyde and ammonia. Revision of the structures of the long-known intermediates 'hydrobenzamide' and 'amarine'
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A new pathway for the simple, stereocontrolled and economical synthesis of (±)-1 from benzaldehyde is described. The structures of two intermediates (Scheme 1) have been revised to those shown in Scheme 2.
- Corey,Kuehnle, Florian N. M.
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p. 8631 - 8634
(2007/10/03)
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- Organic chemistry: Preparative synthesis of the Corey chiral controller for enantioselective dihydroxylation of olefins
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A five-step synthesis of both enantiomers of 1,2-di(2,4,6-trimethylbenzylamino)-1,2-diphenylethane, i.e., Corey (R,R)- and (S,S)-controllers for enantioselective dihydroxylation of olefins by osmium tetroxide, starting from α,α'-diphenylglyoxime, has been developed. The key operations in the synthesis are the optical resolution of intermediate rac-1,2-diamino-1,2-diphenylethane into two enantiomers using only (R,R)-tartaric acid and the subsequent enhancement of the enantiomeric purity to >98% by crystallizations of the corresponding Schiff's bis-bases. Analysis of the enantiomeric purity of the controllers can be easily performed using 1H NMR spectra of their salts with (R)-α-methoxy-α-(trifluoromethyl)phenylacetic acid (Mosher R-acid).
- Lapitskaya,Pivnitsky
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- Convenient Routes to Symmetrical Benzils and Chiral 1,2-Diaryl-1,2-diaminoethanes, Useful Controllers and Probes for Enantioselective Synthesis
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Pathways for the diastereoselective preparation of chiral 1,2-diaryl-1,2-diaminoethanes from ArCOOH, ArCHO or ArBr are described.
- Corey, E. J.,Lee, Duck-Hyung,Sarshar, Sepehr
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- Synthesis of Nitrogen-Containing Macrocycles with Reductive Intramolecular Coupling of Aromatic Diimines
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Reductive intramolecular coupling of aromatic diimines is an effective method for the synthesis of a variety of nitrogen-containing macrocycles. 1,4-Diazacrown ethers 3 were effectively synthesized by intramolecular coupling of bis(imino ethers) 9 promoted by electroreduction (method A) or chemical reduction with zinc powder (method B) in the presence of methanesulfonic acid.In spite of the formation of macrocycles, the yields of 3 were relatively high.This can be explained by the formation of proton-bridged intermediates 14, in which intramolecular hydrogen bonds are formed between hydrogen and oxygen atoms of diiminium salts.Method B was more effective in the formation of 1,4-diaza-12-crown-4 derivatives 3 (n = 1) due to the template effect of Zn(2+).Optically active macrocyclic bislactones 4 were synthesized stereoselectively by reductive intramolecular coupling of bis(imino esters) 20 with zinc powder (method B).The high stereoselectivity is explained by considering proton-bridged intermediate 23.The resultant compounds 4 were transformed to optically active 1,2-diarylethylenediamines 7.Various sizes of macrocyclic bislactams 5 were synthesized by reductive intramolecular coupling of bis(imino amides) 26 with zinc powder (method B).Reduction of 5 gave the corresponding macrocyclic polyamines 6.
- Kise, Naoki,Oike, Hideaki,Okazaki, Eiichi,Yoshimoto, Masami,Shono, Tatsuya
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p. 3980 - 3992
(2007/10/02)
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- Stereochemical Studies of N,N'-Diacetyl-N,N'-dimethyl-1,2-diamino-1,2-diphenylethanes and their Mono- and Di-thio Analogues by NMR and CD Spectroscopy and by Molecular Mechanics Calculations
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The R*,R* and R*,S* diastereomers of N,N'-diacetyl-N,N'dimethyl-1,2-diamino-1,2-diphenylethane and their mono- and di-thio analogues (1-6) have been studied by 1H and 13C NMR spectroscopy and by empirical force-field calculations (MMP2-85).The NMR spectral data (chemical shifts, coupling constants and NOE) clearly show that all compounds exist in the anti conformation with the Z,Z configuration for the (thio)amide groups.The same result is obtained by the force-field calculations.Four of the compounds (2, 3, 4 and 6) are chiral and have been resolved into enantiomers by chromatography on triacetylcellulose.The CD spectra of the first eluted enantiomers of 4 and 6 could be reasonably well reproduced by calculations based on minimum energy geometries for the S,S enantiomers, whereas no agreement could be reached for 2 and 3.This agrees with the results of the force-field calculations, which predict one predominant conformer for each of 4 and 6, but significant amounts of two rotamers (both anti ZZ) for each of 2 and 3.
- Chiara, Jose Luis,Petrova, Rumyana,Simeonov, Mario,Spassov, Stefan L.,Khan, Agha Zul-Quarnain,Sandstroem, Jan
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p. 555 - 562
(2007/10/02)
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- Synthesis of Homochiral Amino Alcohols, Aziridines and Diamines via Homochiral Cyclic Sulphites
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Vicinal diols react with thionyl chloride to give 1,2-cyclic sulphites in quantitative yield, which undergo facile ring opening by lithium azide in dimethylformamide to yield azido alcohols and the latter in turn have been stereoselectively transformed into amino alcohols, aziridines and diamines.
- Lohray, Braj B.,Ahuja, Jaimala R.
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- An efficient and practical route to enantiomerically pure (+)-(1R,2R)- and (-)-(1S,2S)-1,2-diphenylethane-1,2-diamines
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The synthesis of the title compounds is easily achieved by the asymmetric Sharpless dihydroxylation of trans-stilbene to the corresponding enantiomerically pure diols. The conversion of the diols to the di-p-toluenesulfonates and subsequent reaction with sodium azide affords the diazides, which are reduced by lithium aluminum hydride to the optically pure 1,2-diamines.
- Pini,Iuliano,Rosini,Salvadori
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p. 1023 - 1024
(2007/10/02)
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- 208. Aminierende reduktive Kupplung aromatischer Aldehyde mit niedervalenten Titan-Reagenzien zu 1,2-Diarylethylendiaminen
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In a novel McMurry-type one-pot reaction, aromatic aldehydes and secondary amines are coupled to give the N,N,N',N'-tetralkyl-1,2-diarylethylendiamines 1-22 (Table 3).To this end, a lithium dialkylamide is added to an aromatic aldehyde to give the adduct B which is then treated with 1 equiv. of TiCl4 to yield a coloured suspension of a reagent synthetically equivalent to a iminium salt (C/D in Scheme 4).After treatment with a low-valent Ti reagent which is prepared by reduction of TiCl4 with either K or, preferably, Mg, the coupling products are isolated in 23 to 81 percent yield as a 1:1 mixture of the diastereoisomers (meso- and rac-form).These are separated either by chromatography or by crystallization and characterized.
- Betschart, Claudia,Seebach, Dieter
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p. 2215 - 2231
(2007/10/02)
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- ASYMMETRIC REDUCTION OF ACETOPHENONE WITH CHIRAL REAGENTS FROM LITHIUM TETRAHYDROALUMINATE AND CHIRAL 1,2-DIOL OR DIAMINE AS STUDIED BY ALUMINUM-27 NUCLEAR MAGNETIC RESONANCE
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Asymmetric reduction of acetophenone with chiral reagents from lithium tetrahydroaluminate and (1S,2S)-1,2-diphenylethanediol or (1S,2S)-N,N'-diethyl-1,2-diphenylethanediamine in the presence or absence of added ethanol is studied by aluminum-27 NMR spectroscopy.
- Yamashita, Junzo,Tomiyama, Shigemi,Hashimoto, Harukichi,Kitahara, Keiichi,Sato, Hisao
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p. 749 - 752
(2007/10/02)
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- Ueber die Enantiomerentrennung durch Verteilung zwischen fluessigen Phasen 3. Mitteilung. Selektivitaet der lipophilen Weinsaeureester fuer chirale Ammonium-Salze verschiedener Konstitution und Konfiguration
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Several methods are described which allow determination on a small scale of the enantiomer distribution constant Q, and the affinity coefficient P, which characterize the enantioselectivity and the affinity of a lipophilic phase for ammonium salts of different constitution and configuration.The influence of concentration of the tartaric acid ester, temperature, concentration and type of the lipophilic anion on Q and P was investigated to find out favourable experimental conditions for resolutions of racemates by iterative processes, e.g. partition chromatography.The relation ship between Q and the configuration of aminoalcohols 1-12 was explored and the observed regularities are pointed out.In addition it was found that lipophilic tartaric acid esters are enantioselective to salts of threo-1,2-diphenyl-1,2-ethanediamine 13, and to phenylglycine and its derivatives 14-16.
- Prelog, Vladimir,Mutak, Stjepan,Kovacevic, Krunoslav
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p. 2279 - 2284
(2007/10/02)
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- Thermal Rearrangements and Nucleophilic Ring Cleavage of cis-2,3-Dihydro-2,3-diphenyl-1H-1,4-diazepines
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Thermolysis of cis-2,3-dihydro-2,3-diphenyl-1H-1,4-diazepine (c2a) at 150 deg C in 5>bromobenzene solution affords quantitatively 2,3-diphenylpyridine (4a) via ring contraction and loss of one mole of ammonia.In striking contrast, on heating a 5>bromobenzene solution of cis-2,3-dihydro-2,3,6-triphenyl-1H-1,4-diazepine (c2b) to 140 deg C loss of C7H8 occurs resulting in the formation of 2,5-diphenylpyrimidine (5b) in 70percent yield.Mechanisms are proposed in order to rationalize these surprising ring contractions.Piperidine in methanol cleaved the ring of c2a*H+ producing meso-1,2-diphenyl-1,2-ethanediamine (12) and 1,3-dipiperidinopropenylium perchlorate (13).
- Quast, Helmut,Seidenspinner, Hubert-Matthias,Stawitz, Josef
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p. 1230 - 1236
(2007/10/02)
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