18531-99-2Relevant articles and documents
One-pot preparation of chiral dinuclear vanadium(V) complex
Takizawa, Shinobu,Rajesh, Doss,Katayama, Tomomi,Sasai, Hiroaki
, p. 1667 - 1669 (2009)
A convenient one-pot procedure for the preparation of dinuclear vanadium(V) complex is described. The complex exhibited high catalytic activity for oxidative coupling of 2-naphthol derivatives. In addition, coupling of 9-phenanthrol gave (S)-10,10′-dihydroxy-9,9′-biphenanthryl in quantitative yield with 93% ee. Georg Thieme Verlag Stuttgart.
Induction of Axial Dissymmetry into the 1,1'-Binaphthyl Bond via an Intramolecular Ullmann Coupling Reaction
Miyano, Sotaro,Tobita, Masayuki,Nawa, Masayoshi,Sato, Shinya,Hashimoto, Harukichi
, p. 1233 - 1234 (1980)
Intramolecular Ullmann coupling of (S)-2,2'-bis-(1-bromo-2-naphthylcarbonyloxy)-1,1'-binaphthyl induced axial dissymmetry of the S-configuration into the newly formed 1,1'-binaphthyl linkage affording (S,S)-tetranaphthodioxacyclododecene-11,16-dione with virtually complete diastereoselectivity.
Enantioselective, Electrocatalytic Oxidative Coupling of Naphthol, Naphthyl Ether and Phenanthrol on a TEMPO-modified Graphite Felt Electrode in the Presence of (-)-Sparteine (TEMPO = 2,2,6,6-tetramethylpiperidin-1-yloxyl)
Osa, Tetsuo,Kashiwagi, Yoshitomo,Yanagisawa, Yoshinori,Bobbitt, James M.
, p. 2535 - 2538 (1994)
Constant potential electrolysis of 2-naphthol, 2-methoxynaphthalene and 10-hydroxyphenanthrene at 0.6 V vs.Ag/AgCl on a TEMPO-modified graphite felt electrode in the presence of (-)-sparteine in acetonitrile yields, enantioselectively, (S)-binaphthyl type dimers in > 92percent isolated yield and with > 88percent current efficiency with enantiomeric excess of 98, 91 and 97percent respectively for each dimer, respectively.
A HIGHLY STEREOSELECTIVE SYNTHESIS OF S(-)--2,2'-DIOL.
Brussee, J.,Jansen, A.C.A.
, p. 3261 - 3262 (1983)
The title compound is synthesized from 2-naphthol by a S-(+)-amphetamine-copper (II) complex in high chemical yield ( 85percent ) and high optical purity ( up to 95percent ).
Thermal racemization of biaryl atropisomers
Patel, Darshan C.,Woods, Ross M.,Breitbach, Zachary S.,Berthod, Alain,Armstrong, Daniel W.
, p. 1557 - 1561 (2017)
Many biaryl compounds possess atropisomerism due to the steric hindrance of substituents at the ortho-position of the two aromatic moieties. Upon heating, atropisomers may have enough energy to surpass the rotational energy barrier and racemize. The thermal stability of five atropisomers was studied using chiral chromatography by following the change in enantiomeric excess ratio at different temperatures. The first order racemization reaction rate was obtained at a given temperature as the slope of the change in enantiomeric excess ratio versus time. For each atropisomer, the racemization rates at different temperatures led to the value of the rotational energy barrier for racemization, ΔG?, and to the racemization half lifetime, t1/2, indicating the atropisomer thermal stability. Binaphthol started to racemize significantly at temperature of 190 °C and above while binaphthyldiamine was much more stable showing little or very minor racemization up to 210 °C. A chloro-substituted phenylamino-naphthol was very sensitive to thermal racemization starting at a low 40 °C.
Practical method and novel mechanism for optical resolution of BINOL by molecular complexation with N-benzylcinchoninium chloride
Wang, Yang,Sun, Jie,Ding, Kuiling
, p. 4447 - 4451 (2000)
A highly efficient and practical resolution of racemic 1,1'-bi-2- naphthol (BINOL) has been achieved through molecular complexation with N- benzylcinchoninium chloride, which can be readily prepared in 85% yield using an improved procedure through the reaction of cinchonine with benzyl chloride in dimethylformamide (DMF). It is found that the absolute configuration of BINOL included in the molecular crystals is R, which is the same as in the case of using N-benzylcinchonidinium chloride. This result is discussed in terms of molecular recognition in the solid state. X-Ray structural analysis of molecular crystal formed between (R)-BINOL and N-benzylcinchoninium chloride indicates that the additive effect of the chiral features of the host, the interaction pattern between the functional groups of the host and guest, and the complementary molecular packing in the crystal lattice dominates the stereochemistry of the guest in the molecular crystal. (C) 2000 Elsevier Science Ltd.
Catalytic enantioselective synthesis of atropisomeric biaryls by a cation-directed O-alkylation
Jolliffe, John D.,Armstrong, Roly J.,Smith, Martin D.
, p. 558 - 562 (2017)
Axially chiral biaryls, as exemplified by 1,1′-bi-2-naphthol (BINOL), are key components of catalysts, natural products and medicines. These materials are synthesized conventionally in enantioenriched form through metal-mediated cross coupling, de novo construction of an aromatic ring, point-to-axial chirality transfer or an atropselective transformation of an existing biaryl. Here, we report a highly enantioselective organocatalytic method for the synthesis of atropisomeric biaryls by a cation-directed O-alkylation. Treatment of racemic 1-aryl-2-tetralones with a chiral quinidine-derived ammonium salt under basic conditions in the presence of an alkylating agent leads to atropselective O-alkylation with e.r. up to 98:2. Oxidation with DDQ gives access to C 2 -symmetric and non-symmetric BINOL derivatives without compromising e.r. We propose that the chiral ammonium counterion differentiates between rapidly equilibrating atropisomeric enolates, leading to highly atropselective O-alkylation. This dynamic kinetic resolution process offers a general approach to the synthesis of enantioenriched atropisomeric materials.
Chiral separation materials based on derivatives of 6-amino-6-deoxyamylose
Gao, Ya-Ya,Zhang, Yu-Hang,Zhang, Shan,Chen, Wei,Bai, Zheng-Wu
supporting information, p. 899 - 914 (2021/10/07)
In order to develop new type of chiral separation materials, in this study, 6-amino-6-deoxyamylose was used as chiral starting material with which 10 derivatives were synthesized. The amino group in 6-amino-6-deoxyamylose was selectively acylated and then the hydroxyl groups were carbamoylated yielding amylose 6-amido-6-deoxy-2,3-bis(phenylcarbamate)s, which were employed as chiral selectors (CSs) for chiral stationary phases of high-performance liquid chromatography. The resulted 6-amido-6-deoxyamyloses and amylose 6-amido-6-deoxy-2,3-bis(phenylcarbamate)s were characterized by IR, 1H NMR, and elemental analysis. Enantioseparation evaluations indicated that most of the CSs demonstrated a moderate chiral recognition capability. The 6-nonphenyl (6-nonPh) CS of amylose 6-cyclohexylformamido-6-deoxy-2,3-bis(3,5-dimethylphenylcarbamate) showed the highest enantioselectivity towards the tested chiral analytes; the phenyl-heterogeneous (Ph-hetero) CS of amylose 6-(4-methylbenzamido)-6-deoxy-2,3-bis(3,5-dimethylphenylcarbamate) baseline separated the most chiral analytes; the phenyl-homogeneous (Ph-homo) CS of amylose 6-(3,5-dimethylbenzamido)-6-deoxy-2,3-bis(3,5-dimethylphenylcarbamate) also exhibited a good enantioseparation capability among the developed CSs. Regarding Ph-hetero CSs, the enantioselectivity depended on the combination of the substituent at 6-position and that at 2- and 3-positions; as for Ph-homo CSs, the enantioselectivity was related to the substituent at 2-, 3-, and 6-positions; with respect to 6-nonPh CSs, the retention factor of most analytes on the corresponding CSPs was lower than that on Ph-hetero and Ph-homo CSPs in the same mobile phases, indicating π–π interactions did occur during enantioseparation. Although the substituent at 6-position could not provide π–π interactions, the 6-nonPh CSs demonstrated an equivalent or even higher enantioselectivity compared with the Ph-homo and Ph-hetero CSs.
Preparation of a novel bridged bis(β-cyclodextrin) chiral stationary phase by thiol-ene click chemistry for enhanced enantioseparation in HPLC
Gong, Bolin,Guo, Siyu,Zhang, Ning
, p. 35754 - 35764 (2021/12/02)
A bridged bis(β-cyclodextrin) ligand was firstly synthesized via a thiol-ene click chemistry reaction between allyl-ureido-β-cyclodextrin and 4-4′-thiobisthiophenol, which was then bonded onto a 5 μm spherical silica gel to obtain a novel bridged bis(β-cyclodextrin) chiral stationary phase (HTCDP). The structures of HTCDP and the bridged bis(β-cyclodextrin) ligand were characterized by the 1H nuclear magnetic resonance (1H NMR), solid state 13C nuclear magnetic resonance (13C NMR) spectra spectrum, scanning electron microscope, elemental analysis, mass spectrometry, infrared spectrometry and thermogravimetric analysis. The performance of HTCDP in enantioseparation was systematically examined by separating 21 chiral compounds, including 8 flavanones, 8 triazole pesticides and 5 other common chiral drugs (benzoin, praziquantel, 1-1′-bi-2-naphthol, Tr?ger's base and bicalutamide) in the reversed-phase chromatographic mode. By optimizing the chromatographic conditions such as formic acid content, mobile phase composition, pH values and column temperature, 19 analytes were completely separated with high resolution (1.50-4.48), in which the enantiomeric resolution of silymarin, 4-hydroxyflavanone, 2-hydroxyflavanone and flavanone were up to 4.34, 4.48, 3.89 and 3.06 within 35 min, respectively. Compared to the native β-CD chiral stationary phase (CDCSP), HTCDP had superior enantiomer separation and chiral recognition abilities. For example, HTCDP completely separated 5 other common chiral drugs, 2 flavanones and 3 triazole pesticides that CDCSP failed to separate. Unlike CDCSP, which has a small cavity (0.65 nm), the two cavities in HTCDP joined by the aryl connector could synergistically accommodate relatively bulky chiral analytes. Thus, HTCDP may have a broader prospect in enantiomeric separation, analysis and detection. This journal is
Enantioselective synthesis of ammonium cations
Walsh, Mark P.,Phelps, Joseph M.,Lennon, Marc E.,Yufit, Dmitry S.,Kitching, Matthew O.
, p. 70 - 76 (2021/09/06)
Control of molecular chirality is a fundamental challenge in organic synthesis. Whereas methods to construct carbon stereocentres enantioselectively are well established, routes to synthesize enriched heteroatomic stereocentres have garnered less attention1–5. Of those atoms commonly present in organic molecules, nitrogen is the most difficult to control stereochemically. Although a limited number of resolution processes have been demonstrated6–8, no general methodology exists to enantioselectively prepare a nitrogen stereocentre. Here we show that control of the chirality of ammonium cations is easily achieved through a supramolecular recognition process. By combining enantioselective ammonium recognition mediated by 1,1′-bi-2-naphthol scaffolds with conditions that allow the nitrogen stereocentre to racemize, chiral ammonium cations can be produced in excellent yields and selectivities. Mechanistic investigations demonstrate that, through a combination of solution and solid-phase recognition, a thermodynamically driven adductive crystallization process is responsible for the observed selectivity. Distinct from processes based on dynamic and kinetic resolution, which are under kinetic control, this allows for increased selectivity over time by a self-corrective process. The importance of nitrogen stereocentres can be revealed through a stereoselective supramolecular recognition, which is not possible with naturally occurring pseudoenantiomeric Cinchona alkaloids. With practical access to the enantiomeric forms of ammonium cations, this previously ignored stereocentre is now available to be explored.