- Highly Efficient Kinetic Resolution of PHANOL by Chiral Phosphoric Acid Catalyzed Asymmetric Acylation
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We report herein a highly efficient kinetic resolution of PHANOL by chiral phosphoric acid catalyzed asymmetric acylation. PHANOL enantiomers were well differentiated by the chiral environment of chiral phosphoric acid, and both the corresponding monoester and PHANOL were obtained with excellent enantioselectivities (98% ee and 92% ee, respectively). Detailed examination of the substrates suggests that the presence of two hydroxy groups in PHANOL was critical for both reactivity and enantioselectivity.
- Mori, Keiji,Kishi, Hiroki,Akiyama, Takahiko
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- Development of Planar Chiral Iodoarenes Based on [2.2]Paracyclophane and Their Application in Catalytic Enantioselective Fluorination of β-Ketoesters
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The design and synthesis of novel planar chiral iodoarenes based on [2.2]paracyclophane is reported. A process of highly enantioselective oxidative fluorination of a β-ketoester with 3HF-Et3N as a nucleophilic fluoride source mediated by these new hypervalent iodine catalysts has been developed. This represents the first highly enantioselective reaction catalyzed by planar chiral hypervalent iodine.
- Wang, Yang,Yuan, Hang,Lu, Hongfei,Zheng, Wen-Hua
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- Improved synthesis of enantiopure 4-hydroxy[2.2]paracyclophane
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(Figure presented) 4-Hydroxy[2.2]paracyclophane is readily prepared via an improved synthetic protocol from unsubstituted [2.2]paracyclophane. The key step is a Dakin oxidation of 4-formyl[2.2]paracyclophane. This allows a rapid access to large quantities of the product and an easy synthesis of the enantiopure form.
- Friedmann, Christian J.,Ay, Sefer,Braese, Stefan
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- 3D Coumarin Systems Based on [2.2]Paracyclophane: Synthesis, Spectroscopic Characterization, and Chiroptical Properties
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In this article, we report the preparation of a series of [2.2]paracyclophane-fused coumarin systems through a simple and general procedure involving a transition-metal-catalyzed cyclization of aryl alkynoates as the key step. We also highlight the influence of the [2.2]paracyclophane (pCp) motif and its "phane" interactions on the spectroscopic properties of the newly synthesized fluorophores, which emit in the blue-green region of the visible spectrum (?em up to 560 nm) and show extremely large Stokes shifts (up to 230 nm). Finally, we demonstrate that our straightforward approach can easily be used to access optically active planar chiral 3D coumarins. Compared to previously described fluorescent paracyclophanes and other organic dyes, our compact heteroaromatic derivatives show promising chiroptical properties, both in term of circular dichroism (gabs 8 × 10 -3) and circularly polarized luminescence (glum 5 × 10 -3), thus demonstrating a practical application of our synthetic method.
- Delcourt, Marie-Léonie,Reynaud, Corentin,Turcaud, Serge,Favereau, Ludovic,Crassous, Jeanne,Micouin, Laurent,Benedetti, Erica
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- Planar-chiral building blocks for metal-organic frameworks
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The first example of a planar-chiral building block being used for chiral metal-organic frameworks (MOFs) is presented. The porous MOF structure combined with the chiral properties of the planar linker allows a selective adsorption, demonstrated for a nonpolar terpene limonene in thin surface-mounted MOF films.
- Cakici, Murat,Gu, Zhi-Gang,Nieger, Martin,Bürck, Jochen,Heinke, Lars,Br?se, Stefan
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- Enzymatic kinetic resolution of (±)-4-acetoxy[2.2] paracyclophane by candida cylindracea lipase. An efficient route for the preparation of(+)-R-4-Hydroxy- and (+)-S-4-acetoxy[2.2)paracyclophane
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The enzymatic kinetic resolution of (±)-4-acetoxy[2.2]paracyclophane by Candida cylindracea lipase was investigated in water and in a two-phase aqueous organic system. The (+)-(R)4-hydroxy- and (c)-(S)-4-acetoxy[2,2]-paracyclophanes were isolated in excellent yields and high enantiomeric excesses. The resolution was carried out on multi-gram scale in hexane-water at 40°C.
- Cipiciani, Antonio,Fringuelli, Francesco,Mancini, Vittorio,Piermatti, Oriana,Scappini, Anna Maria,Ruzziconi, Renzo
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- Photochromism of novel chromenes constrained to be part of [2.2]paracyclophane: Remarkable 'phane' effects on the colored o-quinonoid intermediates
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The photochemistry of rationally designed chromenes that are constrained to be part of [2.2]paracyclophane, i.e., CP-H and CP-OMe, was investigated to examine the effect of through-space delocalization in the cyclophane core (phane effect) on the photochr
- Moorthy, Jarugu Narasimha,Mandal, Susovan,Kumar, Amrit
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- Synthesis of planar chiral [2.2]paracyclophane monophosphine ligands and their application in the umpolung allylation of aldehydes
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Chiral [2.2]paracyclophane monophosphines 8 were synthesized via resolution using chiral palladacycle 10. Chiral phosphinite 5 was also prepared from 4-hydroxy[2.2]paracyclophane. Phosphines 8 and phosphinite 5 were used as the ligand in the umpolung ally
- Zhang, Tang-Zhi,Dai, Li-Xin,Hou, Xue-Long
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- Synthesis of bis(benzoxazole) frameworks chiralized by planar chiral [2.2]Paracyclophane
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In this study, a new class of chiral bis(benzoxazole) has been synthesized. The bis(benzoxazole) framework, which has an achiral structure was chiralized by a planar chiral [2.2]paracyclophane moiety. Both enantiomeric forms of the bis(benzoxazole) deriva
- Polat, Emrah,Turbedaroglu, Ozge,Cakici, Murat
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- Influence of pH and temperature on the enantioselectivity of propan-2-ol-treated Candida rugosa lipase in the kinetic resolution of (±)-4-acetoxy-[2,2]-paracyclophane
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The reaction temperature, pH of the aqueous medium and use of an aqueous-n-hexane reaction medium markedly influenced the hydrolysis rate and enantioselectivity of (±)-4-acetoxy-[2,2]-paracyclophane with propan-2-ol-treated Candida rugosa lipase. The results have been justified on the basis of a possible conformational change in the enzyme as a consequence of the displacement of its polypeptide lid.
- Cipiciani, Antonio,Bellezza, Francesca,Fringuelli, Francesco,Silvestrini, Maria Grazia
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- Novel strategy for the synthesis of chiral pseudo-ortho-substituted hydroxy[2.2]paracyclophane-based ligands from the resolved 4-bromo-12-hydroxy[2.2]paracyclophane as a parent compound
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A simple and efficient resolution of racemic 4-bromo-12-hydroxy[2.2]paracyclophane into its enantiomers via diastereomeric esters with (1S)-(-)-camphanic acid was carried out. New synthetic routes to enantiomerically pure 4,12-dihydroxy- and 4-hydroxy[2.2]paracyclophanes starting from the enantiomers of an intermediate 4-bromo-12-hydroxy[2.2]paracyclophane are proposed.
- Zhuravsky, Roman,Starikova, Zoya,Vorontsov, Evgenii,Rozenberg, Valeria
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- An exploration of Suzuki aryl cross coupling chemistry involving [2.2]paracyclophane derivatives
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Suzuki aryl cross coupling reactions using derivatives of [2.2]paracyclophane were examined. A variety of aryl boronic acids and pinacolate esters were successfully cross coupled with 4-bromo[2.2] paracyclophane under standard Suzuki conditions. Whilst an
- Roche, Alex J.,Canturk, Belgin
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- Planar chiral hydroxy derivatives of [2.2]paracyclophane as auxiliaries for asymmetric allylboration
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Allylboronic esters with various structures were synthesized for the first time based on [2.2]paracyclophane derivatives containing one or two hydroxy groups. It was demonstrated that these esters can be used as chiral inductors in the asymmetric allylboration of benzaldehyde. The highest enantiomeric excess of 1-phenylbut-3-en-1-ol (60%) was achieved in the reactions with acyclic bis-O,O-(paracyclophanyl) allylboronates based on (S)-4-hydroxy-and (S)-12-bromo-4-hydroxy[2.2]paracyclophanes. (S)-4-Hydroxy[2.2]paracyclophane was studied by X-ray diffraction.
- Vorontsova,Zhuravsky,Sergeeva,Vorontsov,Starikova,Rozenberg
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- Chiral isothiourea-catalyzed kinetic resolution of 4-hydroxy[2.2]paracyclophane
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We herein report a method for the kinetic resolution of racemic 4-hydroxy[2.2]paracyclophane by means of a chiral isothiourea-catalyzed acylation with isobutyric anhydride. This protocol allows for a reasonable synthetically useful s-factor of 20 and provides a novel entry to obtain this interesting planar chiral motive in an enantioenriched manner.
- Weinzierl, David,Waser, Mario
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p. 800 - 804
(2021/05/03)
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- Tuning the Reactivity of Peroxo Anhydrides for Aromatic C-H Bond Oxidation
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Phenol moieties are key structural motifs in many areas of chemical research from polymers to pharmaceuticals. Herein, we report on the design and use of a structurally demanding cyclic peroxide (spiro[bicyclo[2.2.1]heptane-2,4′-[1,2]dioxolane]-3′,5′-dione, P4) for the direct hydroxylation of aromatic substrates. The new peroxide benefits from high thermal stability and can be synthesized from readily available starting materials. The aromatic C-H oxidation using P4 exhibits generally good yields (up to 96%) and appreciable regioselectivities.
- Pilevar, Afsaneh,Hosseini, Abolfazl,?ekutor, Marina,Hausmann, Heike,Becker, Jonathan,Turke, Kevin,Schreiner, Peter R.
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p. 10070 - 10079
(2018/09/06)
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- Synthesis of bromo-substituted 4-hydroxy[2.2]paracyclophanes and [2.2]paracyclophane-4,7-quinones as versatile chiral building blocks
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Approaches to a number of bromo-substituted derivatives of 4-hydroxy[2.2]paracyclophane, including the regioselective mono- and dibromination of this phenol, were investigated. The applicability of the regioisomeric monobromo-substituted phenols for the synthesis of substituted [2.2]paracyclophane-4,7-quinones through a one-pot diazonium coupling/reduction/oxidation sequence was demonstrated. The compounds obtained possess various substitution patterns and could be used for the synthesis of a wide range of [2.2]paracyclophane derivatives by transformation of the bromine, hydroxy, and quinoid fragments.
- Atman, Natalia V.,Zhuravsky, Roman P.,Antonov, Dmitrii Yu,Sergeeva, Elena V.,Godovikov, Ivan A.,Starikova, Zoya A.,Vologzhanina, Anna V.
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supporting information
p. 325 - 330
(2015/03/03)
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- Modular synthesis of planar-chiral para-substituted paracyclophanes by double Suzuki coupling
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The first synthesis of enantiomerically pure 4,7-paracyclophane ditriflate starting from a quinone was reported. Using this molecule, mono-or dicoupling with boronic acids delivered enantiomerically pure arylparacyclophanes.
- Cakici, Murat,Braese, Stefan
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p. 6132 - 6135
(2013/01/15)
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- Unprecedented directing group ability of cyclophanes in arene fluorinations with diaryliodonium salts
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For the first time it is shown that exceptionally electron-rich arene rings can be fluorinated exclusively during the reductive elimination reactions of diaryliodonium fluorides. The 5-methoxy[2.2]paracyclophan-4-yl directing group simultaneously reduces unproductive aryne chemistry and eliminates ligand exchange reactions by a combination of steric and electronic effects. Use of the cyclophane directing group permits an unprecedented degree of control in fluorination reactions of diaryliodonium salts.
- Graskemper, Joseph W.,Wang, Bijia,Qin, Linlin,Neumann, Kiel D.,Dimagno, Stephen G.
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p. 3158 - 3161
(2011/08/06)
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- Regiospecific reductive elimination from diaryliodonium salts
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(Figure Presented) Out-of-plane steric bulk furnished by a cyclophane substituent on iodine(III) strongly destabilizes the transition state in the reductive elimination from diaryliodonium salts and leads to regiochemical control (dubbed SECURE), as is demonstrated by computational and experimental studies. This approach should be general for high-valent maingroup and transition metal ions. X=N3, OAc, PhO, CF3CH2O, SCN, PhS.
- Wang, Bijia,Graskemper, Joseph W.,Qin, Linlin,DiMagno, Stephen G.
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supporting information; experimental part
p. 4079 - 4083
(2010/08/07)
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- Towards a flexible strategy for the synthesis of enantiomerically pure [2.2]paracyclophane derivatives: The chemistry of 4-tolylsulfinyl[2.2] paracyclophane
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The use of enantiomerically enriched 4-tolylsulfinyl[2.2]paracyclophane as a precursor to a variety of mono- and di-substituted [2.2]paracyclophane derivatives is described. The goal of our research is to develop a single general precursor that permits the synthesis of the most common [2.2]paracyclophane substitution patterns. The chemistry of two diastereoisomers of 4-tolylsulfinyl[2.2]paracyclophane has been explored and it facilitates the synthesis of enantiomerically enriched 4-substituted and 4,13-disubstituted [2.2]paracyclophanes. Directed lithiations result in an unusual cyclisation reaction. Whilst the tolyl group cannot realise our goal, the chemistry outlined acts as a successful proof of concept.
- Parmar, Rakesh,Coles, Martyn P.,Hitchcock, Peter B.,Rowlands, Gareth J.
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experimental part
p. 4177 - 4187
(2011/02/25)
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- Symmetrically tetrasubstituted [2.2]paracyclophanes: Their systematization and regioselective synthesis of several types of bis-bifunctional derivatives by double electrophilic substitution
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The possible number of chiral and achiral tetrasubstituted [2.2]paracyclophanes possessing different types of symmetry (C2, Ci, Cs, C2., C2h) is evaluated and a unified independent trivial naming descriptor system is introduced. The reactivity and regioselectivity of the electrophilic substitution of the chiral pseudo-mefaand achiral pseudo-para-disubstituted [2.2]paracyclophanes are investigated in an approach suggested to be general for the synthesis of bis-bifunctional [2.2]paracyclophanes. The mono- and diacylation of chiral pseudo-meta-dihydroxy[2.2]paracyclophane 14 with acetylchloride occur ortho-regioselectively to produce tri- 22, 23 and symmetrically 21 tetrasubstituted acyl derivatives. The same reaction with benzoylchloride is neither regio-, nor chemoselective, and gives rise to a mixture of ortho-lpara-, mono-/diacylated compounds 27-31. The double acylation of pseudo-meta- dimethoxy[2.2]paracyclophane 18 is completely para-regioselective. Electrophilic substitution of pseudo-wera-bis(methoxycarbonyl)[2.2]paracyclophane 20 regioselectively generates the pseudo-gem-substitution pattern. Formylation of this substrate produces the monocarbonyl derivatives 35 only, whereas the Fe-catalyzed bromination may be directed towards mono- 36 or disubstitution 37 products chemoselectively by varying the reactions conditions. The diacylation and dibromination reactions of the respective achiral diphenol 12 and bis(methoxycarbonyl) 40 derivatives of the pseudo-para-structure retain regioselectivities which are characteristic for their pseudo-mefa-regioisomers. Imino ligands 26, 25, and 39, which were obtained from monoacyl- 22 and diacyldihydroxy[2.2]paracyclophanes 21, 38, are tested as chiral ligands in stereoselective Et2Zn addition to benzaldehyde producing 1-phenylpropanol with ee values up to 76%.
- Vorontsova, Natalia V.,Rozenberg, Valeria I.,Sergeeva, Elena V.,Vorontsov, Evgenii V.,Starikova, Zoya A.,Lyssenko, Konstantin A.,Hopf, Henning
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body text
p. 4600 - 4617
(2009/05/08)
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- The synthesis of enantiomerically pure [2.2]paracyclophane derivatives
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[2.2]Paracyclophane is a fascinating molecule that offers great potential in a wide range of chemical disciplines. Currently, the synthesis of the majority of enantiomerically pure [2.2]paracyclophane derivatives is based on the resolution of a small numb
- Rowlands, Gareth J.
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scheme or table
p. 1527 - 1534
(2008/10/09)
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- The first examples of planar chiral organic benzimidazole derivatives
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The synthesis of a number of novel planar chiral benzimidazoles from [2.2]paracyclophane is reported. The key steps include a Buchwald-Hartwig amination of a sterically demanding inflate and the functionalisation of the C-2 bromide. Georg Thieme Verlag St
- Hitchcock, Peter B.,Hodgson, Andrew C. C.,Rowlands, Gareth J.
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p. 2625 - 2628
(2008/09/16)
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- The synthesis of enantiomerically pure 4-substituted [2.2]paracyclophane derivatives by sulfoxide-metal exchange
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A general strategy for the synthesis of enantiomerically pure 4-substituted [2.2]paracyclophanes from a common sulfoxide precursor is described. The Royal Society of Chemistry 2005.
- Hitchcock, Peter B.,Rowlands, Gareth J.,Parmar, Rakesh
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p. 4219 - 4221
(2007/10/03)
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- Improved synthesis of (±)-4,12-dihydroxy[2.2]paracyclophane and Its enantiomeric resolution by enzymatic methods: Planar chiral (R)- and (S)-phanol
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(±)-4,12-Dihydroxy[2.2]paracyclophane [(±)-PHANOL] is readily prepared from [2.2]paracyclophane by an improved synthetic protocol. Enzymatic kinetic resolution of its bis-acetate proceeds with good enantioselection. Separation, hydrolysis, and recrystallization provides both enantiomers of PHANOL in high enantiopurity.
- Braddock, D. Christopher,MacGilp, Iain D.,Perry, Benjamin G.
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p. 8679 - 8681
(2007/10/03)
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- Resolution and novel reactions of 4-hydroxy[2.2]paracyclophane
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The resolution of racemic 4-hydroxy[2.2]paracyclophane (1) by fractional crystallization of the diastereomeric esters 3 with (1S)-(-)-camphanic acid and the determination of the absolute configurations of (R)- and (S)-4-hydroxy[2.2]paracyclophanes by X-ra
- Rozenberg, Valeria,Danilova, Tat'yana,Sergeeva, Elena,Vorontsov, Evgenii,Starikova, Zoya,Korlyukov, Aleksandr,Hopf, Henning
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p. 468 - 477
(2007/10/03)
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- Preparation of planar chiral amino phenols based on the [2.2]paracyclophane backbone
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The synthesis of various planar and central chiral secondary and tertiary amino phenols based on the [2.2]paracyclophane backbone is described. Planar chiral tertiary amino phenols are prepared by reductive amination of 5-formyl-4-hydroxy[2.2]paracyclopha
- Dahmen, Stefan,Braese, Stefan
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p. 2845 - 2850
(2007/10/03)
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- A novel entry into a new class of cyclophane derivatives: Synthesis of (±)-[2.2]paracyclophane-4-thiol
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Two syntheses of (±)-[2.2]paracyclophane-4-thiol have been accomplished in two and five steps, with overall yields of 46 and 31%, respectively, from [2.2]paracyclophane. The strategy involves two key reactions: (a) a lithium aluminium hydride reduction of the disulphide of [2.2]paracyclophane and (b) the use of a Newman-Kwart reaction for the conversion of [2.2]paracyclophane-4-ol to [2.2]paracyclophane-4-thiol.
- Kane, Vinayak V.,Gerdes, Anton,Grahn, Walter,Ernst, Ludger,Dix, Ina,Jones, Peter G,Hopf, Henning
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p. 373 - 376
(2007/10/03)
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- Chemoenzymatic synthesis of optically pure planar chiral (S)-(-)-5-formyl-4-hydroxy[2.2]paracyclophane
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The synthesis of optically pure (S)-5-formyl-4-hydroxy-[2.2]paracyclophane (S)-3 (ee > 99 %) was achieved by a three-step chemoenzymatic procedure consisting of (i) kinetic enzymatic resolution of (R,S)-4-acetoxy[2.2]paracyclophane (R,S)-1 to produce optically pure starting material, which after (ii) hydrolysis was subjected to (iii) stereoselective ortho-formylation with an overall yield of 51 %. All attempts to use a biocatalyst directly for the preparation of optically pure disubstituted [2.2]paracyclophanes failed because of either total lack of activity (bioreduction) or low enantioselectivities of the enzymes screened (hydrolases). Using the chemoenzymatic approach from (R,S)- 1, optically pure (S)-1 and after subjecting (S)-1 to hydrolysis and finally to formylation (S)-3 was obtained. As confirmed by chiral GC, hydrolysis and formylation took place without racemization. During the optimization of the enzymatical part of the synthesis a strong influence of both the nature of the cosolvent and the pH of the buffer-phase on the enantioselectivity value E were observed. Using a two-phase system consisting of diethyl ether and phosphate buffer an E value higher than 100 was achieved at a pH of 7.0 and at room temperature.
- Pamperin, Dirk,Schulz, Christian,Hopf, Henning,Syldatk, Christoph,Pietzsch, Markus
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p. 1441 - 1445
(2007/10/03)
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- Synthesis of Chiral (R)-4-Hydroxy- and (R)-4-Halogeno[2.2]paracyclophanes and Group Polarizability. Optical Rotation Relationship
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(R)-4-Hydroxy-, -4-fluoro-, -4-bromo-, and -4-iodo[2.2]paracyclophanes have been prepared and their absolute configuration assigned on the basis of chemical correlations. Different relationships between the specific optical rotation and the group polarizability have been found depending on the ability of the substituents to conjugate with the aromatic ring. At least for 4,7-disubstituted [2.2]paracyclophanes, the effects of the substituents on the specific rotation seem to be additive, independent of the wavelength used. An equation has been derived which allows to predict, to a satisfactory approximation, the [α] values of 4-X-7-methyl[2.2]paracyclophanes whenever the group polarizability of the substituents is known.
- Cipiciani, Antonio,Fringuelli, Francesco,Mancini, Vittorio,Piermatti, Oriana,Pizzo, Ferdinande,Ruzziconi, Renzo
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p. 3744 - 3747
(2007/10/03)
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- Transition Metal Catalyzed Oxidations, 3. Reaction of 4-Hydroxyparacyclophane with the Mimoun Molybdenum Oxodiperoxo Complex *Py*HMPT
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Treatment of 4-hydroxyparacyclophane (1) with the Mimoun molybdenum oxodiperoxo complex *Py*HMPT gives 3,4-dihydro-3-hydroxy-4-oxoparacyclophane (4).This dienone dimerizes at room temperature to afford the Diels-Alder adduct 5, whose structure was confirmed by X-ray analysis.
- Krohn, Karsten,Rieger, Hagen,Hopf, Henning,Barrett, David,Jones, Peter G.,Doering, Detlev
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p. 1729 - 1732
(2007/10/02)
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- Anomalous Hydrolysis Behaviour of Paracyclophanediazonium Salts: a New Route to Bridged Benzobarrelenes
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The hydrolysis of diazotized 5-amino-paracyclophane and anti-4-amino-(1,4)naphthalenoparacyclophane gives products having a barrelene structure, presumably via an aryne mechanism.
- Mori, Nobuo,Takemura, Tetsuo,Tsuchiya, Kazahiko
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p. 575 - 576
(2007/10/02)
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