- Regioselective Synthesis of 4,7,12,15-Tetrasubstituted [2.2]Paracyclophanes: A Modular Route Involving Optical Resolution
-
A practical synthetic method for preparing bis-(para)-pseudo-ortho and bis-(para)-pseudo-meta type 4,7,12,15-tetrasubstituted [2.2]paracyclophanes is reported. Regioselective double Rieche formylation was successfully applied to the corresponding dibromo[2.2]paracyclophanes under slightly modified conditions. Aldehydes reacted in an unknown direction with Rieche formylation agents, dichloromethyl methyl ether and titanium(IV) tetrachloride, leading to the formation of benzal chlorides. Formylated products were obtained after hydrolysis of these benzal chloride derivatives. Optical resolution was performed with the diastereomer method and (RP)-4,12-dibromo-7,15-diformyl[2.2]paracyclophane was successfully obtained in an enantiomerically pure form (99 % ee). Their synthetic utility is demonstrated with some exploratory transformations to access corresponding differently functionalized tetrasubstituted [2.2]paracyclophane derivatives.
- Biliz, Fatmanur,Cakici, Murat
-
supporting information
p. 4828 - 4834
(2021/09/20)
-
- Influencing the Self-Sorting Behavior of [2.2]Paracyclophane-Based Ligands by Introducing Isostructural Binding Motifs
-
Two isostructural ligands with either nitrile (Lnit) or isonitrile (Liso) moieties directly connected to a [2.2]paracyclophane backbone with pseudo-meta substitution pattern have been synthesized. The ligand itself (Lnit) or its precursors (Liso) were resolved by HPLC on a chiral stationary phase and the absolute configuration of the isolated enantiomers was assigned by XRD analysis and/or by comparison of quantum-chemical simulated and experimental electronic circular dichroism (ECD) spectra. Surprisingly, the resulting metallosupramolecular aggregates formed in solution upon coordination of [(dppp)Pd(OTf)2] differ in their composition: whereas Lnit forms dinuclear complexes, Liso exclusively forms trinuclear ones. Furthermore, they also differ in their chiral self-sorting behavior as (rac)-Liso undergoes exclusive social self-sorting leading to a heterochiral assembly, whereas (rac)-Liso shows a twofold preference for the formation of homochiral complexes in a narcissistic self-sorting manner as proven by ESI mass spectrometry and NMR spectroscopy. Interestingly, upon crystallization, these discrete aggregates undergo structural transformation to coordination polymers, as evidenced by single-crystal X-ray diffraction.
- Bohle, Fabian,Grimme, Stefan,Lützen, Arne,Rissanen, Kari,Schnakenburg, Gregor,Schneider, Andreas,Struch, Niklas,Topi?, Filip,Volbach, Lucia
-
-
- Synthesis, chiral resolution, and absolute configuration of dissymmetric 4,15-difunctionalized [2.2]paracyclophanes
-
Despite the fact that functionalized planar chiral [2.2]paracyclophanes have received a lot of attention, the chemistry of pseudo-meta 4,15-distubstituted [2.2]paracyclophanes is largely unexplored. This is mainly due to the fact that the 4,5-dibromo-functionalized [2.2]paracyclophane is much less prone to halogen-metal exchange reactions than its constitutional pseudo-ortho or pseudo-para isomers. Here, we give an account of an efficient protocol to achieve this, which allows the synthesis of a broad variety of 4,15-disubstituted [2.2]paracyclophanes. Furthermore, we were able to resolve several of the racemic compounds via chiral HPLC and assign the absolute configurations of the isolated enantiomers by X-ray diffraction and/or by the comparison of calculated and measured CD-spectra.
- Meyer-Eppler, Georg,Sure, Rebecca,Schneider, Andreas,Schnakenburg, Gregor,Grimme, Stefan,Lützen, Arne
-
p. 6679 - 6687
(2014/08/05)
-
- Symmetrically tetrasubstituted [2.2]paracyclophanes: Their systematization and regioselective synthesis of several types of bis-bifunctional derivatives by double electrophilic substitution
-
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
-
experimental part
p. 4600 - 4617
(2009/05/08)
-
- Cyclophanes. Part LII: Ethynyl[2.2]paracyclophanes - New building blocks for molecular scaffolding
-
The synthesis of seven ethynyl[2.2]paracyclophanes is described. The five diethynyl derivatives 4,5-diethynyl[2.2]paracyclophane (12), pseudo-gem-(13), pseudo-ortho-(14), pseudo-meta-(15), and pseudo-para-diethynyl[2.2] paracyclophane (16), the tetraethynyl compound 4,7,13,16-tetraethynyl[2.2] paracyclophane (17), and for comparison the mono-ethynylated hydrocarbon 4-ethynyl[2.2]paracyclophane (11) have been prepared. The structures of these new building blocks for carbon rich systems were determined by the usual analytical and spectroscopic methods.
- Bondarenko, Lidija,Dix, Ina,Hinrichs, Heino,Hopf, Henning
-
p. 2751 - 2759
(2007/10/03)
-
- THE FIRST THREE AROMATIC TRIBROMIDES OF THE PARACYCLOPHANE SERIES
-
From the reaction mixtures in the uncatalyzed polybromination of paracyclophane by the action of excess Br2 in CCl4, there have been found along with the known products - 4,15- and 4,16-dibromoparacyclophanes - two new aromatic tribromides of this series, which have been isolated in pure form; 4,12,15- and 4.15.16-tribromoparacyclophanes.Special experiments demonstrated that the mixtures of these tribromides are formed as a result of competitive monobromination of 4,15-dibromoparacyclophane; the 4,15,16-tribromoparacyclophane, together with still another newly isolated isomer of this series - 4,8,12-tri bromoparacyclophane - is formed as a result of competitive monobromination of 4,16-dibromoparacyclophane.As an explanation of the features of the orienting effect of substituents in these competing reactions, a rule was proposed: On the conventional orientation (from the electronic point of view) of entry of the bromine atom into the substituted ring (para > ortho > meta), a steric limitation is imposed on its attack in the pseudo-gem-position, owing to the bulky bromine atom that is transannularly positioned above it in the neighboring aromatic ring.The structures of all of the tribromides were established on the basis of elemental analyses, mass spectrometry, and 1H NMR spectrometry (including PMR using the homonuclear Overhauser effect).The data obtained in this work indicate that the 4,12,15-tribromoparacyclophane and 4,15,16-tribromoparacyclophane are predecessors of the two tetrabromides previously obtained by Cram - 4,7,12,15- and 4,5,15,16-tetrabromoparacyclophanes: and the 4,8,12-tribromoparacyclophane is a possible predecessor of 4,8,12,16-tetrabromoparacyclophane, which is unknown up to the present time . Keywords: paracyclophane, dibromoparacyclophane, tribromoparacyclophane.
- Nikanorov, V. A.,Kharitonov, V. G.,Yatsenko, E. V.,Krut'ko, D. P.,Galakhov, M. V.,et al.
-
p. 1430 - 1434
(2007/10/02)
-
- Samarium(II) Diiodide Mediated Coupling of Bis(bromomethyl)arenes. Facile Synthesis of n>Cyclophanes without using High-Dilution Techniques
-
In the presence of samarium(II) diiodide (Sml2), coupling of 1,3- and 1,4-bis(bromomethyl)benzenes proceeds smoothly to give their cyclic and acyclic oligomers.Use of 1.2 equiv. of Sml2 gives 1,2-bis(3- and 4-bromomethylphenyl)ethanes, respectively, in 95percent yield, and the use of 5.0 equiv. of Sml2 affords n>metacyclophanes and n>paracyclpphanes (n = 2, 3 and 4), respectively, in satisfactory yields.By using 5.0 equiv. of Sml2, 2-bromo- and 2-methoxy-1,4-bis(bromomethyl)benzenes and 1,4- and 2,6-bis(bromomethyl)naphthalenes each give only one of several expected isomeric cyclophanes as the major cyclic oligomer.
- Takahashi, Senji,Mori, Nobuo
-
p. 2029 - 2032
(2007/10/02)
-
- Molecular Design and Model Experiments of Ferromagnetic Intermolecular Interaction in the Assembly of High-Spin Organic Molecules. Generation and Characterization of the Spin States of Isomeric Bis(phenylmethylenyl)paracyclophanes
-
The electron spin-spin interaction between the two triplet diphenylcarbene units incorporated in the paracyclophane skeleton has been investigated by ESR spectroscopy.Pseudoortho, pseudometa, and pseudopara didiazoparacyclophanes (4a-c) were pre
- Izuoka, Akira,Murata, Shigeru,Sugawara, Tadashi,Iwamura, Hiizu
-
p. 2631 - 2639
(2007/10/02)
-