Troger's Base Research Articles

Preparation ofTröger Base Derivatives by Cross-Coupling Methodologies

Derivatives of the Troger base are finding increasing application in supramolecular chemistry: they are introduced as rigid scaffolds into synthetic receptors and 'molecular torsional balances' to quantify weak intermolecular interactions, and serve as efficient 'covalent templates' in the tether-directed remote functionalization of fullerenes. This paper describes the facile synthesis of symmetrically (Schemes 1 and 2) and unsymmetrically (Schemes 4 and 5) substituted Troger base derivatives starting from the corresponding, readily available dihalo compounds. A variety of metal-catalyzed cross-coupling reactions, including Suzuki couplings, palladium-catalyzed cyanation and boronation, and copper-catalyzed amidations are used to achieve these transformations. © 2005 Verlag Helvetica Chimica Acta AG.

A Desymmetrization Route to Fused Tröger's Base Analogues: Synthesis, Isolation, and Characterization of the First Anti-Anti Diastereomer of a Fused Tris-Tröger's Base Analogue

A desymmetrization route to fused Troger's base analogues was developed. In this way, the synthesis of the first example of an anti-anti diastereomer of a fused tris-Troger's base analogue was accomplished. The resulting compound 5b is a nonlinear symmetric regioisomer obtained from p-bromoaniline in 7% yield. The corresponding syn-anti diastereomer 5a was obtained in 4% yield.

Thiooxamide chiral stationary phase for liquid chromatography

A new chiral stationary phase was prepared by reaction of aminopropylsilica with N-(α-phenylethyl)chloroacetamide in the presence of sulfur and used for the high performance liquid-chromatographic separation of 1,1′-binaphthyl-2,2′-diol and Troger's base enantiomers.

Synthetic Routes to Linear Oligo-Tröger's Bases

Derivatives of Tröger's base (TB) have played important roles in receptor construction due to their rigid V-shape. A new class of these compounds are the oligo-TBs, which can function as cavitands. Herein, we describe both stepwise and one-step (oligomerization) methods suitable for the preparation of linear oligo-TBs.

Application of the polarizability theory to the calculation of anisotropic circular dichroism spectra

We derive a general expression of the circular dichroism spectra of anisotropically distributed chiral molecules in the polarizability framework by introducing a tensorial rotational strength. Example calculation is carried out on an acridine-substituted Troger base. It is shown that the circular dichroism is very sensitive to the direction propagation of the light beam.

Solid‐Liquid Equilibrium of Tröger's Base Enantiomers in Ethanol: Experiments and Modelling

AbstractThermodynamic properties of the enantiomers of the Tröger's base as crystals and in ethanol solutions have been studied by means of a suite of analytical techniques. We report the melting diagrams of the two enantiomers, providing evidence for the formation of a solid racemic compound. We present also ternary equilibrium data about the solubility of the two enantiomers in ethanol at 25°, 35°, and 50°. The melting‐diagram data are described well by the SchroederVan Laar and PrigogineVieland equations, when the melting temperatures and enthalpies of pure enantiomer and of the racemic compound are provided and with the assumption that the melting behavior is ideal. The ternary equilibrium data were well‐described when nonideality of mixtures of ethanol and the enantiomers is accounted for in terms of the non‐random two liquids (NRTL) model. Finally, we present the newly determined X‐ray crystal structure of an orthorhombic form of the pure Tröger's base (+)‐enantiomer.

A New Molecular Receptor Based on Thiophene Congener of Tröger’s Base: Selective Binding with Aliphatic and Aromatic Dicarboxylic Acids

A new molecular receptor bearing pyridylamino groups was prepared with a thiophene congener of Troger's base as a spacer, and was found to exhibit selective binding toward aliphatic and aromatic dicarboxylic acids, primarily depending on the length of the carbon chain.

4,4'-Diaminodiphenyl Sulfone, a Substituted Troger Base, and Its Functionalization by the Amino Group

Racemic mixtures of previously unknown chiral “tweezers” with a rigid asymmetrical diazocine bridge (Troger base) were synthesized on the basis of 4,4'-diaminodiphenyl sulfone. The Troger base was condensed with 2,4-dihydroxybenzaldehyde and 4-formylbenzoic acid to obtain new aromatic chelate cavities.

4,5,9,10-Tetrahydro-4,9-methanodithieno[3,2-b:3′,2′-f][1,5]diazocine

In the title compound, C11H10N2S2, which is the first thio­phene analogue of Troger's base, the dihedral angle between the two thio­phene rings is 100.73 (7)°.

Polarization Rotation in a Second Harmonic Reflection Experiment from an Isotropic Surface of Chiral Tröger Base

Polarization rotation in second harmonic reflection (ORD-SHR) is carefully investigated. After emphasizing the relevance of this technique for characterization of chiral molecules the optical activity of which arises from electric contributions, we bring an experimental demonstration with a specially synthesized acridine-substituted Troger base, which displays very strong rotations. Measurements of this rotation for wavelengths spanning the absorption spectrum are satisfactorily reproduced by a model based on coupled, anharmonic oscillators.

1H, 13C, and 15N NMR analysis of Tröger's base and of some of its [15N1] labelled precursors

AbstractOne‐ and two‐dimensional NMR spectra of Tröger's base, (±)‐2,8‐dimethyl‐6H,12H‐5,11‐methanodibenzo[b,f][1,5]diazocine labelled on one of the nitrogen atoms, have been used to determine the chemical shifts, coupling constants, and Δ13C(15N) isotope shifts. Copyright © 2002 John Wiley & Sons, Ltd.

Carbocyclic molecular clefts incorporating hydrogen bonding features

Chiral carbocyclic cleft molecules incorporating carbonyl, hydroxy, oxime, o-phenol and m-nitroaryl groups have been synthesised from dibenzobicyclo[b,f][3.3.1]nona-5a,6a-diene-6,12-dione, a carbocyclic analogue of Troger's base. These clefts contain similar features to Troger's base but in addition contain carbonyl groups, which are readily modified, on the chiral bridge that forms the molecular cleft. The oxime and m-nitroaryl derivatives have been characterised by single crystal X-ray diffraction. The dihedral angles between the two aromatic rings of these two molecules and those of previously reported related molecules are compared. Two crystal packing motifs are identified and found to influence the size of the dihedral cleft angle of this type of molecule.

Synthesis and functionalization of thiophene congeners of Tröger's base

Thiophene congeners of Troger's base were prepared by the reactions of 3-aminothiophenes and formaldehyde. Treatment of the thiophene congeners with BuLi or LDA resulted in the regioselective formation of the dianion at the 2- and 7-positions, which reacted with a variety of electrophiles such as trimethylsilyl chloride, iodine, NBS, DMF, benzophenone, and benzaldehyde. This reaction opens up a facile and versatile entry for a Troger's base skeleton with a variety of functional groups.

Design and Synthesis of a Novel Cyclophane as Host for Aryl Phosphate

A novel Troger base derived cyclophane bearing mercaptoimidazole groups on the alkyl chains as blanches of 6H,12H-5,11-methanodibenzo-[b,f][1,5]diazocine skeleton was synthesized in order to investigate the ability as macrocyclic enzyme models to incorporate phosphotyrosine in future.

Troger's base molecular scaffolds in dicarboxylic acid recognition.

Artificial receptors (1-5) have been designed and synthesized from simple precursors. The chain length selectivity studies of dicarboxylic acids within the cavities of new fluorescent Troger's base molecular frameworks (1-3) have been carried out with a critical examination of their role of rigidity as well as flexibility in selective binding in comparison to receptor 5. The chiral resolution of the racemic Troger's base receptors (1 and 2) by chiral recognition with (+)- camphoric acid using hydrogen-bonding interactions has been studied.

Stereointegrity of Tröger's Base: Gas-Chromatographic Determination of the Enantiomerization Barrier

Troger's base 1 (2,8-dimethyl-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine) undergoes enantiomerization in the gas and liquid phases. By enantioselective stopped-flow multidimensional gas chromatography, Eyring activation parameters of the enantiomerization barrier have been determined in the inert mobile gas phase (helium): ΔG⧧gas(298.15 K) = 112.8 ± 0.5 kJ mol-1; ΔH⧧gas = 62.7 ± 0.3 kJ mol-1; ΔS⧧gas = −168 ± 6 J (K mol)-1. An enantiomerization pathway proceeding via a degenerated retro-hetero-Diels−Alder ring opening or formation of a zwitterionic structure of 1 is proposed. By enantioselective dynamic gas chromatography, Eyring activation parameters have also been determined via computer-aided simulation of experimental interconversion peak profiles in the chiral stationary liquid phase: ΔG⧧liq(298.15 K) = 117.8 ± 0.5 kJ mol-1; ΔH⧧liq = 48.9 kJ mol-1; ΔS⧧liq = −231 ± 8 J (K mol)-1. Surprisingly, in the presence of the chiral stationary phase (CSP) Chirasil-β-Dex, required for enantiomer separation o...

Photoinduced energy and electron transfer in bis-porphyrins with quinoxaline Tröger's base and biquinoxalinyl spacers

The photophysical characterisation of bis-porphyrins consisting of two porphyrins bridged by either a quinoxaline Troger's base (1 and 2) or a biquinoxalinyl (3) spacer are reported. Efficient intramolecular electronic energy transfer (EET) between the rigidly linked free-base porphyrins in 1 and from the zinc(II) porphyrin to the free-base porphyrin in 2 has been investigated by steady-state absorption and emission spectroscopy, time-resolved fluorescence spectroscopy and semi-empirical calculations. A resonance dipole–dipole mechanism alone cannot account for the rate of EET in both 1 and 2. It is demonstrated that a superexchange mechanism ia the quinoxaline Troger's base linker is responsible for the enhanced energy transfer rates in these systems. Strong quenching of the fluorescence intensity observed in 3 is interpreted as arising from long-range (>18 A) through-biquinoxalinyl bridge mediated photoinduced electron transfer from the free-base porphyrin to the gold(III) porphyrin. These systems provide useful models for the arrangements of the primary donor–acceptor pair in photosynthetic reaction centres, and for elucidating the role of the connecting bridge in electron and energy transfer processes.

Frequency-upconverted organic crystal

The fluorescent characteristics of Troger's base have been investigated experimentally. A one-photon-induced fluorescent spectrum was observed, and the peak wavelength was at 337 nm with a full width at half-maximum of ~85nm . The violet radiation of the Troger's base crystal could result from the pi(*) -pi transition of the benzenoid pi bond. Two-photon-pumped frequency-upconverted fluorescence was obtained, which is a wideband emission with the main peak wavelength at 337 nm and a subordinate peak. Donor groups and acceptor groups of electrons in the aromatic rings strengthen the two-photon-pumped frequency-upconverted fluorescence.

Molecular recognition: Chain length selectivity studies of dicarboxylic acids by the cavity of a new Troger's base receptor

A new dicarboxylic acid receptor 1 having two pyridinc amide motifs built on a Troger's base spacer has been designed and synthesised. The binding studies are performed with a series of dicarboxylic acids and the cavity of receptor 1 was found to be selective for suberic acid.

Multiple bonds between transition metals and main-group elements, 163 nitrogen-donor adducts of organorhenium(VII) oxides: Structural and catalytic aspects

Abstract N-base adducts of methyltrioxorhenium(VII) (1), characterized by their structural and spectroscopic data, are compared with respect to the influence of the pKb values of the N-bases. The crystal structure of one of these derivatives, namely the adduct of Troger's base ((5R,11R)-(+)−2,8-dimethyl-6H,12H-5,11-methanodibenzo[b,f]-[1,5]diazocine) with compound 1 (2a) is reported. The cell constants are as follows: a = 1281.6(2)pm, b = 833.9(1)pm, c = 1705.5(2)pm, β = 106.09(1)°, V = 1751.2(4) × 106 pm3. Derivative 2a exhibits the longest Re(VII)-N bond distance known to date. Furthermore, 2a is the first adduct of Troger's base whose structure has been examined by X-ray crystallography. Epoxidation and sulfoxidation catalysis with N-base adducts of 1 is described, the influence of the Re-N bond strength on the catalytic processes is discussed.