Trogers Bases

Troger s bases constitute a relatively simple but geometrically rich, V-shaped dass of bicyclic molecules that are commonly formed under acid catalysis by the simple condensation of anilines and formaldehyde. They have found a variety of applications, such as their use as relatively rigid chiral frameworks for the construction of chelating and biomimetic systems [71]. 

In general, it is now accepted that the mechanism for the formation of Trbger s bases involves a series oiin-situ Friedel-Crafts reactions of 125, butthe detailed course of the reaction has not yet been fully established. In trying to elucidate major mechanistic aspects, different methylene sources as well as different anilines have 

On the basis of the mechanistic data collected from on-line ESI-MS(/MS) monitoring and the gas-phase ion/molecule reactions just described, an experimentally probed mechanism for the formation of Troger s bases using either formaldehyde or. 

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Fig. la-e. Examples of frequently used building blocks for synthetic host molecules a calixarene b cyclotriveratrylene c resorcinol-aldehyde tetramer d Kemps triacid e Trogers base... 

The pretzel-shaped molecule 96 (the first pretzelane ) was synthesized by intramolecular bridging of the two sulfonamide units of 79 with a bifunctionalized podand-like chain [54]. Again the enantioseparation of 96 was accomplished with a baseline quality separation and a large separation factor (a=5.20). Preparative separation of the enantiomers enabled the detection of the circular dichrogram of 96 (Figure 48). The optical rotation values of 79 and 96 were both determined to be [aD] = 168° (Troger base [aD] = 281°). 

Capillaries packed with poly-A-acryloyl-L-phenylalanine ethyl ester (Chiraspher) modified silica were used for electrochromatographic enantiomer separation of ben-droflumethiazide. To suppress bubble formation, the inlet buffer vial was pressurized to 12 bar and the outlet buffer vial to 4 bar [42], Acetonitrile or methanol were used as organic modifier whereby acetonitrile was superior to methanol. Non-aqueous p-CEC was performed on helical poly(diphenyl-2-pyridylmethylmethacrylate) coated on wide-pore aminopropyl silica [56]. With this chiral stationary phase, the enantiomer separation of Trogers base, benzoin acetate, methylbenzoin and trans-stilbene oxide was achieved by pressure-supported CEC, applying a higher pressure to the inlet than to the outlet buffer vial. 

Instead, a tweezer shape was shown by the bis-Troger base skeleton of 18 with the aromatic arms lying almost parallel with each other (23.1°), with a distance between its centroids of 4.368(5) A. The central phenyl ring is almost orthogonal to the external aromatic arms (a, 79.3° b, 88.6°). The molecular packing showed that in the c-direction every two molecules are intercalated each other in such a way that, in the case of 18a, the nitro arm of one molecule is... 

UV-Vis absorption and fluorescence emission of Troger base analogue 51 and its precursor 2-(4-amino-2-hydro-xyphenyl)benzothiazole were measured. In the UV-Vis spectra, all molar extinction coefficient values were in the order of 104lmol 1 cm as expected for 71-71 transitions. 

Ishida Y., Ito H., Mori D., Saigo K. (2005) Regio/diastereo-controls of the Bingel-type biscyclopropanation of [60]fullerene by using bismalonates with a Troger base analogue-derived tether, Tetrahedron letters, 46, 109-112. 

Figure 3.48 Comparison of the purchased and cleaned Troger base mixtures. Analytical injection at wavelength of 308 nm (a) and 315 nm (b). Solid lines, original sample dashed lines, sample purified by crystallization dotted lines, sample purified by preparative HPLC separation on a Cis-bonded silica. Reproduced with permission from K, Mihlbachler, K. Kaczmarski, A. Seidel-Morgenstern, G. Guiochon, J. Chromatogr. A, 955 (2002) 35 (Fig. 4).

Figure 4.12 Competitive isotherms of the (-)- and (+)- enantiomers of Troger base on microcrystalline cellulose triacetate, with ethanol as mobile phase, (a) Single-component adsorption isotherm of (+)-TB (squares) and (-)-TB (triangles) at 40° C. Experimental data and best fit to a Langmuir, (+)-TB, and a quadratic, (-)-TB, isotherm model, (b) Competitive isotherms of (-)-TB in enantiomeric mixtures for increasing concentrations (0, 0.5,1,1.5,2, 2.5, 3 g/L) of (+)-TB, calculated with IAS theory, (c) Competitive isotherms of (+)-TB in enantiomeric mixtures for increasing concentrations (0, 0.5, 1, 1.5, 2, 2.5, 3 g/L) of (-)-TB calculated with IAS theory. Reproduced from A. Seidel-Morgenstem and G. Guiockon, Chem. Eng. Sci., 48 (1993) 2787 (Figs. 4, 6, and7).

Lenev, D.A. Lyssenko, K.A. Kostyanovsky, R.G. Asymmetric nitrogen 82. Troger base Study of its complex with HgBr2 and its methiodide. Russ. Chem. Bull. (Transl. from Izvestija Akad. Nauk. SSSR, Ser. Khim.) 2000 49. 1241-1249. 

Bond. D.R. Scott. J.L. Clathrate formation with Troger base analogs. J. Chem. Soc.. Perkin Trans., II 1991. 47-51. 

Weber. E. Muller. U. Worsch, D. Vogtle, F. Will, 6. Kirfel. A. Quaternary Troger bases as new inclusion hosts The first x-ray structures of a Triiger base and of a dioxane clathrate. J. Chem. Soc.. Chem. Commun. 1985. 1578-1580. 

In the last decades, NMR has evolved as one of the methods used for the determination of chiral species. Among recent examples, chiral hexacoordinated phosphate anion, [bis(tetrachlorobenzenediolato)mono ([l,r]binaphtalenyl-2,2 -diolato)phosphate], (d,i )-BINPHAT (52), as its tetrabutylammonium salt, has found widespread use as a very efficient NMR chiral solvating agent (CSA) for quaternary ammonium cations (quats) derived from a Troger base (53) (Figure 5). ... 

Scheme 7.86 Enantioselective aziridination of chalcones catalyzed by Troger base.

SYNTHESIS OF MACROCYCLES HAVING TROGER BASE SKELETONS "[2.2]CYCLIC TROGER BASE" ... 

ABSTRACT [2.23Cyclic Troger base 2 was synthesized by the condensation of 1,2-bis(4-aminophenyl)ethane with paraformaldehyde under acidic condition in 43.8% yield. [2.2]Cyclic Troger base 2 was separated into meso form and racemate by fractional crystallization or using HPLC. Resolution of the racemate into its optical antipodes by passing the racemate throu an activated D-(+)-lactose column was partially succeeded. 

With the hope of obtaining such macrocycles, we tried to synthesize macrocyclic compounds having Troger base skeletons as chiral host molecules. ... 

Wieland This was the first classical demonstration that optical activity was due to an asymmetric trivalent nitrogen atom. Cyclophanes 2 in Fig. 1 consisting of two Troger base skeletons... 

SYNTHESIS OF MACROCYCLES HAVING TROGER BASE SKELETONS... 

CycIic Troger base 2 was obtained by the condensation of 1,2-bis(4-aminophenyl)ethane with paraformaldehyde under acidic condition in one step in unexpectedly high yield as shown in Scheme 1. 

According to the combination of (1R 5R)- and (IS 5S)-Troger base units as shown in Fig. 1, there exist three possible isomers namely, the meso form (IR 5R,1 S 5 S)cyclic Troger base, and optically active forms (IR 5R,1 R 5 R)- and (IS 5S,1 S 5 S)cyclic Troger base. The separation of [2.2]cyclic Troger base 2 into the meso form and the racemate was accomplished by repeated fractional recrystallization from 2-propanol and CH Cl or preparative HPLC. The racemate was... 

This synthetic method has been successfully applied to other systems, such as [1.1]- (<10% yield) and [3.3]cyclic Troger base (13% yield). In order to make these macrocycles flexible, further studies on the synthesis of several derivatives of 2 are in progress. 

The resolution of racemic [2.2]cyclic Troger base 2b was performed... 

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