Benzo crown-6, synthesis

Accordingly, iV-phenyl-substituted isothiazolium salts bearing a benzo crown ether substituent were employed in this synthetic protocol and led to the synthesis of various crown ether-substituted 6aA4-thia-l,6-diazapentalenes 201... 

Engle, N.L., Bonnesen, P.V., Tomkins, B.A., Haverlock, T.J., Moyer, B.A. 2004. Synthesis and properties of calix[4]arene-bis[4-(2-ethylhexyl)benzo-crown-6], a cesium extractant with improved solubility. Solvent Extr. Ion Exch. 22 (4) 611-636. 

A number of reports [10, 17, 22, 25-27] suggest that, in the case of condensation between aromatic diols and polyethylene glycols, the nature of the template exerts an influence on the rate of macrocyclisation. The templates form various series depending on the size of the synthesised crown ether, but lithium ion is an inhibitor in all cases. This must be attributed to the fact that Li+ forms the most stable ion pair with phenolate and simultaneously gives the least stable complexes with benzo crown ethers. It should be noted that alkaline earth metal ions, even in small concentrations, promote these reaction more effectively than alkali metal ions. In addition, it has been emphasised [12] that there is a definite correlation between the basicity of the substance used in the template synthesis of macrocyclic polyethers and the yield of final product. 

We have previously described the synthesis of calixcrowns by one-pot reactions. In a different approach the calix(aza)crowns were constructed by stepwise synthesis. The synthesis began with the condensation of cone-1,3-dialdehyde derivative 16 with various primary diamines to afford Schiff base-p-terr-butylcalix[4]arenes 17-20 in the cone conformation [29, 30]. Hydrogenation of 18 and 19 with NaBHt produced chlorohydrates 21HC1 and 22-HCl and subsequent deprotonation with NaOH lead to the di-aza-benzo-crown-ether-/j-tert-butylcalix[4]arenes 21 and 22 in almost quantitative yield [31] (Figure 6). 

Diederich F, Jonas U, Gramlich V, Herrmann A, Ringsdorf H and Thilgen C 1993 Synthesis of a fullerene derivative of benzo[18]crown-6 by Diels-Alder reaction complexation ability, amphiphilic properties, and x-ray crystal structure of a dimethoxy-1,9-(methano[1, 2]benzomethano)fullerene[60] benzene clathrate Helv. Chim. Acta 76 2445-53... 

H-Benzo[a]carbazole, 4,4a,5,l 1,1 la,l Ib-hexahydro-synthesis, 4, 283 Benzo[b]carbazole, N-acetyl-photochemical rearrangements, 4, 204 Benzo[/]chroman-4-one, 9-hydroxy-2,2-dimethyl-synthesis, 3, 851 Benzochromanones synthesis, 3, 850, 851, 855 Benzochromones synthesis, 3, 821 Benzocinnoline-N-imide ring expansion, 7, 255 Benzocinnolines synthesis, 2, 69, 75 UV, 2, 127 Benzocoumarins synthesis, 3, 810 Benzo[15]crown-5 potassium complex crystal stmcture, 7, 735 sodium complex crystal stmcture, 7, 735 Benzo[ 18]cr own-6 membrane transport and, 7, 756 Benzo[b]cyclohepta[d]furans synthesis, 4, 106 Benzocycloheptathi azoles synthesis, 5, 120... 

The first method is shown in Eq. (3.1). This corresponds to the so-called one plus one synthesis of crowns. The notion is that a single diol unit is allowed to react with a single polyethylene glycol having leaving groups at each end. An example of this would be the synthesis of benzo-15-crown-5 from catechol and tetraethylene glycol dichloride. Note that the stoichiometry of this method is identical to that of method X which is shown below in Eq. (3.3). 

When K.yba, Cram and coworkers attempted the synthesis of dibinaphthyl-22-crown-6 from binaphthol and diethylene glycol ditosylate. the reagent ratio was as described either by V or X (Eqs. 3.1 or 3.3). The intent was to make the 22-membered ring. Some of the 11-membered ring was isolated as well (Eq. 3.5). None was apparently observed for the benzo case because the nine-membered ring is less favorable. In short, it is not the intent of the synthesis but the reaction dynamics which determine the product. 

Synthesis and Characterization of N-[l,10-Phenanthroline]-N -[(Benzo-15-Crown-5)yl] Thionrea and Its Complex with Copper(I)... 

The use of metals for prearranging reaction centers as neighboring groups has a special value in the production of macrocycles (template effect). Although these ligands can be sometimes prepared directly, the addition of metal ion during the synthesis will often increase the yield, modify the stereochemical nature of the product, or even be essential in the buildup of the macrocycle. There have been few mechanistic studies of these processes. The alkali and alkaline-earth metal ions can promote the formation of benzo[18]crown-6 in methanol ... 

The incoiporation of two asymmetric precursors into chiral crown ethers with C2 symmetiy must be carried out with total constitutional and stereochemical control during the reaction sequence. This has been accomplished elegantly during the synthesis of the three chiral benzo-15-crown-5 derivatives (SS)-79, and (5S)- 0 from (S)-lactic acid (122, 123). 

Synthesis of C-Tennmal Modified Benzo-15-crown-5 PolvfL-GlutOBzl)] 19 ... 

One of the first published examples (Scheme 10) was the modified polymethacrylate poly(17) obtained from monomer 17 containing a benzo[15] crown-5 unit and a biphenyl linked via an ester group [34], The synthesis was... 

Figure 3.45 shows the results of kinetic studies of the template synthesis of benzo [18] crown-6 according to the reaction shown, as a function of the templating cation. Clear rate enhancements... 

Fedorova, O.A., Maurel, Fr., Ushakov, E.N., Nazarov, V.B., Gromov, S.P., Chebun kova, A.V., Feofanov, A.V., Alaverdian, I.S., Alfimov, M.V., Barigelletti, Fr. (2003) Synthesis, photochromic behaviour and light-controlled complexation of 3,3-diphenyl-3//-benzo[/]chromenes containing a dimethylamino group or an aza-15-crown-5 ether unit, New J. Chem., 27, 1155-1167. 

Liu, Y., Zhang, H. Y., Bai, X. P., Wada, T., and Inoue, Y. (2000) Molecular design of crown ethers. 21. Synthesis of novel double-armed benzo-15-crown-5 lariats and their complexation thermodynamics with light lanthanoid nitrates in acetonitrile, J. Org. Chem. 65, 7105-7109 see also Danil de Namor, A. F. D., Chahine, S., Jafou, O., and Baron, K. (2003) Solution thermodynamics of lanthanide-cryptand 222 complexation processes, J. Coord. Chem 56, 1245-1255 Israeli, Y., Bonal, C., Detellier, C., Morel, J. P., and Morel-Desrosiers, N. (2002) Complexation of the La(III) cation by p-sulfonatocalix[4]arene - A La-139 NMR study, Canad. J. Chem. 80, 163-168. 

Fig. 3 (A) Distribution scheme for template-directed synthesis of benzo-18-crown-6.53 (B) Thermodynamic cycle analysis can be used for...

Synthesis of Double-decker Lutetium(lll) Diphthalocyanine with Crown-Ether Substituents b/s tetra[(benzo-15-crown-5)-4 -yl-oxymethyl]phthalocyaninato lutetium(lll) [118d]... 

The applicability of cesium fluoride for the synthesis of smaller crown ether rings such as benzo[12]crown-4 (35) was investigated by Bartsch et al. [45]. The result of this study was that the 12-membered crown ether 35 and its naphthalene analogue 36 can be obtained from the aromatic diols 33 and the tosylate 34 with the base cesium fluoride in yields of 29 and 25 %, respectively. This means a significant increase in the 4% yield of benzo[12]crown-4 (35) reported by Pedersen, who started with sodium phenolate [38]. 

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