ChemInform Abstract: Alkylation of Benzo and Dibenzo Crown Ethers with Different Alcohols.

2009

Chem Heterocycl Comp

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The sulfonation of monosubstituted derivatives of dibenzo-18-crown-6 with potassium sulfate in polyphosphoric acid has been carried out. Sulfonic acids with various functional groups in the second nucleus of dibenzo-18-crown-6 have been obtained. A qualitative comparison of the reactivity of the substrates gave information on the transfer of the electronic influence of a substituent through the macrocycles. The displacement of electron density in the benzene nuclei of the substrates and the products of sulfonation was assessed from the value of the displacement of the proton signals in the 1 H NMR spectra. acid, PPA (polyphosphoric acid), potassium sulfate, sulfonation.Derivatives of dibenzo-18-crown-6 (DB18C6) in which substitution is only in one benzene nucleus, are of considerable interest as substrates for carrying out electrophilic substitution reactions. These reactions open a route to disubstituted compounds with mixed functions which, as is evident from literature data [1], relate to few studied substances. At the same time the presence of two benzene nuclei with different functional groups makes these derivatives extremely promising substances for subsequent directed modification as a result of conversions of the functional groups. Study of electrophilic substitution of the hydrogen atoms of the unsubstituted benzene nucleus in monosubstituted derivatives of DB18C6 is also of considerable theoretical interest, since comparison of the reactivity of substrates with substituents of different electronic effect enables clarification of the influence of a substituent from the substituted nucleus on the unsubstituted through the macrocycle, which was called by us a "transannular transfer" [2].An investigation was carried out previously of nitration reactions of ethyl-, nitro-, and acetyl-DB18C6 with nitrates of certain alkali metals in PPA. It was demonstrated that the nitration reaction proceeds regioselectively and depends on the nature of the substituent and the metal cation [3].

“…Mp 163-164°C. Starting materials were obtained by methods developed in [4][5][6]. The 1 H NMR spectra of initial and final compounds are given in Table 1.…”

Section: Methodsmentioning

confidence: 99%

Sulfonation of 4′-acetyl-, 4′-(tert-butyl)-dibenzo-18-crown-6 and (dibenzo-18-crown-6)-4′-sulfonic acid with potassium sulfate in polyphosphoric acid

Grebenyuk

2009

Chem Heterocycl Comp

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“…Composition of the reaction mixture was controlled by TLC on Merck plates with 1:20:20:1 hexane-chloroform-acetoneethanol as solvent. The starting materials 2a-d were synthesized as we described previously [4]. Compounds 2e,f,g were prepared by the methods of papers [6][7][8] respectively.…”

Section: Methodsmentioning

confidence: 99%

“…It is carried out in the presence of HCl, polyphosphoric acid, or polyphosphoric acid ester or by simply fusing the reagents together [1-3]. We chose as the carbonyl compound 4',4"(5")-diacetyl-DB-18-C6 (2a), which we had synthesized earlier [4], since its condensation with the diamine 1 should permit preparation of the required product in a single step. We did not succeed in carrying out the reaction of diamine 1 with the diacetyl derivative in the presence of the condensing agents mentioned above.…”

mentioning

confidence: 99%

Synthesis of Bis(2,2-benzimidazolyl)dibenzo-18-crown-6

Saifullina

Galieva

2005

Chem Heterocycl Compd

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A method has been developed for the introduction of benzimidazole substituents into the dibenzo-18-crown-6 molecule by condensation of its 4',4"(5")-diacetyl derivative with ortho-phenylenediamine. Increasing the length of the hydrocarbon chain of the acyl substituent or replacing Ac by CSNH 2 led to a decrease in the yield of the desired product. No product was formed when Ac was replaced by COOH or CN.

“…The structure of these isomers was established earlier [5]. Acylation with lithium and potassium acetates gives a product mostly containing the 4',4"-isomer 1, whereas acylation with sodium acetate leads to a mixture of isomers 1 and 2 with a wider melting range.…”

mentioning

confidence: 87%

“…This product melts at 196-200°C, indicating that it is mainly the 4',4"-isomer 1 (mp of isomer 1 197-199°C, mp of 4',5"-isomer 2 213-215°C [5]). It was found that the length of the process and the composition of the reaction products, according to data from TLC, depend on the cation.…”

mentioning

confidence: 99%

Acylation of Dibenzo-18-crown-6 with Alkali-metal Acetates in Polyphosphoric Acid

Saifullina

2005

Chem Heterocycl Compd

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