Skip to main content
  • Preliminary communication
  • Open access
  • Published:

Synthesis and crystal structure of 1,4,10,13-tetraoxa-7,16-diazoniumcyclo-octadecane bis(4-chloro-2-methyl-phenoxyacetate)

Abstract

The title compound was prepared by the reaction of 1,4,10,13-tetraoxa-7,16-diazacyclo-octadecane with 4-chloro-2-methyl-phenoxyacetic acid in a ratio of 1:2. The structure has been proved by the data of elemental analysis, IR spectroscopy, NMR (1H, 13C) technique and by X-ray diffraction analysis. Intermolecular hydrogen bonds between the azonium protons and oxygen atoms of the carboxylate groups were found. Immunoactive properties of the title compound have been screened. The compound has the ability to suppress spontaneous and Con A-stimulated cell proliferation in vitro and therefore can be considered as immunodepressant.

Findings

Over many years the complexes of crown ethers (CE) with protonic acids and their metal salts attract the attention of scientific community due to both their peculiar molecular and stereoelectronic structure as well as the possibility of practical application [1, 2]. The CE complexes enhance physiological activity of several chemical compounds. This fact is likely related to the ability of the complexes formed to overpass cellular and hematoorganic barriers. In particular, specific complex-forming properties of CE allow them to be used for the drug design [2].

Recently, we have shown that tris-(2-hydroxyethyl)ammonium salts of organylheteroacetic acids [RYCH2COO] -·[NH(CH2CH2OH)]3+, (R = Ar, Het; Y = O, S, SO2), the cation of which has compact tricyclic atrane (2,8,9-trihydro-prototranic) structure [3], promoting to penetration of a matter through cellular membranes, represent a new class of biologically active compounds [4–9]. For example, tris(2-hydroxyethyl)ammonium salt of 4-chloro-2-methyl-phenoxyacetic acid exhibits adaptogenic, immunomodulating and antitumor properties. Besides, it effectively increases the resistance of animals to microwave electromagnetic radiation [7–9].

To search for new immunoactive congeners of this series, we have synthesized 1,4,10,13-tetraoxa-7,16-diazoniumcyclo-octadecane bis(4-chloro-2-methyl-phenoxyacetate) 1 and studied its immunoactive properties. Compound 1 was prepared in a yield of up to 98% by the reaction of 1,4,10,13-tetraoxa-7,16-diazacyclo-octadecane (1,10-diaza-18-crown-6 ether) with 4-chloro-2-methyl-phenoxyacetic acid in a ratio of 1:2 (Figure 1).

Figure 1
figure 1

Synthesis of the title compound 1.

Compound 1 forms colorless crystals with m.p. 128°C. The structure of 1 has been proved by the data of elemental analysis, IR spectroscopy and NMR (1H, 13C) technique. The IR spectra of 1 show broad vibration bands of ν(NH2+) in the region 2800-2200 cm-1. The stretching vibration bands of the O-C-O fragments of starting CE are high-field shifted from 1120, 1100 and 1067 to 1150-1090 cm-1. In the IR spectrum, the bands of symmetric and asymmetric stretching vibrations of the carboxylate-ion are observed at 1580-1350 cm-1.

The structure of compound 1 was established by crystal structure analysis. Crystal and experimental data are summarized in Table 1. The molecular structure with the atom labeling scheme is given in Figure 2. The packing diagram is shown in Figure 3. Selected bond lengths (Å), bond angles (°) as well as torsion angles (°) are listed in Table 2.

Table 1 Crystal data and details of the structure solution and refinement
Figure 2
figure 2

ORTEP plot of 1, drawn at a 50% probability level, with atom labeling. Symmetry operation: i2-x, 2-y, 2-z.

Figure 3
figure 3

Packing diagram, showing a ribbon structure along b. Symmetry operation: ii2-x, 1-y, 2-z.

Table 2 Selected bond lengths (Å), bond angles (°), and torsion angles (°)

The asymmetric unit of 1 contains a half of the diprotonated 1,10-diazatetraoxa-18-crown-6 moiety and 4-chloro-2-methylphenoxyacetate as anion. The crown ether is centrosymmetric and the second half of the cation is generated by inversion. 4-Chloro-2-methylphenoxyacetic acid is known as herbicide. In this molecule, the benzene ring and the oxoacetic acid side-chain are almost coplanar (CSD-Code CMPHAA) [10]. In contrast to this, in 1 the acetate moiety is torsioned around O1-C7 forming a torsion angle of -79.7(2)°, whereas a torsion angle of only -8.0(1)° was found in the reference compound. Additionally, the distorsion of the exo-C1 ring angles is more pronounced 1: 115.4(1), 124.3(2)°; CMPHAA: 115.8(12), 122.0(13)°). The molecular packing is characterized by hydrogen bonds forming a ribbon-like structure along the crystallographic b axis. The geometry of the hydrogen bonds are given in Table 3.

Table 3 Hydrogen bond geometry (Å, °)

Immunoactive properties of 1 have been screened. For example, the ability to impact on spontaneous and mitogen-stimulated (Con A, Sigma, 2 mkg/ml) proliferation of splenocytes in mice in vitro (antiproliferative properties) have been studied. It has been found that compound 1 exerts a distinct influence on spontaneous and mitogen-stimulated proliferation of splenocytes. The ability to suppress spontaneous (up to 72%) and Con A-stimulated (up to 99%) cell proliferation of spleen in vitro in the dosage of 3-300 mkg/ml allows compound 1 to be considered as immunodepressant.

Experimental

IR spectra were recorded on a Varian 3100 FT- IR75 spectrophotometer. NMR spectra (ppm) were measured on a DPX 400 instrument (400,13 MHz for 1H and 101,62 MHz for 13C) in D2O or methanol D4 at 25°C. Reflections were collected using a STOE Imaging Plate Diffraction System (IPDS-II) at 210 K. The structure was solved by direct methods as implemented in the program SHELXS-97 [11]. The refinement was carried out using SHELXL-97 [12]. All the non-hydrogen atoms were refined anisotropically. The hydrogen atoms were located from the difference Fourier map and refined isotropically. For the visualisation of the structure the graphic programs DIAMOND [13] and ORTEP for Windows [14] were used. CIF data: Additional file 1. CCDC reference number: 812142.

Compound 1 was synthesized in the following manner. To a solution of 4-Cl-2-CH3-C6H3OCH2COOH (4.01 g, 0.02 mol) in MeOH (10 ml), was added dropwise a methanol (10 ml) solution of (CE) (2.62 g, 0.01 mol). The mixture was stirred at 25°C for 12 h. The solvent was distilled in vacuum. The solid residue was repeatedly washed with ether and dried in vacuum to afford colorless powder (6.50 g, 98% yield), soluble in water and alcohol. Crystals suitable for X-ray diffraction were obtained by recrystallyzation of 1 from methanol (20°C). 1H NMR (D2O): 7.11-6.68 (m, 6H, C6H3O); 4.37 (s, 4H, CH2COO); 3.63-3.56 (m, 16H, OCH2, OCH2CH2O); 3.15 (t, 8H, NCH2); 2.13 (s, 6H, C6H3-CH3). 13C NMR (D2O): 176.80 (C=O); 156.04 (C6H4O); 140.87-111.56 (C6H3); 69.42 (OCH2); 66.99 (CH2COO); 65.29 (OCH2CH2O); 47.31 (NCH2); 15.53 (C6H3-CH3). Anal. Calcd. for C30H44Cl2O10N2: C, 54.24; H, 6.63; Cl, 10.68; N, 4.22; Found: C, 54.54; H, 6.60; Cl, 10.68; N, 4.02.

Conclusions

1,4,10,13-Tetraoxa-7,16-diazoniumcyclo-octadecane bis(4-chloro-2-methyl-phenoxyacetate) 1 has been synthesized by the reaction of 1,10-diaza-18-crown-6 ether with 4-chloro-2-methyl-phenoxyacetic acid in a ratio of 1:2 (yield 98%). The structure of 1 has been proved by the data of elemental analysis, IR spectroscopy, NMR (1H, 13C) technique and X-ray diffraction analysis. X-ray diffraction analysis has shown that the crown ether cation is centrosymmetric. The packing is characterized by a ribbon-like structure stabilized by hydrogen bonds. The title compound is a representative of a novel class of physiologically active compounds possessing immunodepressant properties. The investigation of physiological activity of 1 will be conducted in a new future.

References

  1. Hiraoka M: Crown Compounds: Their Characterisistics and Applications. 1982, Amsterdam, Oxford, New York: Els. Scient. Publ. Comp

    Google Scholar 

  2. Bogatskii AV, Nazarov EI, Golovenko NYa: Biological aspects of activity of crown ethers, criptands and their analogs. J of the DI Mendeleev all-union Chem Soc. 1985, 30: 593-599.

    CAS  Google Scholar 

  3. Voronkov MG, Albanov AI, Aksamentova TN, Adamovich SN, Chipanina NN, Mirskov RG, Kochina TA, Vrazhnov DV, Litvinov MYu: Tris(2-hydroxyethyl)ammonium Salts: 2,8,9-Trihydroprotatranes. Russ J Gen Chem. 2009, 79: 2339-2346. 10.1134/S1070363209110097.

    Article  CAS  Google Scholar 

  4. Voronkov MG, Mirskova AN, Levkovskaja GG: Carcinostatic, Protective, and Adaptive Activities of Tris-(2-Hydroxyethyl)Ammonium Salts of Arylheteroacetic Acids. Dokl Biologica Sciences. 2002, 386: 404-406. 10.1023/A:1020797714298.

    Article  CAS  Google Scholar 

  5. Kolesnikova OP, Kudaeva OT, Sukhenko TG, Limonov VL, Kozlov VA, Mirskova AN, Voronkov MG: Trekrezan as a Modulator of Hemato- and Immunopoieses. Dokl Biologica Sciences. 2003, 391: 306-308. 10.1023/A:1025186114079.

    Article  CAS  Google Scholar 

  6. Mirskova AN, Levkovskaja GG, Mirskov RG, Voronkov MG: Hydroxyalkylammonium Salts of Organylsulfanyl(sulfonyl)acetic Acids - New Stimulators of Biological Processes. Russ J Org Chem. 2008, 44: 1478-1485. 10.1134/S1070428008100126.

    Article  CAS  Google Scholar 

  7. Kolesnikova OP, Mirskova AN, Adamovich SN, Mirskov RG, Kudaeva OT, Voronkov MG: Alkanolammonium Salts of o-Cresoxy and p-Chlorocresoxyacetic Acids as Immunopoiesis Modulators and Cytostatics. Dokl Biologica Sciences. 2009, 425: 107-111. 10.1134/S0012496609020070.

    Article  Google Scholar 

  8. Voronkov MG, Sofronov GA, Starchenko DA, Adamovich SN, Mirskova AN: Protective Properties of Chlorocresacine against Adverse Impact of Electromagnetic Radiation. Dokl Biologica Sciences. 2009, 428: 398-402. 10.1134/S0012496609050020.

    Article  CAS  Google Scholar 

  9. Mirskova AN, Adamovich SN, Mirskov RG, Voronkov MG: Tris-(2-hydroxyethyl)ammonium 2-methyl- and 2-methyl-4-chlorophenoxyacetate serve as effective inhibitors of thrombocyte aggregation and antioxidants. Dokl Biologica Sciences (Engl. Transl.). 2010, 433: 244-246.

    Article  CAS  Google Scholar 

  10. Smith G, Kennard CHL: 4-Chloro-2-methylphenoxyacetic acid (MCPA): C9H9ClO3. Cryst Struct Comm. 1981, 10: 295-299.

    CAS  Google Scholar 

  11. Sheldrick GM: SHELXS-97: Program for the Solution of Crystal Structures. 1997, University of Göttingen, Germany

    Google Scholar 

  12. Sheldrick GM: SHELXL-97, Program for the Refinement of Crystal Structures. 1997, University of Göttingen, Germany

    Google Scholar 

  13. Farrugia LJ: ORTEP-3 for Windows - a version of ORTEP-III with a Graphical User Interface (GUI). J Appl Cryst. 1997, 30: 565-

    Article  CAS  Google Scholar 

  14. Brandenburg K: DIAMOND, Version 3.1. 2005, Bonn: Crystal Impact

    Google Scholar 

Download references

Acknowledgements

The authors acknowledge O. P. Kolesnikova for screening of immunoactive properties of compound 1.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Uwe Schilde.

Additional information

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

SNA carried out the synthetic experiments and drafted the manuscript. ANM has formulated the research idea and prepared the manuscript draft version. RGM prepared the manuscript for submission and coordinated final formulation. US collected the X-ray data and performed the structure solution. Authors read and approved the final manuscript.

Electronic supplementary material

Authors’ original submitted files for images

Rights and permissions

Open Access This is an open access article distributed under the terms of the Creative Commons Attribution Noncommercial License ( https://creativecommons.org/licenses/by-nc/2.0 ), which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.

Reprints and permissions

About this article

Cite this article

Adamovich, S.N., Mirskova, A.N., Mirskov, R.G. et al. Synthesis and crystal structure of 1,4,10,13-tetraoxa-7,16-diazoniumcyclo-octadecane bis(4-chloro-2-methyl-phenoxyacetate). Chemistry Central Journal 5, 23 (2011). https://doi.org/10.1186/1752-153X-5-23

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1186/1752-153X-5-23

Keywords