- Email: [email protected]
Upper rim substitution of thiacalix[4]arene
TETRAHEDRON LETTERS Pergamon
Tetrahedron Letters 42 (2001) 7107–7110
Upper rim substitution of thiacalix[4]arene Pavel Lhota´k,a,* Michal Himl,a Ivan Stibor,a Jan Sykorab and Ivana Cisarova´c a
Department of Organic Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6, Czech Republic Department of Solid State Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6, Czech Republic c Department of Inorganic Chemistry, Charles University, Hlavova 8, 128 43, Prague 2, Czech Republic
b
Received 11 June 2001; revised 30 July 2001; accepted 7 August 2001
Abstract—Upper rim bromination of thiacalix[4]arene has been achieved for the first time using a distally disubstituted thiacalix[4]arene as a starting material. Depending on the bromine:thiacalix[4]arene ratios, the corresponding dibromo- and tetrabromo derivatives were obtained which opens the door for subsequent derivatisation of the upper rim of thiacalix[4]arenes. Interestingly, direct bromination of tetraalkylated compounds did not yield brominated derivatives. The structure of the tetrabromo derivative in the 1,3 -alternate conformation was proven by X-ray crystallography. © 2001 Elsevier Science Ltd. All rights reserved.
Thiacalix[4]arenes1 1 and 2 represent new members of a well-known calixarene family.2,3 The presence of four sulfur atoms instead of methylene groups imposes many new properties on the thiacalix[4]arene skeleton when compared with the chemistry of ‘classical’ calixarenes. Very recently, several interesting reactions,4,5 unknown in classical calix[4]arene chemistry, have been described. Similarly, the oxidation of sulfur to sulfoxide6 or sulfone7 derivatives offers many possible applications. This makes thiacalixarenes very attractive candidates for use as molecular scaffolds or as building blocks in the synthesis of more sophisticated systems. Unfortunately, the employment of thiacalixarenes in supramolecular chemistry is still rather restricted by the relatively unknown chemistry of these compounds and the lack of general derivatisation methods.
Until now, only one example of upper rim derivatisation of a thiacalixarene has been described. The ipsosulfonation of 2 with concentrated sulfuric acid gives
* Corresponding author. Tel.: +420-2-2435 4280; fax: +420-2-2435 4288; e-mail: [email protected]
the corresponding tetrasulfonated derivative in good yield.8 During our studies on the electrophilic substitution of thiacalix[4]arenes, we have found that the reactivity of this new system is very different from that of calix[4]arene. Thus, all our attempts at the nitration, halogenation, Friedel–Crafts acylation or formylation using procedures known in classical calixarene chemistry have failed. In this paper we report on the first direct bromination of the thiacalix[4]arene upper rim which opens the door for the subsequent derivatisation of these compounds. Bromosubstituted thiacalixarenes would represent extremely useful intermediates with many possible synthetic applications (e.g. substitution with CN− or preparation of organometallic derivatives). Accordingly, we have studied the bromination of 1 and 3, using the conditions2,3,9 known in classical calix[4]arene chemistry: (i) Br2/CHCl3; (ii) NBS/2–butanone or (iii) Br2/ Fe. Unfortunately, all our attempts failed. In the most cases, only unreacted starting compounds were isolated or the bromination yielded very complex reaction mixtures, from which we could not identify the expected products. A similar situation was found during the bromination of tetrapropoxy thiacalix[4]arene (1,3 alternate) 4, which was prepared by the alkylation of 1 with PrI/K2CO3 in boiling acetone.10 Hence, we have directed our attention to the bromination of dialkylated compounds, where one can envisage the possible formation of distal dibromo derivatives. The bromination of 25,27-dipropoxythiacalix[4]arene 511 was carried out by the addition of Br2 (3 equiv.) to
0040-4039/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII: S 0 0 4 0 - 4 0 3 9 ( 0 1 ) 0 1 4 6 1 - 7
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a chloroform solution of the compound, followed by stirring at room temperature for 24 h (Scheme 1). The 1 H NMR analysis of the reaction mixture proved the presence of mono- and di-substituted products, together with a small amount of unreacted starting compound. The use of excess amounts of bromine (6 equiv.) finally led to the successful isolation of the dibromo derivative 6 in 73% yield. Identical reaction conditions12 with 12 equiv. of bromine gave, smoothly, tetrabromo derivative 7 (90%). This seems to be particularly unpredictable in the light of our above-mentioned unsuccessful attempts. The structures of both compounds were proven by 1H NMR. Compound 6 possesses a triplet (6.60 ppm, J=7.7 Hz) and a doublet (6.97 ppm, J=7.7 Hz) corresponding to the unsubstituted phenyl rings, together with two singlets from the substituted rings (7.75 ppm) and from the hydroxyl groups (7.53 ppm). We could not prepare suitable crystals for the X-ray analysis of 6. Due to the stronger electron-donating effects of free OH groups, it seems feasible to assume that substitution takes place preferentially on the nonalkylated phenolic rings. The conformational assignment of thiacalix[4]arene derivatives is not a trivial task due to the absence of CH2 bridges, the signals of which are used in classical calix[4]arene stereochemical assignments. The above splitting pattern indicates that 6 prefers to adopt either an 1,3 -alternate or a cone conformation in CDCl3 solution. Differential 1 H NMR NOE experiments revealed that both derivatives adopt cone conformations, held together by intramolecular hydrogen bond arrays. Tetrabromo derivative 7 was treated with propyl iodide in boiling acetone in the presence of potassium carbonate to yield tetraalkylated products. As found by NMR analysis, the reaction mixture contained 1,3 -alternate 8 and partial cone 9 conformers13 in the approximate ratio of 3:1 (56%) which were separable by crystallisa-
tion from acetone. Surprisingly, alkylation carried out using PrI/NaH in DMF at room temperature (conditions yielding the cone conformation in calix[4]arene chemistry2,3) led to a mixture of the same products 8 and 9 in a molar ratio of 1:2 (73%). The absence of the cone conformer in the reaction mixture indicates different conformational preferences, again demonstrating the distinction between the classical and thiacalixarene series. Hence, both tetrabromo substituted tetraalkylated conformations (partial cone or 1,3 -alternate) are easily accessible as starting compounds for subsequent derivatisations. While the structure of partial cone derivative 9 was assigned using 1H NMR spectroscopy (as expected two doublets with meta coupling and two singlets in the aromatic region), the potential cone structure of 8 was ruled out by means of NOE 1H NMR spectra (through space contacts between aromatic protons and propyl groups). The conformation of 8 was unequivocally proven by X-ray crystallography.14 Suitable single crystals were grown by slow evaporation of the solvent (ethyl acetate). Compound 8 in a 1,3 -alternate conformation represents a relatively symmetrical molecule, however, it crystallises in triclinic form, space group P1( . Moreover, five symmetrically independent molecules A–E form the independent part of the cell (Fig. 1). Thus, the elementary cell is created by ten molecules. The aromatic units are highly distorted from an ideal S4 geometry. The angles between the main plane defined by the four sulfur atoms and aromatic units range from 80 to 130°. The average distance between two neighbouring sulfur atoms in 8 is 5.56 A, (Fig. 2). It demonstrates that the size of the cavity in thiacalix[4]arene is approximately 0.5 A, bigger than that in classical calix[4]arene. In conclusion, contrary to tetraalkoxythiacalix[4]arenes, 25,27-dialkoxythiacalix[4]arenes were found to undergo
Scheme 1. (i) PrI/K2CO3 (1 equiv.), acetone, reflux (66%); (ii) PrI/K2CO3 (10 equiv.), acetone, reflux (51%); (iii) Br2 (6 equiv.)/CHCl3, rt (73%); (iv) Br2 (12 equiv.)/CHCl3, rt (90%); (v) PrI/K2CO3, acetone, 48 h, reflux (56%); (vi) PrI/NaH, DMF, 48 rt (73%).
P. Lhota´ k et al. / Tetrahedron Letters 42 (2001) 7107–7110
Figure 1. Five molecules of 8 creating the independent part of an elementary cell.
Figure 2. ORTEP drawing of the X-ray structure of 8 (molecule B).
electrophilic bromination of the upper rim yielding the corresponding dibromo or tetrabromo substituted thiacalixarene derivatives. This substitution opens the door for subsequent transformation of thiacalixarenes and, hence, for their use as building blocks in the synthesis of more elaborate structures.
Acknowledgements We thank the Grant Agency of the Czech Republic for financial support for this work (GA 104/00/1722 and GA 203/99/1163).
References 1. Kumagai, H.; Hasegawa, M.; Miyanari, S.; Sugawa, Y.; Sato, Y.; Hori, T.; Ueda, S.; Kamiyama, H.; Miyano, S. Tetrahedron Lett. 1997, 38, 3971–3972.
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2. For books on calixarenes, see: (a) Calixarenes 2001 ; Asfari, Z.; Bo¨ hmer, V.; Harrowfield, J.; Vicens, J., Eds.; Kluwer Academic Publishers: Dordrecht, 2001; (b) Gutsche, C. D. Calixarenes Revisited: Monographs in Supramolecular Chemistry; Stoddart, J. F., Ed.; The Royal Society of Chemistry: Cambridge, 1998; Vol. 6; (c) Calixarenes 50th Anniversary: Commemorative Issue; Vicens, J.; Asfari, Z.; Harrowfield, J. M., Eds.; Kluwer Academic Publishers: Dordrecht, 1994; (d) Calixarenes: A Versatile Class of Macrocyclic Compounds; Vicens, J.; Bo¨ hmer, V., Eds.; Kluwer Academic Publishers: Dordrecht, 1991. 3. For recent reviews on calixarenes, see: (a) Ikeda, A.; Shinkai, S. Chem. Rev. 1997, 97, 1713–1734; (b) Bo¨ hmer, V. Angew. Chem., Int. Ed. Engl. 1995, 34, 713–745. 4. Lhota´ k, P.; Dudic, M.; Stibor, I.; Petrickova, H.; Sykora, J.; Hodacova, J. Chem. Commun. 2001, 731–732. 5. Katagiri, H.; Iki, N.; Hattori, T.; Kabuto, C.; Miyano, S. J. Am. Chem. Soc. 2001, 123, 779–780. 6. (a) Iki, N.; Narumi, F.; Fujimoto, T.; Morohashi, N.; Miyano, V. J. Chem. Soc., Perkin Trans. 2 1998, 2745; (b) Mislin, G.; Graf, E.; Hosseini, M. W.; DeCian, A.; Fischer, J. Tetrahedron Lett. 1999, 40, 1129–1132. 7. Mislin, G.; Graf, E.; Hosseini, M. W.; DeCian, A.; Fischer, J. Chem. Commun. 1998, 1345–1346. 8. Iki, N.; Fujimoto, T.; Miyano, S. Chem. Lett. 1998, 625–626. 9. (a) Wong, M. S.; Li, Z. H.; Kwok, C. C. Tetrahedron Lett. 2000, 41, 5719–5724; (b) Larsen, M.; Jorgensen, M. J. Org. Chem. 1996, 61, 6651–6655. 10. Lhota´ k, P.; Himl, M.; Pakhomova, S.; Stibor, I. Tetrahedron Lett. 1998, 39, 8915–8918. 11. Lhota´ k, P.; Kapla´ nek, L.; Stibor, I.; Lang, J.; Dvora´ kova´ , H.; Hrabal, R.; Sy´ kora, J. Tetrahedron Lett. 2000, 41, 9339–9344. 12. General procedure for the bromination of 5: A solution of bromine in 10 ml of CHCl3 was added dropwise to a solution of compound 5 (100 mg, 0.172 mmol) in 20 ml of CHCl3 and the reaction mixture stirred at room temperature for 24 h. The excess bromine was removed by extraction with an aqueous Na2S2O3 solution, the organic layer was washed with water, dried with MgSO4 and evaporated to half volume. The addition of methanol yielded the product as a white solid that was dried over night at 80°C. Compound 6: used 6 equiv. of Br2 (73%). Mp 254–256°C (acetone). 1H NMR (CDCl3): l 1.13 (t, 6H, J=7.7 Hz, -CH3), 2.00 (m, 4H, -CH2-CH3), 4.27 (t, 4H, J=6.7 Hz, OCH2CH2), 6.60 (t, 2H, J=7.7 Hz, H-arom), 6.97 (d, 4H, J=7.7 Hz, H-arom), 7.53 (s, 2H, OH), 7.75 (s, 4H, H-arom). EA calcd for C30H26Br2O4S4: C, 48.79; H, 3.55; S, 17.36; Found: C, 48.31; H, 3.76; S, 17.44. Compound 7: used 12 equiv. of Br2 (90%). Mp 301–303°C (acetone). 1H NMR (CDCl3): l 1.14 (t, 6H, J=6.8 Hz, -CH3), 2.00 (m, 4H, -CH2-CH3), 4.27 (t, 4H, J=7.6 Hz, OCH2CH2), 7.13 (s, 4H, H-arom), 7.56 (s, 2H, OH), 7.76 (s, 4H, H-arom). EA calcd for C30H24Br4O4S4: C, 40.20; H, 2.70; Br, 35.66; Found: C, 40.46; H, 3.05; Br, 35.27. FAB MS m/z (rel. int.) 896.0 [M]+ (100). 13. Compound 8: Mp >350°C (acetone). 1H NMR (CDCl3, 300 MHz): l 0.77 (t, 12H, J=7.7 Hz, -CH2-CH3), 1.35 (m, 8H, -CH2-CH3), 3.88 (t, 8H, J=7.1 Hz, -O-CH2-), 7.51 (s, 8H, H-arom). Compound 9: Mp 332–334°C (acetone). 1H NMR (CDCl3): l 0.77 (t, 3H, J=7.7 Hz,
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-CH2-CH3), 1.15 (m, 11H, -CH2-CH3+-CH2-CH3), 1.88 (m, 4H, -CH2-CH3), 2.09 (m, 2H, -CH2-CH3), 3.60 (m, 4H, -O-CH2-), 4.10 (m, 4H, -O-CH2-), 7.01 (d, 2H, J=2.3 Hz, H-arom), 7.68 (d, 2H, J=2.2 Hz, H-arom), 7.69 (s, 2H, H-arom), 7.20 (s, 2H, H-arom). 14. X-Ray data for 8: C36H36Br4O4S4, M=980.56 g/mol, triclinic system, space group P1( , a=17.393(1), b= 23.964(1), c=27.422(1) A, , h=106.94(1), i=100.56(1), k=102.23(1)°, Z=10, V=9881.6(1) A, 3, Dcalcd=1.65 g cm−3, v(Cu Ka)=4.32 mm−1, crystal dimensions of 0.5× 0.15×0.05 mm. Data were measured at 150(2) K on an Nonius Kappa CCD diffractometer with graphite monochromated Mo Ka radiation.15 The structure was solved by direct methods.16 The bromine, sulfur and oxygen atoms were refined anisotropically, carbon atoms only isotropically by full-matrix least-squares on F values.17 Distances between carbon atoms in the propoxy group were restrained to a value of 1.54(1) A, . Hydrogen atoms were located from expected geometry. This model converged to final R=0.0842 and Rw=0.0529 using 14979 independent reflections (qmax=23°). Gaussian was
15. 16.
17.
18.
used for the absorption correction.18 Crystallographic data (excluding structure factors) for the structures in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication numbers CCDC 164981. Copies of the data can be obtained, free of charge, on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax: +44 (0) 1223–336033 or e-mail: [email protected]]. Hooft, R. W. Collect. Nonius BV, Delft, The Netherlands, 1998. Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.; Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna, R. J. Appl. Cryst. 1999, 32, 115– 119. Watkin, D. J.; Prout, C. K.; Carruthers, R. J.; Betteridge, P. Crystals Issue 10, Chemical Crystallography Laboratory: Oxford, UK, 1996. Coppens, P. Crystallographic Computing; Ahmed, F. R.; Hall, S. R.; Huber, C. P., Eds.; Munksgaard: Copenhagen, 1970; pp. 255–270.
Tetrahedron Letters 42 (2001) 7107–7110
Upper rim substitution of thiacalix[4]arene Pavel Lhota´k,a,* Michal Himl,a Ivan Stibor,a Jan Sykorab and Ivana Cisarova´c a
Department of Organic Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6, Czech Republic Department of Solid State Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6, Czech Republic c Department of Inorganic Chemistry, Charles University, Hlavova 8, 128 43, Prague 2, Czech Republic
b
Received 11 June 2001; revised 30 July 2001; accepted 7 August 2001
Abstract—Upper rim bromination of thiacalix[4]arene has been achieved for the first time using a distally disubstituted thiacalix[4]arene as a starting material. Depending on the bromine:thiacalix[4]arene ratios, the corresponding dibromo- and tetrabromo derivatives were obtained which opens the door for subsequent derivatisation of the upper rim of thiacalix[4]arenes. Interestingly, direct bromination of tetraalkylated compounds did not yield brominated derivatives. The structure of the tetrabromo derivative in the 1,3 -alternate conformation was proven by X-ray crystallography. © 2001 Elsevier Science Ltd. All rights reserved.
Thiacalix[4]arenes1 1 and 2 represent new members of a well-known calixarene family.2,3 The presence of four sulfur atoms instead of methylene groups imposes many new properties on the thiacalix[4]arene skeleton when compared with the chemistry of ‘classical’ calixarenes. Very recently, several interesting reactions,4,5 unknown in classical calix[4]arene chemistry, have been described. Similarly, the oxidation of sulfur to sulfoxide6 or sulfone7 derivatives offers many possible applications. This makes thiacalixarenes very attractive candidates for use as molecular scaffolds or as building blocks in the synthesis of more sophisticated systems. Unfortunately, the employment of thiacalixarenes in supramolecular chemistry is still rather restricted by the relatively unknown chemistry of these compounds and the lack of general derivatisation methods.
Until now, only one example of upper rim derivatisation of a thiacalixarene has been described. The ipsosulfonation of 2 with concentrated sulfuric acid gives
* Corresponding author. Tel.: +420-2-2435 4280; fax: +420-2-2435 4288; e-mail: [email protected]
the corresponding tetrasulfonated derivative in good yield.8 During our studies on the electrophilic substitution of thiacalix[4]arenes, we have found that the reactivity of this new system is very different from that of calix[4]arene. Thus, all our attempts at the nitration, halogenation, Friedel–Crafts acylation or formylation using procedures known in classical calixarene chemistry have failed. In this paper we report on the first direct bromination of the thiacalix[4]arene upper rim which opens the door for the subsequent derivatisation of these compounds. Bromosubstituted thiacalixarenes would represent extremely useful intermediates with many possible synthetic applications (e.g. substitution with CN− or preparation of organometallic derivatives). Accordingly, we have studied the bromination of 1 and 3, using the conditions2,3,9 known in classical calix[4]arene chemistry: (i) Br2/CHCl3; (ii) NBS/2–butanone or (iii) Br2/ Fe. Unfortunately, all our attempts failed. In the most cases, only unreacted starting compounds were isolated or the bromination yielded very complex reaction mixtures, from which we could not identify the expected products. A similar situation was found during the bromination of tetrapropoxy thiacalix[4]arene (1,3 alternate) 4, which was prepared by the alkylation of 1 with PrI/K2CO3 in boiling acetone.10 Hence, we have directed our attention to the bromination of dialkylated compounds, where one can envisage the possible formation of distal dibromo derivatives. The bromination of 25,27-dipropoxythiacalix[4]arene 511 was carried out by the addition of Br2 (3 equiv.) to
0040-4039/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII: S 0 0 4 0 - 4 0 3 9 ( 0 1 ) 0 1 4 6 1 - 7
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a chloroform solution of the compound, followed by stirring at room temperature for 24 h (Scheme 1). The 1 H NMR analysis of the reaction mixture proved the presence of mono- and di-substituted products, together with a small amount of unreacted starting compound. The use of excess amounts of bromine (6 equiv.) finally led to the successful isolation of the dibromo derivative 6 in 73% yield. Identical reaction conditions12 with 12 equiv. of bromine gave, smoothly, tetrabromo derivative 7 (90%). This seems to be particularly unpredictable in the light of our above-mentioned unsuccessful attempts. The structures of both compounds were proven by 1H NMR. Compound 6 possesses a triplet (6.60 ppm, J=7.7 Hz) and a doublet (6.97 ppm, J=7.7 Hz) corresponding to the unsubstituted phenyl rings, together with two singlets from the substituted rings (7.75 ppm) and from the hydroxyl groups (7.53 ppm). We could not prepare suitable crystals for the X-ray analysis of 6. Due to the stronger electron-donating effects of free OH groups, it seems feasible to assume that substitution takes place preferentially on the nonalkylated phenolic rings. The conformational assignment of thiacalix[4]arene derivatives is not a trivial task due to the absence of CH2 bridges, the signals of which are used in classical calix[4]arene stereochemical assignments. The above splitting pattern indicates that 6 prefers to adopt either an 1,3 -alternate or a cone conformation in CDCl3 solution. Differential 1 H NMR NOE experiments revealed that both derivatives adopt cone conformations, held together by intramolecular hydrogen bond arrays. Tetrabromo derivative 7 was treated with propyl iodide in boiling acetone in the presence of potassium carbonate to yield tetraalkylated products. As found by NMR analysis, the reaction mixture contained 1,3 -alternate 8 and partial cone 9 conformers13 in the approximate ratio of 3:1 (56%) which were separable by crystallisa-
tion from acetone. Surprisingly, alkylation carried out using PrI/NaH in DMF at room temperature (conditions yielding the cone conformation in calix[4]arene chemistry2,3) led to a mixture of the same products 8 and 9 in a molar ratio of 1:2 (73%). The absence of the cone conformer in the reaction mixture indicates different conformational preferences, again demonstrating the distinction between the classical and thiacalixarene series. Hence, both tetrabromo substituted tetraalkylated conformations (partial cone or 1,3 -alternate) are easily accessible as starting compounds for subsequent derivatisations. While the structure of partial cone derivative 9 was assigned using 1H NMR spectroscopy (as expected two doublets with meta coupling and two singlets in the aromatic region), the potential cone structure of 8 was ruled out by means of NOE 1H NMR spectra (through space contacts between aromatic protons and propyl groups). The conformation of 8 was unequivocally proven by X-ray crystallography.14 Suitable single crystals were grown by slow evaporation of the solvent (ethyl acetate). Compound 8 in a 1,3 -alternate conformation represents a relatively symmetrical molecule, however, it crystallises in triclinic form, space group P1( . Moreover, five symmetrically independent molecules A–E form the independent part of the cell (Fig. 1). Thus, the elementary cell is created by ten molecules. The aromatic units are highly distorted from an ideal S4 geometry. The angles between the main plane defined by the four sulfur atoms and aromatic units range from 80 to 130°. The average distance between two neighbouring sulfur atoms in 8 is 5.56 A, (Fig. 2). It demonstrates that the size of the cavity in thiacalix[4]arene is approximately 0.5 A, bigger than that in classical calix[4]arene. In conclusion, contrary to tetraalkoxythiacalix[4]arenes, 25,27-dialkoxythiacalix[4]arenes were found to undergo
Scheme 1. (i) PrI/K2CO3 (1 equiv.), acetone, reflux (66%); (ii) PrI/K2CO3 (10 equiv.), acetone, reflux (51%); (iii) Br2 (6 equiv.)/CHCl3, rt (73%); (iv) Br2 (12 equiv.)/CHCl3, rt (90%); (v) PrI/K2CO3, acetone, 48 h, reflux (56%); (vi) PrI/NaH, DMF, 48 rt (73%).
P. Lhota´ k et al. / Tetrahedron Letters 42 (2001) 7107–7110
Figure 1. Five molecules of 8 creating the independent part of an elementary cell.
Figure 2. ORTEP drawing of the X-ray structure of 8 (molecule B).
electrophilic bromination of the upper rim yielding the corresponding dibromo or tetrabromo substituted thiacalixarene derivatives. This substitution opens the door for subsequent transformation of thiacalixarenes and, hence, for their use as building blocks in the synthesis of more elaborate structures.
Acknowledgements We thank the Grant Agency of the Czech Republic for financial support for this work (GA 104/00/1722 and GA 203/99/1163).
References 1. Kumagai, H.; Hasegawa, M.; Miyanari, S.; Sugawa, Y.; Sato, Y.; Hori, T.; Ueda, S.; Kamiyama, H.; Miyano, S. Tetrahedron Lett. 1997, 38, 3971–3972.
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2. For books on calixarenes, see: (a) Calixarenes 2001 ; Asfari, Z.; Bo¨ hmer, V.; Harrowfield, J.; Vicens, J., Eds.; Kluwer Academic Publishers: Dordrecht, 2001; (b) Gutsche, C. D. Calixarenes Revisited: Monographs in Supramolecular Chemistry; Stoddart, J. F., Ed.; The Royal Society of Chemistry: Cambridge, 1998; Vol. 6; (c) Calixarenes 50th Anniversary: Commemorative Issue; Vicens, J.; Asfari, Z.; Harrowfield, J. M., Eds.; Kluwer Academic Publishers: Dordrecht, 1994; (d) Calixarenes: A Versatile Class of Macrocyclic Compounds; Vicens, J.; Bo¨ hmer, V., Eds.; Kluwer Academic Publishers: Dordrecht, 1991. 3. For recent reviews on calixarenes, see: (a) Ikeda, A.; Shinkai, S. Chem. Rev. 1997, 97, 1713–1734; (b) Bo¨ hmer, V. Angew. Chem., Int. Ed. Engl. 1995, 34, 713–745. 4. Lhota´ k, P.; Dudic, M.; Stibor, I.; Petrickova, H.; Sykora, J.; Hodacova, J. Chem. Commun. 2001, 731–732. 5. Katagiri, H.; Iki, N.; Hattori, T.; Kabuto, C.; Miyano, S. J. Am. Chem. Soc. 2001, 123, 779–780. 6. (a) Iki, N.; Narumi, F.; Fujimoto, T.; Morohashi, N.; Miyano, V. J. Chem. Soc., Perkin Trans. 2 1998, 2745; (b) Mislin, G.; Graf, E.; Hosseini, M. W.; DeCian, A.; Fischer, J. Tetrahedron Lett. 1999, 40, 1129–1132. 7. Mislin, G.; Graf, E.; Hosseini, M. W.; DeCian, A.; Fischer, J. Chem. Commun. 1998, 1345–1346. 8. Iki, N.; Fujimoto, T.; Miyano, S. Chem. Lett. 1998, 625–626. 9. (a) Wong, M. S.; Li, Z. H.; Kwok, C. C. Tetrahedron Lett. 2000, 41, 5719–5724; (b) Larsen, M.; Jorgensen, M. J. Org. Chem. 1996, 61, 6651–6655. 10. Lhota´ k, P.; Himl, M.; Pakhomova, S.; Stibor, I. Tetrahedron Lett. 1998, 39, 8915–8918. 11. Lhota´ k, P.; Kapla´ nek, L.; Stibor, I.; Lang, J.; Dvora´ kova´ , H.; Hrabal, R.; Sy´ kora, J. Tetrahedron Lett. 2000, 41, 9339–9344. 12. General procedure for the bromination of 5: A solution of bromine in 10 ml of CHCl3 was added dropwise to a solution of compound 5 (100 mg, 0.172 mmol) in 20 ml of CHCl3 and the reaction mixture stirred at room temperature for 24 h. The excess bromine was removed by extraction with an aqueous Na2S2O3 solution, the organic layer was washed with water, dried with MgSO4 and evaporated to half volume. The addition of methanol yielded the product as a white solid that was dried over night at 80°C. Compound 6: used 6 equiv. of Br2 (73%). Mp 254–256°C (acetone). 1H NMR (CDCl3): l 1.13 (t, 6H, J=7.7 Hz, -CH3), 2.00 (m, 4H, -CH2-CH3), 4.27 (t, 4H, J=6.7 Hz, OCH2CH2), 6.60 (t, 2H, J=7.7 Hz, H-arom), 6.97 (d, 4H, J=7.7 Hz, H-arom), 7.53 (s, 2H, OH), 7.75 (s, 4H, H-arom). EA calcd for C30H26Br2O4S4: C, 48.79; H, 3.55; S, 17.36; Found: C, 48.31; H, 3.76; S, 17.44. Compound 7: used 12 equiv. of Br2 (90%). Mp 301–303°C (acetone). 1H NMR (CDCl3): l 1.14 (t, 6H, J=6.8 Hz, -CH3), 2.00 (m, 4H, -CH2-CH3), 4.27 (t, 4H, J=7.6 Hz, OCH2CH2), 7.13 (s, 4H, H-arom), 7.56 (s, 2H, OH), 7.76 (s, 4H, H-arom). EA calcd for C30H24Br4O4S4: C, 40.20; H, 2.70; Br, 35.66; Found: C, 40.46; H, 3.05; Br, 35.27. FAB MS m/z (rel. int.) 896.0 [M]+ (100). 13. Compound 8: Mp >350°C (acetone). 1H NMR (CDCl3, 300 MHz): l 0.77 (t, 12H, J=7.7 Hz, -CH2-CH3), 1.35 (m, 8H, -CH2-CH3), 3.88 (t, 8H, J=7.1 Hz, -O-CH2-), 7.51 (s, 8H, H-arom). Compound 9: Mp 332–334°C (acetone). 1H NMR (CDCl3): l 0.77 (t, 3H, J=7.7 Hz,
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-CH2-CH3), 1.15 (m, 11H, -CH2-CH3+-CH2-CH3), 1.88 (m, 4H, -CH2-CH3), 2.09 (m, 2H, -CH2-CH3), 3.60 (m, 4H, -O-CH2-), 4.10 (m, 4H, -O-CH2-), 7.01 (d, 2H, J=2.3 Hz, H-arom), 7.68 (d, 2H, J=2.2 Hz, H-arom), 7.69 (s, 2H, H-arom), 7.20 (s, 2H, H-arom). 14. X-Ray data for 8: C36H36Br4O4S4, M=980.56 g/mol, triclinic system, space group P1( , a=17.393(1), b= 23.964(1), c=27.422(1) A, , h=106.94(1), i=100.56(1), k=102.23(1)°, Z=10, V=9881.6(1) A, 3, Dcalcd=1.65 g cm−3, v(Cu Ka)=4.32 mm−1, crystal dimensions of 0.5× 0.15×0.05 mm. Data were measured at 150(2) K on an Nonius Kappa CCD diffractometer with graphite monochromated Mo Ka radiation.15 The structure was solved by direct methods.16 The bromine, sulfur and oxygen atoms were refined anisotropically, carbon atoms only isotropically by full-matrix least-squares on F values.17 Distances between carbon atoms in the propoxy group were restrained to a value of 1.54(1) A, . Hydrogen atoms were located from expected geometry. This model converged to final R=0.0842 and Rw=0.0529 using 14979 independent reflections (qmax=23°). Gaussian was
15. 16.
17.
18.
used for the absorption correction.18 Crystallographic data (excluding structure factors) for the structures in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication numbers CCDC 164981. Copies of the data can be obtained, free of charge, on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax: +44 (0) 1223–336033 or e-mail: [email protected]]. Hooft, R. W. Collect. Nonius BV, Delft, The Netherlands, 1998. Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano, G. L.; Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori, G.; Spagna, R. J. Appl. Cryst. 1999, 32, 115– 119. Watkin, D. J.; Prout, C. K.; Carruthers, R. J.; Betteridge, P. Crystals Issue 10, Chemical Crystallography Laboratory: Oxford, UK, 1996. Coppens, P. Crystallographic Computing; Ahmed, F. R.; Hall, S. R.; Huber, C. P., Eds.; Munksgaard: Copenhagen, 1970; pp. 255–270.