New macrocyclic molecules are described containing two or three p-tert-butylcalix[4]arene subunits connected via their oxygen atoms. These macrocycles are available by two general methods which are capable of producing assemblies with bridges of varying rigidity and length

Böhmer, Volker

Kraft, Dagmar

Loon, Jan-Dirk van

McKervey, M. Anthony

Owens, Michael

Reinhoudt, David N.

Verboom, Willem

Vogt, Walter

English

van Loon, Jan-Dirk

Reinhoudt, David

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Double and triple calix[4]arenis connected via the oxygen functions

Dagmar Kraft

Jan-Dirk van Loon

Michael Owens

Willem Verboom

Walter Vogt

M.Anthony McKervey

Volker Böhmer

David N. Reinhoudt

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Tetrahedron Letters

University of Twente Research Information

Temhcdmn Lmm. VoL31. No.34. pi 49414944.1~ Rhtcd in Great Brimin oo4O4039/90 s3.oo+JM Pcrgmcm Press pk DOUBLE AND TRIPLE CALIX[4]ARXNES CONNECTBD VIA THE OXYGEN FUNCTIONS Dagmar KrafP, Jan-Dirk van Loonb, Michael Owens=, Willem Ver- boomb, Walter Vogta, M. Anthony McICervey*C, Volker BLihmer*a, David N. Reinhoudt*b 6 Institute of Organic Chemistry, University of Mainz, 6500 Mainz, West Germany bDepartment of Organic Chemistry, University of Twente, 7500 A6 Enschede, The Netherlands CDepartment of Chemistry, University College Cork, Ireland Abstract: New macrocyclic molecules are described containing two or three p-tert-butylcalixC4Iarene subunits connected via their oxygen atoms. These macrocycles are available by two general methods which are capable of producing assemblies with bridges of varying rigidity and length. Recent work by several groups has established that calix[rl]- arenes are useful molecular substructures on which to assemble collections of covalently bound functional groups capable of ac- ting as ligating podands in ion or molecule receptors'. The majo- rity of such chemically modified calix[4larenes exist in the cone conformation which confers on the receptor a considerable degree of preorganisation. p-tert-Butylcalix[Q]arene 1 is now so readily accessible2 that this member of the series is being increasingly used as a building block for larger, more elaborate molecular as- semblies. Our interest in larger systems includes the synthesis of double and triple calixarenes possessing well defined molecular cavities and clefts capable of selective receptor activity. One approach to such systems requires the regioselective modi- fication or further functionalization of the phenolic groups in 1. 1 2 4941 4942 Diametrically (1,3-j functionalized calix[llarenes, i.e. l,J-de- rivatives of type 2, have been synthesized by several groups in good to excellent yieldsa. Suitable (sufficiently flexible) di- functional reagents may then lead to bridging of the molecule4. We wished to build up macrocyclic assemblies in which two ca- lix[l]arene subunits are connected via two bridges between their respective oxygen atoms at the l- and 3-positions. One way of a- chieving this goal was to use a difunctional reagent, e.g. a di- acid dichloride, which is too rigid to make an intramolecular bridging of the calixlllarene possible. 3 b: X= f? w c: x- CH /C\wn/CH2-c~NH/C\cH 2 2 4 When terephthaloyl chloride (1 mmol in 50 ml of THF) was added at 4OoC over a period of 15 h to a solution of 1 (1 mm01 in 200 ml of benzene/acetonitrile = l/l) in the presence of RzCOa after purification by flash chromatography double calixarene 3a, mp. r3000C was isolated in 33% yield. In contrast, use of isophthalic acid dichloride with 1 under various conditions gave no identificable products. 4943 The distance between the calixarene moieties in 3a can be var- ied by varying the length of the bridging difunctional reagents. Thus, the biphenyl-containing double calixarene 3b, mp. +3OOQC, could be obtained in 32% yield from 1 (1 mm01 in 200 ml of THF) and KOtBu (2 mmol) after adding the appropriate diacid dichloride (1 mm01 in 50 ml of THF) over 18 h under refluxs. Interestingly, reduction of the addition time to 9 h in the synthesis of 3b caused the yield to decrease to 15%, but led to the triply inter-bridged triscalixarene or "triple calixarene" 4, mp. 28OoC (decomp.), in 18% yield. To the best of our knowledge 4 is the first example of a molecule in which three calix[l]arene moieties are connected by three bridges. An alternative strategy to obtain doubly bridged double calix- arene+ consists of fixing activated functional groups at the l- and 3-positions of calixarene 1. Thus the known diester 2a, ob- tained from 1 and ethyl bromoacetate, could be hydrolysed to di- acid 2b and transformed into diacid dichloride 2c by the action of thionyl chloride. 3c was prepared by adding 2c and ethylenediamine (each 2.3 mm01 in 100 ml of dry benzene) at room temperature si- multaneously in a dropwise fashion to a stirred solution of tri- ethylamine (7.2 mmol) in 100 ml of dry benzene. After 24 h the reaction mixture afforded after purification by chromatography and recrystallization from methanol/CHnClz 16% of 3c, mp. 320-322oC (decomp.). Other diamines may be used as bridging reagents in a similar way, These new double and triple calixarenes were charac- terised by microanalysis and FAB mass spectrometry. Their struc- tures are supported by IH- and 13C-NMR data. Table 1 summarizes the 'H-NMR data of compounds 3 and 4. The differences in chemical shift found for the t-butyl and aromatic protons reflect the different types of bridging. Table 1. 1 H-NMR data ( d-values in ppm, 200 MHz. CDClo I Compound Calix Bridge ArH OH ArCHaAr (J, Hz) t-Bu ArH (J,Hz) 3a 6.93 4.68 3.50 (14.4) 6.99 3.90 (14.4) 3b 6.80 4.85 3.48 (14.1) 7.12 4.26 (14.1) 3ca 7.04 8.28 3.45 (13.2) 4.12 (13.2) 4 a.= 7.03 5.61 3.30 (13.71 7.04 4.11 (13.7) 1.05 8.41 1.17 0.91 1.30 1.13 1.22 7.72 (8.4) 8.26 (8.3) Bridge-datab 1.11 7.99 (8.6) 1.23 8.17 (8.5) *) 400 MHz; b) NH: 8.56, OCH,: 3.65 broad, (CHn)z: 4.51; ') CDoClo These new bridged calix[4]arenes may form the basis for highly organised molecular receptors with well defined cavity dimensions. Furthermore the remaining hydroxyl groups in 3 or 4 should be amenable to further chemical modification with ligating functional groups. Alternatively they could be used to insert additional bridges, thereby producing a new series of polyfunctional and highly organised calixcryptands and calixsperands. Acknowledgements. This investigation was supported by the EC Twinning Project Nr. ST2J-0215. We also acknowledge J. M. Visser, J. L. M. Vrielink and A. Vierengel for recording the NMR spectra, and T. W. Stevens for recording the FAB mass spectra. References and notes. r11 121 131 F. Arnaud-Neu, E. M. Collins, M. Deasy, G. Ferguson, S. J. Harris, B. Kaitner, A. J. Lough, M. A. McKervey, E. Marques, B. H. Ruhl, M. J. Schwing-Weill, E. M. Seward, J. Am. Chem. Sot. 111, 1989, 8687 and references cited there. For the preparation of t_butylcalix[4]arene see: C. D. Gutsche et al. Org. Syn th. in press: for reviews on calixarenes see C. D. Gutsche Top. Curr. Chem. 133, 1984, 1; C. D. Gutsche "Calixarenes", Vol. 1 in "Monographs in Supramolecular Chemis- try", Editor J. F. Stoddart, The Royal Society of Chemistry, 1989. a) R. Ungaro, A. Pochini, G. D. Andreetti, J. Incl. Phenom. 2, 1984, 199. b) E. M. Collins, M. A. McKervey, S. J. Harris, J. Chem. Sot., Perkin Trans. 1, 1989, 372. c) C. D. Gutsche, M. Iqbal, K. S. Nam, K. See, I. Alam, Pure & Appl. Chem. 60, 1988, 483; see already C. D. Gutsche, B. Dha- wan, J. A. Levine, K. Ii. No, L. J. Bauer. Tetrahedron 39, [aI I51 [61 1983, 409. d) J.-D. van Loon, A. Arduini, W. Verboom, R. Ungaro, G. J. van Hummel, S. Harkema, D. N. Reinhoudt, Tetrahedron Lett. 30, 1989, 2681. e) D. N. Reinhoudt, P. J. Dijkstra, P. J. A. in't Veld, K. E. Buoge, S. Harkema, R. Ungaro, E. Ghidini, J. Am. Chem. Sot. 103, i987, 4761. f) P. J. Dijkstra, J. A. J. Brunink, K. E. Bugge, D. N. Rein- houdt, S. Harkema, R. Ungaro, F. Ugozzoli, E. Ghidini, J. Am. Chem. Sot. 111, 1989, 7567. J.-D. van Loon, D. Kraft, M. J. K. Ankone, W. Verboom, S. Harkema. V. Behmer, W. Vogt, D. N. Reinhoudt, J. Org. Chem., in press and references cited there. Double calixarenes of type 3 were also obtained as by-products in the bridging of 1 with the 3.3'-disulfonylchloride of ben- zophenone and of diphenylsulfoxide'. Similar double calixarenes with a single bridge connecting the phenolic oxygens have been recently prepared: M. A. McKervey. M. Owens, H.-R. Schulten, W. Vogt, V. BGhmer, Angew. Chem. 102, 1990, 280. (Received in UK 11 June 1590) 

Double and triple calix[4]arenis connected via the oxygen functions

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