Selective Monofunctionalization of Tri-urea-mono-acetamides of ­Calix[4]arenes on the Narrow Rim

Abstract

The synthesis of calix[4]arenes substituted at their wide rim by three 3-aryl-urea and one acetamide group and at their narrow rim by three alkyl ether groups and one ether group ending in a carboxy function is described. The reaction sequence ensures that these functional groups are attached to the same phenolic unit. Two key intermediates have been additionally characterized by X-ray crystal structure analysis.

Key words

calixarenes - alkylations - carboxylic acids - self-assembly - supramolecular chemistry

References

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1

Permanent address: Institute of Organic Chemistry, NAS of Ukraine, Murmanska str. 5, Kyiv-94, 02094 Ukraine.

2

For X-ray crystal structure analysis.

6

For self-sorting see: Braekers, D.; Peters, C.; Bogdan, A.; Rudzevich, Y.; Böhmer, V.; Desreux, J. F. J. Org. Chem. 2008, 73, 701.

11

Also both positions might be functionalized, while the introduction of four functional groups (requiring no selectivity) most probably leads to sterical crowding, which would prevent the formation of dendrimers.

13

To use calix[4]arenes as universal building blocks, it would be ideal to functionalize all four positions at the wide rim (the p-positions of the phenolic units) and at the narrow rim (the four phenolic OH functions) selectively and independently.

17

X-ray crystallographic data for 4: C₅₃H₇₁NO₈·C₂H₃N M = 891.16 g·mol^-1, colorless block, size 0.52 × 0.41 × 0.26 mm³, monoclinic, space group P2₁/n, a = 18.4285 (13), b = 24.673 (2), c = 23.6687 (17) Å, β = 101.889 (6), V = 10531.0(14) ų, T = -100 °C, Z = 8, ρ_calcd = 1.124 g·cm^-3, µ (Mo-Kα) = 0.074 mm^-1, F(000) = 3856, 66424 reflections in h(-21/22), k(-29/29), l(-28/26), measured in the range 2.56° £ Θ £ 25.39°, completeness Θ_max = 98.3%, 19049 independent reflections, R _int = 0.0889, 8537 reflections with F _o > 4σ(F _o), 1229 parameters, 0 restraints, R1_obs = 0.0676, wR2_obs = 0.1603, R1_all = 0.1406, wR2_all = 0.1890, GOOF = 0.850, largest difference peak and hole: 0.928/-0.363 e·Å^-3.

18

X-ray crystallographic data for 6: C₅₁H₆₉NO₅·2 C₂H₆OS, M = 932.33 g·mol^-1, colorless rod, size 0.27 × 0.14 × 0.13 mm³, triclinic, space group P-1, a = 12.3270 (8), b = 21.5880 (11), c = 22.6254 (12) Å, α = 65.959 (4), β = 83.687 (5), γ = 80.551 (5)°, V = 5417.9 (5) ų, T = -100 °C, Z = 4, ρ_calcd = 1.143 g·cm^-3, µ (Mo-Kα) = 0.147 mm^-1, F(000) = 2024, 52650 reflections in h(-14/12), k(-25/25), l(-26/26), measured in the range 3.35° £ Θ £ 25.03°, completeness Θ_max = 99.4%, 19028 independent reflections, R _int = 0.0624, 12643 reflections with F _o > 4σ(F _o), 1263 parameters, 60 restraints, R1_obs = 0.0895, wR2_obs = 0.2316, R1_all = 0.1274, wR2_all = 0.2585, GOOF = 1.047, largest difference peak and hole: 1.318/-1.408 e·Å^-3.

22

SHELXL-97 (Release 97-2), Sheldrick, G. M., University of Göttingen: Germany, 1997.

23

CCDC 662358 (4) and CCDC 662359 (6) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: [phone]; email: [e-mail]).