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Abstract:
As water‐soluble macrocyclic host for apolar guest molecules, the tetraoxa[7.1.7.1]paracyclophane 1 was synthesized. In the key reaction of the synthesis, two equivalents of 1‐acetyl‐4,4‐bis(4‐hydroxy‐3,5‐dimethylphenyl)piperidine (4) and two equivalents of 1‐acetyl‐4,4‐bis[2‐(p‐tolylsulfonyl)ethyl]piperidine (8) were cyclized to the tetraoxa[7.1.7.1]paracyclophane 9. The synthesis of 8 starting from 1‐acetyl‐4‐piperidone is described. 1 was obtained following the reaction sequence 9 → 10 → 11 → 2 → 1. The temperature dependency of the 1H NMR spectra of 1 is discussed. –1H NMR studies of host‐guest interactions in aqueous solutions between 1 and aromatic guest molecules bearing cationic residues and between 1 and alicyclic guest molecules are described. The association constants Ka (1 · mol−1) of the complexes were either determined by solid‐liquid extraction and from competitive inhibition experiments, or estimated from NMR complexation shifts Δδ.
