From four-fold functionalised [3.3]cyclophanes to belt-shaped and multibridged molecules

Abstract

Reaction of the four-fold functionalised cyclophane 7 with tetrafunctionalised aromatic building blocks such as 9 and 10 afforded the new belt-shaped molecules 3 and 4, respectively. The new four-fold bridged cyclophane 8 was synthesised by cyclisation of 7 with tosylamide monosodium salt. The macropolycycle 5, the structure of which has been confirmed by single crystal X-ray analysis, was obtained by cyclisation of the first tetrafunctionalised biphenylophane 15 with the tetrathiol 16. The constitution and conformation of compounds 3, 5 and 8 were examined by VT-NMR studies and HH-NOE experiments. Crystallisation of 8 from two different solvents leads to guest-dependent conformational changes revealed by X-ray analysis. The results described demonstrate that molecular belts and tubes of different type and size are accessible by varying the building blocks within our synthetic strategy.