Functionalized 3,3′,5,5′‐Tetraaryl‐1,1′‐Biphenyls: Novel Platforms for Molecular Receptors
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This paper describes the development of novel aromatic platforms for supramolecular construction. By the Suzuki cross-coupling protocol, a variety of functionalized m-terphenyl derivatives were prepared (Schemes 1–4). Macrolactamization of bis(ammonium salt) (S,S)-6 with bis(acyl halide) 7 afforded the macrocyclic receptor (S,S)-2 (Scheme 1), which was shown by 1H-NMR titration studies to form ‘nesting' complexes of moderate stability (Ka between 130 and 290 M−1, 300 K) with octyl glucosides 13–15 (Fig. 2) in the noncompetitive solvent CDCl3. Suzuki cross-coupling starting from 3,3′,5,5′-tetrabromo-1,1′-biphenyl provided access to a novel series of extended aromatic platforms (Scheme 5) for cleft-type (Fig. 1) and macrotricyclic receptors such as (S,S,S,S)-1. Although mass-spectral evidence for the formation of (S,S,S,S)-1 by macrolactamization between the two functionalized 3,3′,5,5′-tetraaryl-1,1′-biphenyl derivatives (S,S)-33 and 36 was obtained, the 1H- and 13C-NMR spectra of purified material remained rather inconclusive with respect to both purity and constitution. The versatile access to the novel, differentially functionalized 3,3′,5,5′-tetrabromo-1,1′-biphenyl platforms should ensure their wide use in future supramolecular construction.