✍ Scribed by Roger Welti; François Diederich
No coin nor oath required. For personal study only.
The formation of the new optically active C~3~‐symmetrical receptors (S,S,S)‐2–4 (Fig. 1), incorporating 1,3,5‐triphenylbenzene and 1,3,5‐tris(phenylethynyl)benzene platforms as ‘floors' and ‘ceilings', is described. The tris(phenylethynyl)benzene derivatives 9 and (S,S,S)‐10 (Scheme 1) for the three‐fold peptide coupling to yield the macrocyclic skeletons (Scheme 2) were prepared starting from 1,3,5‐triethynylbenzene by the Sonogashira cross‐coupling reaction. The optical rotations of the three macrocycles (S,S,S)‐2–4, two of which ((S,S,S)‐2 and (S,S,S)‐3) are constitutional isomers, differ significantly, which is explained by differential twists induced into the macrocyclic skeletons by the leucine spacer in these bridges. 1 : 1 Host–guest complexes of (S,S,S)‐2–4 with octyl glucosides (Fig. 3) in CDCl~3~ are of modest stability (K~a~≤270 M^−1^ at 300 K). In these complexes, the monosaccharides are most probably nesting on one of the H‐bonding faces of the receptor rather than being accommodated in the cavity.
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