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A New Family of C 3 ‐Symmetrical Carbohydrate Receptors
Author(s) -
Welti Roger,
Diederich François
Publication year - 2003
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200390049
Subject(s) - chemistry , sonogashira coupling , benzene , stereochemistry , yield (engineering) , monosaccharide , tris , receptor , crystallography , palladium , organic chemistry , catalysis , biochemistry , materials science , metallurgy
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.