Premium
Macrocyclic Hexaureas: Synthesis, Conformation, and Anion Binding
Author(s) -
Meshcheryakov Denys,
Böhmer Volker,
Bolte Michael,
HubscherBruder Véronique,
ArnaudNeu Françoise
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200802573
Subject(s) - chemistry , molecule , monomer , intramolecular force , hydrogen bond , ether , diamine , amine gas treating , proton nmr , polymer chemistry , xanthene , condensation reaction , medicinal chemistry , stereochemistry , photochemistry , organic chemistry , catalysis , polymer
Varied flexibility : Cyclic oligoureas are formed by using anions as templates. Linking of six xanthene and/or diphenyl ether fragments by urea groups leads to the formation of five macrocyclic compounds with a 48‐membered ring with variable flexibility (see picture). Their interaction with anions shows a strong influence of acetate and chloride ions on the cyclization from four precursor molecules.Five macrocylic compounds , XXDXXD, XDXDXD, XDDXDD, and with 48‐membered rings, in which six xanthene and/or diphenyl ether fragments are linked through six urea (‐NH‐C(O)‐NH‐) groups, have been synthesized. In the cyclization step, a linear diamine was allowed to react with the appropriate diisocyanate by using a [5+1] (i.e., “XDXDX+D” for XDXDXD), [4+2] (), or [3+3] (XDDXDD) procedure. Compounds and XXDXXD were prepared from two molecules of the dimeric amine XX and two molecules of the respective monomeric diisocyanate (X or D) in a [2+1+2+1] (or 2×[2+1]) reaction. The (nonoptimized) yields in the cyclization step ranged from 45 to 80 %. The linear precursor diamines or diisocyanates were obtained by analogous condensation reactions by using partial protection with a tert ‐butoxycarbonyl group. All the macrocyclic compounds and synthetic intermediates were characterized by 1 H NMR and mass spectra. Three different crystal structures were obtained for XDDXDD, which show the molecule in a more or less strongly folded conformation determined by intramolecular hydrogen bonding. The interaction of the hexaureas with selected anions was studied by 1 H NMR spectroscopy and UV absorption spectrophotometry.