Crown polyether analog

N,N -Bridged benzimidazol-2-ones Crown polyether analogs... 

While the aforementioned lonophores are Streptomyces metabolites, the crown polyethers. the depicted prototype of which is dlcyclohexyl-18-crown-6, are synthetic W. Although they lack the intricate conformations of the natural lonophores arising from multiple asymmetric carbon atoms, their molecular llgeindlng properties are analogous. While they are less efficient ion carriers, their lack of labile linkages confers Increased chemical stability they find extensive use in org inlc synthesis for solubilizing electrolytes, e.g. K " enolates, in nonpolar solvents thereby providing reactive naked anions ( ). 

The first elaboration of crowns deliberately into sulfur-containing analogs seems to have been conducted by Pedersen . The first of these efforts was directed at incorporating sulfur in complexes of macrocyclic polyethers. Inclusion of sulfur as a portion of ring system 5 was also accomplished as shown in Eq. (6.4) and is reported in a patent which issued before the latter, but was actually filed after it. We note... 

The cooperative nature of inhibition in this system is ascribed to halide mediated PEG adsorption that may also involve interactions with the Cu+ reaction intermediate. Indeed, the earliest studies of PEG-C1 inhibition discuss the possible formation of various polyether-cuprous chloride compounds ranging from PEG helically wound around a CuCl core to crown-ether like moieties bound to the copper surface via chloride [233, 234], Analogous arguments of complex formation were made based on experimental measurements of the physical properties of solutions containing a high PEG/Cu+/2+ ratio [239, 240]. 

In 1992 Anelli et al. developed a template synthesis of catenane based on electron donor-acceptor interactions. The synthesis was accomplished by stirring 1 equiv. of bis(pyridinium) salt (92). 2Pp6, 1 equiv. of 1,4-bis(bromomethyl) benzene, and 2.5 equiv. of the bisparaphenylene-34-crown-lO (93) in acetonitrile at room temperature for 48 h the catenane (94) was obtained with a remarkable 70% yield (Equation (6)) <92JA193>. An analogous [2]-catenane was formed with macrocycle (95) <93RTC429>. Polycatenanes were also synthesized <94AG(E)433>. The macrocyclic polyether tris-1,5-naphtho-57-crown-15 (96) was used to form [3]-, [4]-, and [5]-catenanes [Pg.835]

Substances of the amphotericin D (a polyene), polyether (for example crown cyclic ethers), Antamanide (a peptide), and valinomycin (a depsi-peptide) represent structural types capable of complexing with alkali metal ions and thereby promoting their dissolution in fairly nonpolar solvents. Such compounds are known as ion carriers and some display antibiotic properties which may in part reside with activity in natural membranes. In order to evaluate structural changes upon such interesting functions, Gisin and Merri-field have synthesized a cyclododecapeptide (Chart 15) where the D-a-hy-droxyisovaleric acid and L-lactic acid units of valinomycin were replaced respectively with D-Pro and L-Pro. In MeCl-Aq the valinomycin analog was found to exhibit a seven times greater affinity for potassium picrate (to form a 1 1 hydrophobic complex) than that of the parent depsipeptide. 

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