64379-58-4Relevant academic research and scientific papers
Synthesis of macrocyclic polyether-diester compounds using Al2O3/MeSO3H (AMA) as a new reagent
Sharghi, Hashem,Sarvari, Mona Hosseini
, p. 879 - 882 (2007/10/03)
A new simple and convenient method for the synthesis of macrocyclic polyether-diester compounds containing pyridine and phenyl subcyclic units is developed. Various diacids, are selectively esterified in excellent yields by reaction with oligoethylene glycols in the presence of Al2O3/MeSO3H (AMA) as a new reagent without use of any solvents.
Characterization of chiral host-guest complexation in fast atom bombardment mass spectrometry
Pocsfalvi, Gabriella,Liptak, Miklos,Huszthy, Peter,Bradshaw, Jerald S.,Izatt, Reed M.,Vekey, Karoly
, p. 792 - 795 (2007/10/03)
A new method has been developed for the characterization of complexion between host and guest molecules. Adduct formation between chiral crown ethers 1 and 2 and enantiomeric ammonium ions 4 and 5 was examined. The reference compound 3 (achiral host) was chosen to be similar in structure to the chiral crown ethers for quantitative measurements. Our approach is based on a formalism assuming an equilibrium: [chiral host + H]+ + [achiral host + chiral guest]+1 [chiral host + chiral guest]+ + [achiral host + H]+. The equlibrium constant for this process was calculated using the relative peak intensities of the corresponding species in the FAB mass spectra. It was found that these provide significantly better reproducibility and more reliable results than the relative peak intensity method described before (Sawada, M.; et al. J. Am. Chem. Soc. 1992, 114, 4405; 1993, 115, 7381; Org. Mass Spectrom. 1993, 28, 1525).1-3 In the examples studied, the equilibrium constants corresponding to the formation of heterochiral adducts (S,S-R or R,R-S) were higher than those for the formation of homochiral aggregates (S,S-S or R,R-R).
Synthetic Ionophores. Part 4. Phase Transfer-catalysed Synthesis of Pyridine containing Macrocycles and Their Ionophore Character
Singh, Harjit,Kumar, Subodh,Jain, Anupa,Singh, Paramjit
, p. 965 - 968 (2007/10/02)
Phase transfer-catalysed reactions of pyridine-2,6-dicarboxylic acid dichloride and 2,6-dichloropyridine with oligo(ethylene glycols) procide macrocycles in yields higher than those reported by high dilution or transesterification methods.Extraction and transport studies of some of these macrocycles towards picrates of Li+, Na+, Tl+, Mg2+, Ca2+, and Ba2+ by using chloroform as the nonpolar layer showed that two examples, the pyridineo crown ethers (3a) and (5b), transport barium and thallium picrates respectively with significant selectivity.
The Preparation of Macrocyclic Polyether-Diester Compounds by Transesterification Including The Preparation of Two New Nitrogen Containing Diester-Crown Compounds
Bradshaw, Jerald S.,Jones, Brian A.,Nielsen, Ralph B.,Spencer, Neil O.,Thompson, Patricia K.
, p. 957 - 962 (2007/10/02)
Macrocyclic polyether-diester compounds have been prepared by reacting oligoethylene glycols with the appropriate dimethyl esters in the presence of catalytic amounts of alkali metal methoxides.The methanol by-product was removed by molecular sieves.Product yields were improved for the preparation of all macrocyclic compounds except a compound containing a furan subcyclic group (4).Six new macrocyclic diester compounds (7-12) could only be prepared using the base catalyzed transesterification process since the acid chloride synthetic method failed or the acid chloride could not be made.The formation of compounds 5 and 6 from dimethyl 2,6-pyridine dicarboxylate (17) and the triethylene and tetraethylene glycols proceeded by way of half-transesterified intermediates.These intermediates were also observed for the base catalyzed decomposition of 5 and 6 in methanol to form the glycol and the diester 17.
