Regioselective routes to disubstituted dibenzo crown ethers and their complexations

Two isomers of bis(carbomethoxybenzo)-24-crown-8(cis-BCMB24C8, 1, and trans- BCMB24C8, 2) were synthesized regiospecically with acceptable to excellent yields. Cyclization in the presence of a template reagent, KPF6, led to an essentially quantitative yield of the potassium complex of the crown ethe...

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Published inOrganic & biomolecular chemistry Vol. 3; no. 11; pp. 2114 - 2121
Main Authors Gibson, HW, Wang, H, Bonrad, K, Jones, JW, Slebodnick, C, Zackharov, LN, Rheingold, AL, Habenicht, B, Lobue, P, Ratliff, AE
Format Journal Article
LanguageEnglish
Published CAMBRIDGE Royal Soc Chemistry 07.06.2005
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
POLYMERS
CONSTANTS
DIBENZO-24-CROWN-8
COMPLEXES
ALKALI-METAL IONS
ROTAXANES
EXCHANGE
ASSOCIATION
DISULFIDE
CATIONS
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Summary:Two isomers of bis(carbomethoxybenzo)-24-crown-8(cis-BCMB24C8, 1, and trans- BCMB24C8, 2) were synthesized regiospecically with acceptable to excellent yields. Cyclization in the presence of a template reagent, KPF6, led to an essentially quantitative yield of the potassium complex of the crown ether 1; the isolated cyclization yield of pure 1 was a remarkable 89 %! The methods not only avoid the very difficult separation of the isomers, but also greatly shorten the synthesis time by eliminating syringe pump usage during cyclization. The complexations of the isomeric BCMB24C8 with dibenzylammonium hexafluorophosphate ( 10) were studied by NMR; association constants (K-a) for 1 and 2 with the dibenzylammonium cation are 190 and 312 M-1, respectively. The X-ray crystal structures of crown ether 2 and the complexes 1(.)KPF(6), 2(.)KPF(6) and pseudorotaxane 2(.)10 were determined.
ISSN:1477-0520
1477-0539
DOI:10.1039/b503072m