Benzo-15-crown-5 ether

Accordingly, iV-phenyl-substituted isothiazolium salts bearing a benzo crown ether substituent were employed in this synthetic protocol and led to the synthesis of various crown ether-substituted 6aA4-thia-l,6-diazapentalenes 201... 

Barboiu, M Hovnanian, N., Luca, C. and Cot, L. (1999) Functionalized derivatives of benzo-crown-ethers, V, Multiple molecular recognition of zwitterionic phenylalanine. Tetrahedron, 55, 9221—9232. 

A deeper insight into the operation of the oxygen-atom effect as well as a further assessment of its dependence on chain length is provided by an investigation of Illuminati et al., (1981) on the kinetics of formation of benzo-crown ethers (54a) and of the analogous non-cyclisation reaction (54b)... 

Fig. 13 Log EAZ-values for the formation of (O) catechol polymethylene ethers [2] and ( ) benzo-crown ethers [20] in 99% Me2SO at 25°C plotted against the number of single bonds, r, in the chain connecting the end-groups. (Data from Illuminati et al., 1981)...

The effects observed for the shorter chains are easily understood as a strain relief phenomenon. Indeed, as Illuminati et al. (1981) have noted, replacement of suitably placed methylenes of diethers [2] with oxygens to give the corresponding benzo-crown ethers [20] transforms two 1,4-CH- -0 and (x—1) 1,4-CH -HC into 1,4-0 -O interactions, and 2(x—1)... 

The close adherence of the calculated curve to the actual behaviour of polyoxyethylene chains is further substantiated by comparison with the kinetic EM s for the formation of the 30- and 48-membered benzo-crown ethers [20] in 99% Me2SO (Illuminati et al., 1981 see Fig. 13). Assuming that for... 

The effect of substituents on the ion-binding capacity of benzo-crown ethers [76] has been studied in acetone solution (Ungaro et al., 1976). For the... 

Log AT, values for substituted benzo-crown ethers [76] in acetone at 25°Ca... 

A series of polyether macrocycles [59]—[66] (Fig. 33) that contain a coordinated reducible, redox-active 16-electron molybdenum nitrosyl (Mo(NO)(3+ group have been prepared (Al-Obaidi et al, 1986 Beer et al., 1987). Compounds [59]—[63] were synthesized from the reactions between [Mo(NO)LX2] (L = tris(3,5-dimethylpyrazolyl)hydroborate X = Cl or I ) and the appropriate amine substituted benzo-crown ether. Compounds... 

Fig. 34 The redox-active bipyridinium bis(benzo)-crown ether [67],...

Benzo crown ether, 39 115-116 Benzoin, catalytic oxidation scheme, 33 62 Benzonitrile, reaction with hexafluoroacetone, 30 268... 

A Monte-Carlo study is conducted of the formation of benzo-crown ethers from an acyclic precursor. The major features of the computed cyclization constants are in harmony with trends observed in kinetic constants reported. 

From the o-dichlorobenzene complex, reaction with a dialkoxide can produce a cyclic bisether. This idea has been applied in the preparation of benzo-crown ethers, as outlined in Scheme 6.61 The first substitution product (15) does not undergo cyclization, but a second intermolecular substitution to give (16) sets up a final cyclization to the bischromium complex (17) the overall yield is 27%. A bisthia analog was also prepared.61... 

Fig. 11. Crystal structure of [(18)Na]PF6 showing (a) the Na bound to all five oxygens of the benzo crown ether (b) the Na lying above the 15-crown-5 ligand coordinated to...

Beer PD et al (1990) Redox-responsive crown ethers containing a conjugated link between the ferrocene moiety and a benzo crown ether. Inorg Chem 29 378-381... 

The macrocyclic revolution in metal ion coordination chemistry [115] soon had repercussions on the design of fluorescent sensors for alkali cations. Before the advent of PET sensors, the first examinations of crown ether receptors with adjacent n-eleetron systems such as naphtho- and benzo crown ethers (50) [116] and (51) [117, 118] showed small but significant alkali cation induced fluore-... 

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