Benzo-24-crown-8 derivatives

The incoiporation of two asymmetric precursors into chiral crown ethers with C2 symmetiy must be carried out with total constitutional and stereochemical control during the reaction sequence. This has been accomplished elegantly during the synthesis of the three chiral benzo-15-crown-5 derivatives (SS)-79, and (5S)- 0 from (S)-lactic acid (122, 123). 

A number of benzo-15-crown-5 derivatives are known where chirality is associated with side chains or fused ring systems. For example, base-promoted reactions of l,ll-dichloro-3,6,9,-trioxaundecane with apomorphine and adrenaline have afforded the benzo-lS-crown-S derivatives 164 and 165, respectively... 

Employing similar reaction procedures and conditions, the corresponding benzo-15-crown-5 derivatives l-166 and 167 have been derived from L-Dopa... 

Studies by Photoswitchable Azobis(benzo-15-crown-5) Derivatives as a Molecular Probe... 

A variety of benzo-15-crown-5 derivatives with a carbohydrate... 

Tohda, K. Yoshiyagawa, S. Kataoka. M. Odashima. K. Umezawa, Y. Photoswitchable azobis(benzo-15-crown-5) derivatives as a molecular probe for phase boundary potentials at ion-selective poly (vinyl chloride) liquid membranes. Anal. Chem. 1997. 69, 3360-3369. 

In table 2 is shown the inhibitory activity of some crown ethersa-gainst three fungi. Some of them obviously suppressed the growth of the fungal mycelium. In the series of benzo-15-crown-5 derivatives ( 5, 7)... 

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. 

The introduction at the C- or N-terminal position of a crown ether unit has been used as a strategy to control the aggregation of poly(benzyl glutamate) derivatives 19 The incorporation of the crown unit at the C-terminal position is performed using (benzo-15-crown-5)-4-amine as initiator of the polymerization of l-G1u(OBz1)-NCA. Physical properties of such crown derivatives can be modulated by the formation of sandwich 2 1 complexes driven by the addition of specific alkali metal ions. In the reported case, the formation of K+ sandwich complex between two C-terminal benzo-15-crown-5 modified helical polypeptides induced aggregation. In a similar approach,f20 addition of Cs+ to 18-crown-6 terminated helical peptides results in the formation of supramolecular assemblies having membrane ion conductivity activities. 

Consider, for example, molecule 1 (Fig. 2), designed in the laboratories of de Silva [9] in Belfast. The fluorescence of anthracene derivatives has been shown, independently, to be quenched by tertiary amines, and also by benzo-crown ethers. The rationale behind the design of molecule 1 was such that, in its natural state, fluorescence of the anthracene unit would be quenched by electron transfer from the adjacent tertiary amine, and also from the sodium-... 

From the o-dichlorobenzene complex, reaction with a dialkoxide can produce a cyclic bis-ether. This idea has been applied in the preparation of benzo-crown ethers [33], their bisthia analog [33], and several dioxin derivatives [34]. 

In Group 14 few organometallic crown ether complexes have been investigated. An internally coordinated trimethyltin derivative of l,3-xylyl-17-benzo-crown-5 has... 

The benzo-crown ether 22 and its ntq>htho-analogue were synthesized from the corresponding 6-bromo-6-deoxy-derivatives by azide ion displacement. They are able to sequester dopamine presumably with the assistance of hydrogen bonding between the 6-amino-group and the phenolic hydroxyl functions on dopamine. ... 

The benzo crown compounds can be reduced to make the cyclohexo derivatives. Dicyclohexo-18-crown-6 (2) prepared by this method was found to be a mixture of two of the five possible isomers—the cis-syn-cis and the cis-anti-cis forms (8). Differential complexation separates the isomers (9). 

We have previously described the synthesis of calixcrowns by one-pot reactions. In a different approach the calix(aza)crowns were constructed by stepwise synthesis. The synthesis began with the condensation of cone-1,3-dialdehyde derivative 16 with various primary diamines to afford Schiff base-p-terr-butylcalix[4]arenes 17-20 in the cone conformation [29, 30]. Hydrogenation of 18 and 19 with NaBHt produced chlorohydrates 21HC1 and 22-HCl and subsequent deprotonation with NaOH lead to the di-aza-benzo-crown-ether-/j-tert-butylcalix[4]arenes 21 and 22 in almost quantitative yield [31] (Figure 6). 

The thermal properties of the benzo-crown enediynes esters and their complexes were studied by DSC [397]. In the absence of a hydrogen donor, the radicals polymerized evolving heat, which gave an exothermic peak in the DSC curve. The onset temperature of the exothermic peak corresponds to the temperature required for Bergman cyclization confirming the generation of free radicals. For the crown ether derivative 3.495 and its complexes 3.496 and 3.876, this temperature was... 

Diederich F, Jonas U, Gramlich V, Herrmann A, Ringsdorf H and Thilgen C 1993 Synthesis of a fullerene derivative of benzo[18]crown-6 by Diels-Alder reaction complexation ability, amphiphilic properties, and x-ray crystal structure of a dimethoxy-1,9-(methano[1, 2]benzomethano)fullerene[60] benzene clathrate Helv. Chim. Acta 76 2445-53... 

Many other cyclic and noncyclic organic carriers with remarkable ion selectivities have been used successfiilly as active hosts of various liquid membrane electrodes. These include the 14-crown-4-ether for lithium (30) 16-crown-5 derivatives for sodium bis-benzo-18-crown-6 ether for cesium the ionophore ETH 1001 [(R,R)-AA -bisd l-ethoxycarbonyl)undecyl-A,yVl-4,5-tctramcthyl-3,6-dioxaoctancdiamide] for calcium the natural macrocyclics nonactin and monensin for ammonia and sodium (31), respectively the ionophore ETH 1117 for magnesium calixarene derivatives for sodium (32) and macrocyclic thioethers for mercury and silver (33). 

If the photoequilibrium concentrations of the cis and trans isomers of the photoswitchable ionophore in the membrane bulk and their complexation stability constants for primary cations are known, the photoinduced change in the concentration of the complex cation in the membrane bulk can be estimated. If the same amount of change is assumed to occur for the concentration of the complex cation at the very surface of the membrane, the photoinduced change in the phase boundary potential may be correlated quantitatively to the amount of the primary cation permeated to or released from the membrane side of the interface under otherwise identical conditions. In such a manner, this type of photoswitchable ionophore may serve as a molecular probe to quantitatively correlate between the photoinduced changes in the phase boundary potential and the number of the primary cations permselectively extracted into the membrane side of the interface. Highly lipophilic derivatives of azobis(benzo-15-crown-5), 1 and 2, as well as reference compound 3 were used for this purpose (see Fig. 9 for the structures) [43]. Compared to azobenzene-modified crown ethers reported earlier [39 2], more distinct structural difference between the cis... 

When a membrane based on a derivative of azobis(benzo-15-crown-5) in contact with a solution of a primary cation is exposed to visible light, we assume that the iono-phore within the membrane phase is exclusively in the trans isomer and forms a 1 1 ionophore (I)-cation (M+) complex with a stability constant, trans. According to Eq. (10), the corresponding charge density at the membrane side of the interface, o is > can be expressed as... 

Polytopic macrocyclic receptors 1, 2 (Figure 10.1) are able to complex the zwitterionic form of the amino acids by a double non-covalent charge interaction [28,29]. The unsymmetrical benzocrown sulfonamide derivative, 2 which contains benzo-18-crown-6 and benzo-15-crown-5 moieties was used as a ditopic receptor for multiple molecular recognition of the amino acids, by combining two non-covalent interactions ammonium-crown hydrogen bonding and carboxylate- complexed Na+-benzo-15-crown-5 charge interactions [28,33]. 

Barboiu, M., Supuran, C.T., Luca, C., Popescu, G. and Barboiu, C. (1996) Functionalized derivatives of benzocrown-ethers. Part I. Ionophores containing amino and pyridinium groups derived from benzo-15-crown-5, benzo-18-crown-6 and dibenzo-18-crown-6. Liebigs Annalen der Chemie, 959-963. 

The reaction mode depends mainly on the choice of the base and reaction conditions, but route B is usually more common. Thus, tetrahydro-l,4-thiazine derivative 157 the structure of which was proved by X-ray crystal structure analysis (Fig. 7) [22b] was obtained in the reaction of the chloro ester 1-Me with 2-aminoethanethiol (156) using K2CO3 or EtgN as a base in 43 and 20% yield, respectively (Scheme 49) [22b, 26]. In the latter case, the secondary amino group in the primary tetrahydrothiazine product 157 underwent Michael addition to a second molecule of 1-Me to give 2-[r-(spirocyclopropanetetrahydrothiazinyl) cyclopropyl]-2-chloroacetate 158 (14% yield). When KOH in the presence of di-benzo-18-crown-6 was employed, however, the seven-membered heterocycles 155 (42%) and 159 (48%) were obtained upon reaction of 1-Me with 1,3-pro-panedithiol and 2-aminoethanethiol, respectively (Scheme 49) [26]. 

A chiral benzo-14-crown-4 derivative (RR)-T1 has been prepared (121) from (2J ,3J )-2,3-butanediol by applying to the chiral diol a chain extension procedure that involves (i) addition of aciylonitrile to both hydroxyl groups, (ii)... 

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