Ethers, azacrown

Azacrown ethers as enzyme mimics of ATPase 99MI17. 

Supramolecules and supramolecular assemblies including silsesquioxanes and azacrown ethers fragments as liquid crystals with restricted molecular topology 98CC2057. 

The preparation of novel triazole-containing 20-22 membered macrocyclic azacrown ether-thioethers was reported <96JCR(S)182> and the first selective synthetic method fra the synthesis of dicyanotriazolehemiporhyrazines was published <96JOC6446>. 1,2,4-Triazole-containing polyimide beads were prepared and employed as Mo(VI) epoxidation catalyst supports, liie 1,2,4-nitronyl nitroxide 29 was also synthesized and found to have remarkable magnetic properties <96AM60>. 

Ring-opening with heteroatomic nucleophiles is certainly among the most thoroughly studied behavior of epoxides, and this reaction continues to be a versatile workhorse of synthetic utility. This is exemplified in the recent literature by the examples of the p-cyclodextrin-catalyzed aminolysis of simple epoxides by aniline derivatives (i.e., 53 - 54) <00SL339> and the synthesis of oxa-azacrown ethers through the treatment of Ws-epoxides 55 with diamines 56. Yields in the latter synthesis are sensitive to the size of the macrocycle and substitution on the bis-epoxide <00TL1019>. 

The asymmetric Darzens condensation, which involves both carbon-carbon and carbon-oxygen bond constructions, was realized by use of the chiral azacrown ether 75als2,s ,ss and the quaternary ammonium salts derived from cinchona alka-loids159"621 under phase transfer catalyzed conditions. The a,p-epoxy ketone 80 (R=Ph) was obtained with reasonable enantioselectivity by the reaction of... 

Asymmetric a-hydroxylation of ketones 97 through phase transfer catalysis under alkaline conditions was realized by use of the Merck catalyst 7 (R=4-CF3, X=Br)[721 as well as the chiral azacrown ether 98[731 in conjunction with molecular oxygen, as shown in Scheme 30. The highest enantioselectivity of 79% ee was attained in the a-hydroxylation of the tetralone 100 by use of the Merck cata-... 

P. Bako, T. Kiss, L. Toke, Chiral Azacrown Ethers derived from D-Glucose as Catalysts for Enantioselective Michael Addition , Tetrahedron Lett. 1997, 38, 7259-7262. 

P. Bako, K. Vizvardi, S. Toppet, E. V. der Eycken, G. J. Hoonaert, L. Toke, Synthesis, Extraction Ability and Application in Asymmetric Synthesis of Azacrown Ethers derived from D-Glucose , Tetrahedron 1998, 54, 14975-14988. 

P. Bako, T. Novak, K. Ludanyi, B. Pete, L. Toke, G. Kegle-vich, D-Glucose-based Azacrown Ethers with a Phos-phonoalkyl Side Chain Application as Enantioselective Phase Transfer Catalysis , Tetrahedron Asymmetry 1999,10, 2373-2380. 

Axle and collar molecular structure, 27 60-61 Axokine, 3 97 Azaboranes, 4 170, 204 Azacarbocyanine dyes, 9 257 Aza[18]crown-6, 24 41 Aza[18]crown-6 appended a-helical barrels / rods, 24 58 Azacrown ethers, 24 44 Azacrowns, 24 41 Azacryptands, 24 42 Azadirachtin, 24 474 Azafullerenes, 22 231, 232, 243 Azahomofullerenes, 22 243 Azaindene compounds, 29 197 Azalactone method (for Emphaze supports), for covalent ligand immobilization, 6 396t Azamethiphos (salmosan)... 

The compounds [9] and [10] were synthesized in an effort to increase the through-space interaction between the ferrocene moiety and the bound cation (Scheme 3). These ligands were prepared by reaction of two equivalents of the corresponding mono-azacrown ether with bis(chlorocarbonyl)ferrocene. 

The catalysed A/-alkylation of the potassium salt of sulphoximines in l, 2-dimethoxyethane produces yields in excess of 90% [48]. Similarly, azacrown ethers have been synthesized by alkylation of bis(tosyIamino)alkyl ethers under catalysed basic two-phase conditions [49] (Scheme 5.12). The yields of the cyclic products (Table 5.24) are influenced by the choice of the alkali metal hydroxide employed, suggesting that there is a degree of template control in the ring closure step. This is not the case in the analogous reaction of p-toluenesulphonamide with a, co-dihaloalkanes [50], which leads to the formation of a mixture of l l and 2 2 cyclic products... 

The bis-sulphonamide (0.02 mol) and the a,o-dibromo compound (0.02 mol) in PhH (or PhMe) (600 ml) are added to a refluxing two-phase system of aqueous NaOH (7.5%, 100 ml) and PhH (or PhMe) (100 ml) containing TBA-I (1.85 g, 5 mmol). The mixture is stirred under reflux for 8-10 h and then cooled to room temperature. The organic phase is separated, dried (MgS04), and evaporated to yield the A-tosyl azacrown ether which, upon treatment with acid, is converted into the azacrown ether. 

Tsuchiya T, Sato K, Kurihara H, Wakahara T, Nakahodo T, Maeda Y, Akasaka T, Ohkubo K, Fukuzumi S, Kato T, Mizorogi N, Kobayashi K, Nagase S (2006) Host-guest complexation of endohedral metallofullerene with azacrown ether and its application. J. Am. Chem. Soc. 128 6699-6703. 

Electrochemical oxidation of cadmium in a solution of ](4-methylphenyl)sulfonyl]-2-pyridylamine] (HL) in acetonitrile/di chloromethane mixtures resulted in CdL2 complex formation [149]. The electrochemical oxidation of cadmium amalgam in nonaqueous solvents CH2CI2, 1,2-C2H4CI2, and PC was also used for the preparation of cadmium complexes with 18-membered macromonocyclic ligands, 18-06, 18-S6, I8-N2O4, and 18-N6 [150]. The stoichiometry and stability of resulted complexes were determined. The same method was used to examine the complexation of Cd(II) cation with 12-crown-4 ether, azacrown ether 1,4,8,11-tetra-azacyclotetradecane, and thiaazacrown... 

Macrocyclic 25 has been constructed with pseudocryptand 26 which can be discerned within Tsien s ratiometric fluorescent sensors as the Na receptor unit. Conformational changes by 26 upon ion binding allows strong off-on PET sensing action due to the ion-induced increase of its oxidation potential. X-ray structural evidence for the Na -induced conformational changes in 26 shows decreased conjugation with a 40° twist about the C-N bond of the 2-anisidine unit. X-ray evidence is also available for similar conformational changes in the non-macro-cyclic Ca " receptor 23. A related analysis has been made for a Ag" -phenyl-azacrown ether interaction which involves a soft-soft component. ... 

Hori, K., Tamura, M., Tani, K., Nishiwaki, N., Ariga, M. and Tohda, Y. Asymmetric Epoxidation Catalyzed by Novel Azacrown Ether-type Chiral Quaternary Ammonium Salts under Phase-transfer Catalytic Conditions. Tetrahedron Lett. 2006, 47, 3115-3118. 

Asymmetric epoxidation catalyzed by novel azacrown ether-type chiral... 

Synthesis of the azacrown ether-t)fpe quaternary ammonium salt. 232... 

ASYMMETRIC EPOXIDATION CATALYZED BY NOVEL AZACROWN ETHER-TYPE CHIRAL QUATERNARY AMMONIUM SALTS UNDER PHASE-TRANSFER CATALYTIC CONDITIONS... 

SYNTHESIS OF THE AZACROWN ETHER-TYPE QUATERNARY AMMONIUM SALT... 

To the precipitate was added dichloromethane, and then the combined organic extracts were filtered and concentrated in vacuo to afford the corresponding azacrown ether-type quaternary ammonium salt (0.27 g, 85%) as a light brown crystalline solid. The purity of the cmde product is high enough to be used in the catalysis experiments, m.p. 118-119 °C [a]p 71 (c= 1.0, CHCI3). 

ASYMMETRIC EPOXIDATION OF (E)-CHALCONE CATALYZED BY THE AZACROWN ETHER-TYPE QUATERNARY AMMONIUM SALT AS CHIRAL PTC... 

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