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Facile and efficient methods for the synthesis of 3‐benzylquinoxalin‐2(1H)‐ones and thiazolo[3,4‐a]quinoxalin‐4(5H)‐ones by the reaction of the readily available 3‐(α‐chlorobenzyl)quinoxalin‐2(1H)‐ones and thiourea have been developed, with multiple roles of the latter. Possible mechanisms are discussed. These two‐step sequences can be performed in a one‐pot manner to produce the desired products in moderate to high yields. [ABSTRACT FROM AUTHOR]

The present work highlights the key aspects of the influence of calix[4]arene and tetrathiacalix[4]arene scaffolds on the structural and photophysical properties of Tb3+ complexes with tetra-1,3-diketone derivatives of the macrocycles in DMF solutions. The equilibrium forms of Tb3+ complexes with unsubstituted and functionalized by acetylacetonyl groups at the upper rim of calix[4]arenes and thiacalix[4]arenes are revealed from UV-, NMR, MALDI TOF mass spectroscopy, quantum-chemical calculations at the DFT level and luminescence spectroscopy data. In alkaline DMF solutions, the ligands form predominantly 1 : 1 complexes with Tb3+ ions. However, the replacement of a calix[4]arene-scaffold by a thiacalix[4]arene-scaffold in the tetra-1,3-diketone derivatives shifts the equilibrium forms of Tb3+ complexes from monomeric to the dimeric ones. DFT calculations in combination with experimental data reveal the most reliable structures of complexes. The quantitative analysis of the photophysical parameters in correlation with the structural features of the complexes highlights the specific inner-sphere environment of Tb3+ ions in the dimeric complexes with the thiacalix[4]arene derivatives as a reason for greater sensitization of Tb3+-centered luminescence. [ABSTRACT FROM AUTHOR]

[Display omitted] Reactions between 4-(propargyloxy)benzaldehyde with anthracene-9-carbaldehyde oxime or pyrene-1-carbaldehyde oxime in the presence of chloramine T in ethanol lead to new isoxazole-containing derivatives of benzaldehyde. The subsequent acid-catalyzed condensation of these compounds with 2-methylresorcinol in chloroform/trifluoroacetic acid mixtures affords novel calix[4]resorcinols with anthaceneand pyrene-ended isoxazole-containing fragments as all– cis (rccc) and cis–trans–trans (rctt) diastereoisomers, their ratios being dependent on the CF 3 CO 2 H percentage in the medium. The crystal structures of pyrene-ended isoxazole-containing benzaldehyde and corresponding calix[4]resorcinol rctt isomer have been established by single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

[Display omitted] The use of excess of trifluoroacetic acid in chloroform (1 : 1, v/v) in a one-pot acid-catalyzed cyclocondensation of functionalized benzaldehydes with 2-methylresorcinol significantly improves the yield of calix[4]resorcinol rccc diastereoisomers compared to rctt ones. The fraction and yield of the rccc isomers sometimes approach 100% along with shortening the reaction time. The structure of new rccc diastereoisomer of chlorine-containing calix[4]resorcinol has been established by single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Nanoassociates containing folic acid (FA) were obtained through solubilization by colloid solutions of three betaine calixresorcinarenes (sulfobetaine tetrapentylcalixresorcinarene С 5 -SB, hydroxysulfobetaine tetrapentyl- С 5 -hSB and tetraundecylcalixresorcinarene C 11 -hSB). FA was solubilized in its anionic form and fraction of bound molecules of FA was of from 89 % to 99 % (FT-PGSE NMR method data). The driving forces of FA encapsulation in the nanoassociates has been considered with the help of 1Н NMR, 2D NOESY NMR, and FT-PGSE NMR data. The macrocycle-FA nanoassociates have average hydrodynamic diameters of 3–5 nm (PDI of 0.184 0.238) and a zeta potential close to zero; however, they were stable for 4–8 weeks. The enhancement of the internalization of the macrocycle-FA nanoassociates into M-HeLa cells compared to unloaded macrocycles self-associates was shown by the flow cytometry and fluorescence microscopy methods. Additionally, the growth of cytotoxicity of Rhodamine B by 19 % in the presence of С 5 -SB+FA nanoassociates compared to С 5 -SB self-associates in the in vitro PDT experiment on M-HeLa cells was found. Overall, the potential of a supramolecular approach to obtaining folate-functionalized nanocontainers has been demonstrated. [Display omitted] • Betaine amphiphilic calixresorcinarenes solubilize and bind FA in anionic form. • The efficiency of FA binding in macrocycles' nanoassociates ranges from 89 % to 99 %. • Macrocycle-FA-RhB nanoassociates are toxic to M-HeLa cells under light irradiation. • FA introduction into macrocycle-RhB nanoassociates increases their toxicity up to 19 %. [ABSTRACT FROM AUTHOR]

The reactions of (L)-menthyl chloroacetate ((1 R ,2 S ,5 R)-2-isopropyl-5-methylcyclohexyl chloroacetate) with aromatic aldehydes under Darzens condensation conditions produce mixtures of four isomers of (L)-menthyl-3-arylglycidates in approximately equal quantities, of which (L)-menthyl (2 S ,3 S)-3-arylglycidates spontaneously crystallize when kept at the room temperature for a week. (L)-Menthyl (2 S ,3 S)-3-arylglycidates, in contrast to the mixtures of (2 S ,3 R) and (2 R ,3 S) isomers of (L)-menthyl 3-arylglycidates, which in reactions with benzene-1,2-diamine at boiling AcOH give 3-hydroxy-4-aryl-4,5-dihydro-1 H -benzo[ b ][1,4]diazepin-2(3 H)-ones, provide enantioselective formation of (L)-menthyl (2 S ,3 S)-2-hydroxy-3-(2-methylbenzimidazol-1-yl)-3-arylpropanoates. [Display omitted] • (L)-Menthyl chloroacetates with aromatic aldehydes where used in the synthesis of 3-arylglycidates. • (L)-Menthyl (2 S ,3 S)-3-arylglycidates spontaneously crystallize when kept at the room temperature. • (L)-Menthyl (2 S ,3 S)-3-arylglycidates in reactions with 1,2-BDA provide 3-arylpropanoates. • (2 S ,3 R) and (2 R ,3 S) isomers of (L)-menthyl 3-arylglycidates with 1,2-BDA give 1 H -benzo[ b ][1,4]diazepin--2(3 H)-ones. [ABSTRACT FROM AUTHOR]

The electrophilic activation of various substrates via double or even triple protonation in superacidic media enables reactions with extremely weak nucleophiles. Despite the significant progress in this area, the utility of organophosphorus compounds as superelectrophiles still remains limited. Additionally, the most common superacids require a special care due to their high toxicity, exceptional corrosiveness and moisture sensitivity. Herein, we report the first successful application of the "Brønsted acid assisted Brønsted acid" concept for the superelectrophilic activation of 2-hydroxybenzo[e][1,2]oxaphosphinine 2-oxides (phosphacoumarins). The pivotal role is attributed to the tendency of the phosphoryl moiety to form hydrogen-bonded complexes, which enables the formation of dicationic species and increases the electrophilicity of the phosphacoumarin. This unmasks the reactivity of phosphacoumarins towards non-activated aromatics, while requiring only relatively non-benign trifluoroacetic acid as the reaction medium. [ABSTRACT FROM AUTHOR]

A new copper (II) 1D coordination polymer (CP) of composition [9Cu·6L·4DMSO·3H 2 O] n has been prepared with use of N 1-(2-carboxyphenyl)- N 2-(4-ethylcarboxyphenyl)oxalamide as H 3 L ligand. The synthesis of the CP is based on a binuclear complex [Cu(H 2 L) 2 ·H 2 O] 2. A number of the [Cu(H 2 L) 2 ·H 2 O] 2 complexes were obtained as a result of exchange reaction between N 1-(2-carboxyphenyl)- N 2-(aryl)oxalamide triethylammonium salts (HEt 3 N+·(H 2 L)-) and CuCl 2 ·2H 2 O in an aqueous medium. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Amphiphilic zwitter-ionic calix[4]resorcinarenes form self-associates in an aqueous solution. • Calixresorcinarenes bearing undecyl and dodecyloxyphenyl chains are non-surface active. • Sulfobetaine and hydroxysulfobetaine calixresorcinarenes bearing pentyl chains are surface active. Here the amphiphilic calix[4]resorcinarenes, which form self-associates in an aqueous solution but do not exhibit surface activity, are described. Aqueous solutions of calix[4]resorcinarenes with different zwitter-ionic groups on the upper rim: carboxybetaine (C 5 -CB, C 11 -CB, C 12 OPh-CB), sulfobetaine (C 5 -SB, C 11 -SB), hydroxysulfobetaine (C 5 -hSB, C 11 -hSB), - and different hydrophobic substituents on the lower rim (pentyl, undecyl, dodecyloxyphenyl) were studied by fluorimetry, Fourier transform pulsed-gradient spin-echo (FT-PGSE) NMR spectroscopy, UV–vis spectroscopy, dynamic light scattering (DLS), and tensiometry. It was found that all macrocycles spontaneously form self-associates in an aqueous solution, but only sulfobetaine and hydroxysulfobetaine calixresorcinarenes with pentyl substituents on the lower rim are surface active. The critical association concentration (CAC) values, which were obtained by different methods, as well as values of averaged hydrodynamic diameter, averaged self-association numbers, solubilizing power, and other parameters of self-association are presented and discussed. [ABSTRACT FROM AUTHOR]

Abstract A new and highly efficient method for the synthesis of 4-(benzimidazol-2-yl)quinolin-2(1 H)-ones via the rearrangement of spiroquinoxalinones in moderate-to-excellent yields has been developed. The rearrangement represents a facile approach to medicinally important biheterocyclic compounds. Compared to other methods, the present protocol has a number of advantages such as – cost-effectiveness, avoidance of difficult of access quinolin-2-one and benzimidazole derivatives as reaction partners, and easy accessibility of starting materials, making it a highly practical approach to access various 4-(benzimidazol-2-yl)quinolin-2(1 H)-ones. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

An efficient sodium dithionite (Na 2 S 2 O 4 )-mediated method for construction of 3-hydroxyquinolines via in situ Meinwald rearrangement/intramolecular reductive cyclization of o -nitrobenzalacetophenone oxides has been developed. The practical approach is of excellent functional group compatibility with as high as 98% yield under mild reaction conditions. Moreover, further manipulation successfully furnished 4-bromo substituted derivatives which may provide a promising potential application in exploring biologically active analogs of 3-hydroxyquinolines. [ABSTRACT FROM AUTHOR]

A new type of calix[4]arene-bis-1,3-diketone derivatives, in which the chelate groups are directly conjugated through the carbonyl carbon atom to the aromatic moieties of calix[4]arene, demonstrates the dramatic effect of lower rim substituents on the coordination of Eu3+ ions with conjugated 1, 3-diketo groups. Eu3+ -luminescence is more enhanced in complexes with dipropoxy-calix[4]arene compared to complexes with the tetrapropoxy analogue due to the difference in the structure of the complex. [Display omitted] This work presents new type of bis-1,3-diketone calix[4]arene derivatives, in which the chelate groups are directly conjugated through the carbonyl carbon atom with aromatic fragments of calix[4]arene, and their lower rims bear four propoxy groups or pairs of hydroxy and propoxy groups. Tetrapropoxy-calix[4]arene is synthesized by acylation of magnesium enolates of a calix[4]arene ketone with 1-benzoylbenzotriazoles, and the dipropoxy analogue is obtained by bromination of bis(chalcone)-calix[4]arene, followed by methanolysis and hydrolysis. Significant conjugation of 1,3-diketo groups with the π-system of calix[4]arene is revealed for calixarenes of both types. Analysis of complexes formed by the ligands using the UV–Vis and NMR diffusion methods in combination with DFT calculations makes it possible to identify differences in the modes of complex formation of di- and tetrapropoxy- substituted ligands. It is demonstrated that a more enhanced sensibilization of Eu3+-luminescence in complexes with dipropoxy-calix[4]arene compared to that for complexes with tetrapropoxy-counterpart correlates with the formation of a tetrameric structure, in which the binding of Eu3+ ions does not disturb the conjugation of 1,3-diketonate moieties with aromatic calix[4]arene fragments. This is quite different from the significant disturbance of conjugation during intramolecular bis-chelation of Eu3+ ion by 1,3-diketo groups of tetraalkyl substituted ligand. [ABSTRACT FROM AUTHOR]