RESUMEN

Azulen-2-ylboronic acid pinacol ester, prepared by iridium-catalyzed C-H borylation of azulene, efficiently underwent iododeboronation with a stoichiometric amount of copper(I) iodide. This reaction allowed the synthesis of 2-iodoazulene in only two steps starting from azulene. This methodology was successfully applied to analogous azulenes.

RESUMEN

Photoinduced catalytic Michael-type radical addition was achieved via olefin insertion into a nonacidic C(sp3)-H bond, utilizing 2-chloroanthraquinone as a C-H bond-cleaving catalyst and 1,1-bis(phenylsulfonyl)ethylene as an olefinic substrate. The present radical protocol allows carbon chain extension stemming from nonacidic C-H bonds, which complements alkylation at acidic C-H bonds under ionic conditions and installs the active methine site that acts as a versatile synthetic handle for further transformations.

RESUMEN

In a mixed-valence polyoxometalate, electrons are usually delocalized within the cluster anion because of low level of inter-cluster interaction. Herein, we report the structure and electrical properties of a single crystal in which mixed-valence polyoxometalates were electrically wired by cationic π-molecules of tetrathiafulvalene substituted with pyridinium. Electron-transport characteristics are suggested to represent electron hopping through strong interactions between cluster and cationic π-molecules.

RESUMEN

A series of hypervalent organobismuth(III) compounds derived from alkyl aryl ketones [XBi(5-R'C6H3-2-COR)(Ar)] was synthesized to investigate the effect of the compounds' structural features on their antifungal activity against the yeast Saccharomyces cerevisiae. In contrast to bismuth heterocycles [XBi(5-RC6H3-2-SO2C6H4-1'-)] derived from diphenyl sulfones, a systematic quantitative structure-activity relationship study was possible. The activity depended on the Ar group and increased for heavier X atoms, whereas lengthening the alkyl chain (R) or introducing a substituent (R') reduced the activity. IBi(C6H4-2-COCH3)(4-FC6H4) was the most active. Its activity was superior to that of the related acyclic analogues ClBi[C6H4-2-CH2N(CH3)2](Ar) and ClBi(C6H4-2-SO2 tert-Bu)(Ar) and also comparable to that of heterocyclic ClBi(C6H4-2-SO2C6H4-1'-), which was the most active compound in our previous studies. Density function theory calculations suggested that hypervalent bismuthanes undergo nucleophilic addition with a biomolecule at the bismuth atom to give an intermediate ate complex. For higher antifungal activity, adjusting the lipophilicity-hydrophilicity balance, modeling the three-dimensional molecular structure around the bismuth atom, and stabilizing the ate complex appear to be more important than tuning the Lewis acidity at the bismuth atom.

Asunto(s)

Antifúngicos/química , Antifúngicos/farmacología , Bismuto/química , Compuestos Organometálicos/química , Compuestos Organometálicos/farmacología , Saccharomyces cerevisiae/efectos de los fármacos , Antifúngicos/síntesis química , Cetonas/química , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Compuestos Organometálicos/síntesis química , Relación Estructura-Actividad Cuantitativa , Relación Estructura-Actividad , Sulfonas/química

RESUMEN

A series of heterocyclic organobismuth(III) carboxylates 4 and 5 [RCO2Bi(C6H4-2-SO2C6H4-1'-)] derived from diphenyl sulfone was synthesized to determine the influence of the carboxylate ligand structure on the lipophilicity and antifungal activity against the yeast Saccharomyces cerevisiae. In contrast to the clear structure-activity relationship between the size of the inhibition zone and the value of ClogP for specific substitution on diphenyl sulfone scaffold 1 [ClBi(5-RC6H3-2-SO2C6H4-1'-)], scaffolds 4 and 5 showed similar inhibition activities irrespective of the ClogP value. This suggests that these molecules function inside the yeast cell by separating into the cationic heterocyclic bismuth scaffold and the anionic carboxylate moiety, and that the bismuth scaffold plays an important role in the inhibition activity.

Asunto(s)

Bismuto/química , Ácidos Carboxílicos/síntesis química , Compuestos Heterocíclicos/síntesis química , Compuestos Organometálicos/síntesis química , Sulfonas/química , Antifúngicos/síntesis química , Antifúngicos/química , Antifúngicos/farmacología , Compuestos de Bifenilo/química , Ácidos Carboxílicos/química , Ácidos Carboxílicos/farmacología , Compuestos Heterocíclicos/química , Compuestos Heterocíclicos/farmacología , Lípidos/química , Pruebas de Sensibilidad Microbiana , Modelos Químicos , Estructura Molecular , Compuestos Organometálicos/química , Compuestos Organometálicos/farmacología , Saccharomyces cerevisiae/efectos de los fármacos , Relación Estructura-Actividad

RESUMEN

A new salt-[Ni(II)(DMSO)(5)(TTFPy)](2)[α-SiW(12)O(40)] (1)-based on polyoxometalates was prepared by coordinating a cationic electron donor of pyridyltetrathiafulvalene (TTFPy) with Ni(II). Although the TTFPy molecule did not form a salt with the anionic α-[SiW(VI)(12)O(40)](4-) because of the weak charge-transfer (CT) interaction, the coordination of Ni with the pyridyl moiety permitted salt formation driven by electrostatic interaction, giving a single crystal of 1. Crystallographic analysis, UV-vis and IR spectroscopy and electrochemical characterization revealed that the fully oxidized α-[SiW(VI)(12)O(40)](4-) was crystallized with the neutral TTFPy moiety from the acetonitrile solution because of the low electron-withdrawing ability of α-[SiW(VI)(12)O(40)](4-), forming a brown-orange crystal. The crystal colour quickly turned to black by immersing in methanol, due to CT from TTF moiety to α-[SiW(VI)(12)O(40)](4-), which was caused by the solvent effect. Increase in the solvent acceptor number from 18.9 for acetonitrile to 41.3 for methanol resulted in the enhancement of the electron withdrawing ability of α-[SiW(VI)(12)O(40)](4-) by 0.317 V in methanol.

RESUMEN

The dual Meissner effect is observed without monopoles in quenched SU(2) QCD with Landau gauge fixing. Magnetic displacement currents that are time-dependent Abelian magnetic fields act as solenoidal currents squeezing Abelian electric fields. Monopoles are not always necessary for the dual Meissner effect. A mean-field calculation suggests that the dual Meissner effect through the mass generation of the Abelian electric field is related to a gluon condensate A(a)(mu)A(a)(mu) not equal 0 of mass dimension 2.

RESUMEN

The photoexcitation of a self-assembled M6L4-type coordination cage accommodating photochemically inert alkane guests (e.g., adamantane and cyclooctane) led to the regioselective oxidation of the guest within the cage. Under anaerobic conditions, the guest oxidation was accompanied by the stable radical formation as indicated by ESR spectrometry (g = 2.002) and change in solution color (from colorless to blue). These phenomena were shown to be characteristic of the self-assembled molecular systems: i.e., from the M6L4 supersetGn assembly, none of the components (M, L, or G) can be eliminated for the unusual oxidation and/or radical formation.

RESUMEN

alpha,alpha,alpha-Trifluoroacetophenone oxide, generated by (1)O(2) oxidation of Ph(CF(3))CN(2), reacted electrophilically with sulfoxides (rho = -0.74 vs sigma; r = 0.95) affording sulfides as the major product. The intermediacy of persulfoxides formed via cyclic peroxidic sulfuranes in the novel deoxygenation was evidenced by an (18)O-tracer study and by the formation of benzaldehyde in the reaction with benzyl phenyl sulfoxide. Olefins were oxidized to epoxides during the photooxidation of Ph(CF(3))CN(2). From the fact that the epoxidation proceeded almost stereospecifically and the substituent effect on styrenes resulted in the negative rho-value of -1.66 vs sigma (r = 0.97), a dioxirane was proposed as the second intermediate which might be formed by the isomerization of carbonyl oxide. Trapping experiments with styrenes and sulfoxides suggested that the cyclization of carbonyl oxide is competitive with the reaction with sulfoxides. In contrast to the known nucleophilic nature of carbonyl oxides, the present oxide is shown to have an electrophilic character, indicating that the reactivity of carbonyl oxides could be controlled by substituents.