Simons electrochemical fluorination of substituted homopiperazines(hexahydro-1,4-diazepines) and piperazines

Simons electrochemical fluorination (ECF) of 1,4-dimethyl-1,4-homopiperazine, methyl 4-ethylhomopiperazin-1-ylacetate and 1,4-bis(methoxycarbonylmethyl)-1,4-homopiperazine was studied. For comparison, ECF of three piperazines with a N-(methoxycarbonylmethyl) group(s) was also studied. ECF of 1,4-dimethyl-1,4-homopiperazine gave a low yield of corresponding perfluoro(1,4-dimethyl-1,4-homopiperazine) together with perfluoro(2,6-diaza-2,6-dimethylheptane) as the major product. Corresponding perfluoro(homopiperazines) with mono- and/or di-(fluorocarbonyldifluoromethyl) groups [CF₂C(O)F] at the 1- and/or 4-position were formed in low yields from methyl 4-ethylhomopiperazin-1-ylacetate and 1,4-bis(methoxycarbonylmethyl)-1,4-homopiperazine, respectively. These new seven-membered perfluoro(1,4-dialkyl-1,4-homopiperazines) were accompanied by the formation of mono- and/or di-basic linear perfluoroacid fluorides resulting from the CC bond scission at the 2- and 3-positions of the ring. From mono- and/or di-N-(methoxycarbonylmethyl)-substituted piperazines, corresponding perfluoropeperazines having the acid fluoride group(s) were formed in low yields.     

Estimating tissue permeability and other bioelectrical parameters using membrane voltage and short-circuit current

Evaluating the acute toxic effects of drugs or toxins is based mainly on studies which require the use of light microscopy. Recently, the effects of such substances on biological membranes, such as the nasal membrane, has been studied using the traditional Ussing chambers, which make it possible to study the transepithelial flux of drugs across membranes and to measure some bioelectrical parameters. A model is described, with which the changes in the membrane permeability, for sodium, potassium and chlorine, can be calculated directly, based on values obtained from the Ussing chamber system. Also, an experiment is described for evaluating the toxic effects of the cholera toxin B subunit, by measuring these changes in isolated rabbit nasal mucosa.     

Binary mixtures of cyclohexanone, 2-butanone, 1,4-dioxane and 1,2-dimethoxyethane

Densities and sound velocities of binary mixtures of cyclohexanone, 2-butanone, 1,4-dioxane and 1,2-dimethoxyethane were measured at 298.15 K and also the densities at 303.15 K. Excess volumes were determined from densities. Isentropic compressibilities were determined from densities and sound velocities, and excess thermal expansion factors were determined from excess volumes of two temperatures. Excess isothermal compressibilities and excess isochoric heat capacities were then estimated using excess isobaric heat capacities previously reported. Excess volumes and excess isentropic and isothermal compressibilities were negative except for cyclohexanone+1,4-dioxane system. This revised version was published online in August 2006 with corrections to the Cover Date.     

Anion binding to a ferric porphyrin complexed with per-O-methylated beta-cyclodextrin in aqueous solution

5,10,15,20-Tetrakis(4-sulfonatophenyl)porphinato iron(III) (Fe(III)TPPS) forms a very stable 1:2 complex with heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TMe-beta-CD), whose iron(III) center is located at a hydrophobic cleft formed by two face-to-face TMe-beta-CD molecules. Various inorganic anions (X(-)) such as F(-), Cl(-), Br(-), I(-), N(3)(-), and SCN(-) coordinate to Fe(III)TPPS(TMe-beta-CD)(2) to form five-coordinate high-spin Fe(III)TPPS(X)(TMe-beta-CD)(2), while no coordination occurs with ClO(4)(-), H(2)PO(4)(-), NO(3)(-), and HSO(4)(-). Except for F(-), none of the anions investigated coordinate to Fe(III)TPPS in the absence of TMe-beta-CD due to extensive hydration to the anions as well as to Fe(III)TPPS. The present system shows a high selectivity toward the N(3)(-) anion. The thermodynamics suggests that Lewis basicity, hydrophilicity, and shape of an X(-) anion are the main factors to determine the stability of the Fe(III)TPPS(X)(TMe-beta-CD)(2) complex.     

Study of ions with excess kinetic energy. III—Mass spectra of excess kinetic energy ions of aliphatic amines

The mass spectra obtained from ions having excess kinetic energy (named the excess kinetic energy mass spectra) formed by electron impact of several aliphatic amines have been studied. Comparison with the excess kinetic energy mass spectra of the analogous alcohols shows many similarities. For example, the intensity of the [CH₂OH]⁺ ion of an aminoalcohol is about the same as the intensity of the [CH₂NH₂]⁺ ion. The excess kinetic energy mass spectra give useful information about the presence or absence of various functional groups, such as CH₂NH₂, CH₂OH, CH₃CHNH₂ and alkyl groups, and also about rearrangements. The fragmentation mechanisms are straightforward and applicable to a variety of classes of compounds. The molecular weight dependence of excess kinetic energy mass spectra is described.     

Intermolecular methyl transfer on pyrolysis of carpronium chloride

The methyl transfer occurring in the production of methyl N,N-dimethyl-γ-aminobutyrate by pyrolysis of carpronium chloride was examined by means of pyrolysis gas chromatography mass spectrometry with the aid of some deuterated compounds. The mass spectra of methyl N,N-dimethyl-γ-aminobutyrate, produced from deuterated derivatives of carpronium chloride, showed inter alia, characteristic molecular ion peaks which indicated that the methyl of the trimethylammonium group transfers and displaces the methyl of the carbomethoxy group of the tertiary amino compound. The results show that an intermolecular methyl transfer occurs in part on pyrolysis of carpronium chloride, to form methyl N,N-dimethyl-γ-aminobutyrate in which the methyl oxygen is replaced by a methyl from the nitrogen of the original compound. The mechanism presented involves the bimolecular reaction between zwitterionic intermediates formed by ionic O-demethylation of carpronium chloride.     

Optically active antifungal azoles. VIII. Synthesis and antifungal activity of 1-[(1R,2R)-2-(2,4-difluoro- and 2-fluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol-1-yl)propyl]- 3-(4-substituted phenyl)-2(1H,3H)-imidazolones and 2-imidazolidinones

New optically active antifungal azoles, 1-[(1R,2R)-2-(2,4-difluoro- and 2-fluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol-1-yl)propyl ]-3-(4- substituted phenyl)-2(1H,3H)-imidazolones (1,2) and 2-imidazolidinones (3,4), were prepared in a stereocontrolled manner from (1S)-1-[(2R)-2-(2,4- difluoro- and 2-fluorophenyl)-2-oxiranyl]ethanols (15, 16). Compounds 1-4 showed potent antifungal activity against Candida albicans in vitro and in vivo, as well as a broad antifungal spectrum for various fungi in vitro. Furthermore, the imidazolidinones, 3b--e and 4d, e, were found to exert extremely strong growth-inhibitory activity against Aspergillus fumigatus.