Reactions of 3-(Polyfluoroalkyl)propane-1,2,3-trione-2-oximes with Diaminoarenes

Novel quinoxaline derivatives have been synthesized via the reaction of 3-trifhioromethyl-1,2,3-propanetrione-2-oximes with 1,2-diaminobenzene or 2,3-diaminonaphthalene: 2-trifluoromethyl-3-aroylquinoxaline and 2-trifluoromethyl-3-aroylbenzo[g]quinoxaline. Under similar conditions, 3-R^F-1,2,3-propanetrione-2-oximes [R^F = C₃F₇, H(CF₂)₄, C₄F₉, and C₆F₁₃] with the same diaminoarenes have given a mixture of the condensation and fragmentation products in different ratios. The structure of (4-methylphenyl)[3-(tri-fluoromethyl)benzo[g]quinoxalin-2-yl]methanone has been elucidated by means of X-ray diffraction analysis.

     

Synthesis of 1,3,4-thiadiazoles containing the trifluoromethyl group

The following compounds have been synthesized: 2-Amino-5-trifluoromethyl-1,3,4-thiadiazole; N-(5-trifluoromethyl - 1,3,4-thiadizol-2-yl)benzenesulfonamide; N¹-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)sulfanilamide, its N⁴-acetyl, N⁴-succinyl, and N⁴-pathalyl derivatives; o - m - and p-trifluoromethylbenzoylthiosemicarbazide, their corresponding 2-amino-1,3,4-thiadiazoles, their corresponding sulfanilamides, their N⁴-acetyl, N⁴-succinyl and N⁴-phthalyl derivatives; 3-o-trifluoromethylphenyl-4H-1,2,4-triazole-5-thiol. Preliminary in-vitro assays show that synthesized sulfanilamide derivatives have antibacterial activity against Staphylococcus aureus.     

新型希土4-羟基-7-三氟甲基-3-喹啉基甲酸乙酯配合物的光物理性质

首次合成了五种新型希土(Eu³⁺, Tb³⁺, Gd³⁺, Sm³⁺, Dy³⁺)配合物。配体为带有喹啉环的4-羟基-7-三氟甲基-3-喹啉基甲酸乙酯。并用元素分析、红外光谱和热分析方法确定了配合物的组成。通过测定钆配合物的低温磷光光谱表明4-羟基-7-三氟甲基-3-喹啉基甲酸乙酯的三重态能级为22000 cm^-1。配合物的光物理性质表明配体的三重态能级适于希土Eu³⁺, Sm³⁺, Dy³⁺和Tb³⁺，特别是Tb³⁺的发光。     

Reactions of regioisomeric 3,3-dimethyl- and 2,2-dimethyl-6-trifluoromethyl-2,3-dihydro-4-pyrones with N-nucleophiles

Reactions of 2,2-dimethyl-6-trifluoromethyl-2,3-dihydro-4-pyrone with ethylenediamine, hydrazine, or hydroxylamine yield 5-methyl-7-trifluoromethyl-2,3-dihydro-1H-1,4-diazepine, 3(5)-(2-hydroxy-2-methylpropyl)-5(3)-trifluoromethylpyrazole, and 5-hydroxy-3-(2-hydroxy-2-methylpropyl)-5-triflouromethyl-Δ², respectively. The same compounds were obtained from 2-amino-1,1,1-trifluoro-6-hydroxy-6-methylhept-2(Z)-en-4-one and 2-hydroxy-6, 6-dimethyl-2-trifluoromethyltetrahydro-4-pyrone.     

Proton NMR probing of stoichiometry and thermodynamic data for the complexation of Na and Li ions with 15-Crown-5 in acetonitrile-nitrobenzene mixtures

Proton NMR was used to study the complexation reaction of Li⁺ and Na⁺ ions with 15-Crown-5 (15C5) in a number of binary acetonitrile (AN)-nitrobenzene (NB) mixtures at different temperatures. In all cases, the exchange between free and complexed 15C5 was fast on the NMR timescale and only a single population average ¹H signal was observed. The formation constants of the resulting 1:1 complexes in different solvent mixtures were determined by computer fitting of the chemical shift mole ratio data. There is an inverse relationship between the complex stability and the amount of AN in the solvent mixtures. The enthalpy and entropy values for the complexation reaction were evaluated from the temperature dependence of the formation constants. In all the solvent mixtures studied, the resulting complex is enthalpy stabilized but entropy destabilized. Finally, the experimental results were compared with theoretical ones that were obtained from molecular modeling methods. Based on our results, it is most probable that Li⁺-15C5 in solvent stays in a rather nesting complex form with greater LogK_f values, but Na⁺-15C5 forms a complete perching complex form with lower LogK_f values.     

Rotational analysis of the a3Π0+,1-X1Σ+ emission systems of GeH+

New emission systems have been observed from the helium afterglow reaction of GeH₄ in the 520–610 nm region. On the basis of the rotational analysis, they were assigned to the a ³Π_0⁺-X¹Σ⁺ and a³Π₁-X¹Σ⁺ subsystems of GeH⁺. Spectroscopic constants have been determined for the GeH⁺ (a³Π_0⁺, a³Π₁, X¹Σ⁺) states.     

Asymmetric Mixed‐Valence Complexes that Consist of Cyclometalated Ruthenium and Ferrocene: Synthesis,Characterization, and Electronic‐Coupling Studies

Three bis‐tridentate ferrocene‐containing cyclometalated ruthenium complexes, [(Fcdpb)Ru(tpy)]⁺ ( 1 ⁺), [(Fctpy)Ru(dpb)]⁺ ( 2 ⁺), and [(Fcdpb)Ru(Fctpy)]⁺ ( 3 ⁺), have been prepared and characterized, where Fcdpb is the 2‐deprotonated form of 1,3‐di(2‐pyridyl)‐5‐ferrocenylbenzene, tpy is 2,2′:6′,2“‐terpyridine, dpb is the 2‐deprotonated form of 1,3‐di(2‐pyridyl)benzene, and Fctpy is 4′‐ferrocenyl‐2,2′:6′,2”‐terpyridine. Single crystals of compounds 2 ⁺ and 3 ⁺ have been studied by X‐ray analysis. Complexes 1 ⁺ and 2 ⁺ displayed two anodic redox waves, whilst three well‐separated redox couples were observed for compound 3 ⁺. A combined experimental and computational study suggested that the ferrocene unit on the Fcdpb moiety in compounds 1 ⁺ and 3 ⁺ was oxidized first. In contrast, the order of the oxidation of ruthenium and ferrocene in complex 2 ⁺ was reversed. Metal‐to‐metal‐charge‐transfer transitions (MM′CT) have been observed for the singly oxidized states 1 ²⁺, 2 ²⁺, and 3 ²⁺ in the near‐infrared region. Hush analysis showed that the metal–metal electronic couplings in compounds 1 ²⁺ and 3 ²⁺ were much stronger than those in compound 2 ²⁺.     

Synthesis of Cationic R2P5+ Cages and Subsequent Chalcogenation Reactions

Cationic R₂P₅⁺ cage compounds ( 1 ⁺) have been synthesized by the stoichiometric reaction of R₂PCl, GaCl₃ and P₄. The reaction conditions depend on the substituent R. Alkyl‐substituted derivatives ( 1 a – 1 d [GaCl₄]) are best synthesized under solvent‐free conditions, whereas aryl‐substituted derivatives ( 1 e – 1 h [GaCl₄]) are formed in C₆H₅F. All compounds have been prepared on a multi‐gram scale in good to excellent yields and have been fully characterized with an emphasis on ³¹P NMR spectroscopy in solution and single‐crystal structure determination. Subsequent chalcogenation reactions of cations R₂P₅⁺ ( 1 a ⁺, 1 e ⁺) and trication Ph₆P₇³⁺ ( 3 ³⁺) with elemental sulfur (α‐S₈) or grey selenium (Se_grey) yielded a series of unique polyphosphorus–chalcogen cations ( 4 a ⁺, 4 e ⁺, 5 a ⁺, 6 ²⁺ and 7 ²⁺), possessing nortricyclane‐type molecular structures. An in‐depth study of the ³¹P{¹H} and ⁷⁷Se NMR spectroscopic parameters is presented, and correlations between the substitution pattern and the observed structural features have been investigated in detail.     

Photoionization and Dissociation Study of 2-Methyl-2-propen-1-ol: Experimental and Theoretical Insights

The photoionization and dissociation of 2-methyl-2-propen-1-ol (MPO) have been investigated by using molecular beam experimental apparatus with tunable vacuum ultravioletsynchrotron radiation in the photon energy region of 8.0-15.5 eV. The photoionization efficiency (PIE) curves for molecule ion and fragment ions: C₄H₈O⁺、C₄H₇O⁺、C₃H₅O⁺、C₄H₇⁺、C₄H₆⁺、C₄H₅⁺、C₂H₄O⁺、C₂H₃O⁺、C₃H₆⁺、C₃H₅⁺、C₃H₃⁺、CH₃O⁺、CHO⁺ have been measured, and the ionization energy (IE) and the appearance energies (AEs) of the fragment ions have been obtained. The stable species and the first order saddle points have been calculated on the CCSD(T)/cc-pvTZ//B3LYP/6-31+G(d,p) level. With combination of theoretical and experimental results, the dissociative photoionization pathways of 2-methyl-2-propen-1-ol are proposed. Hydrogen migrations within the molecule are the dominant processes in most of the fragmentation pathways of MPO.     

Reaction of 2-hydroxyethylhydrazine with a trifluoromethyl-β-diketone: Study and structural characterization of a new 5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazole intermediate

The reaction of the β-diketone 4,4,4-trifluoro-1-pyridin-2-yl-butane-1,3-dione and the monosubstituted hydrazine 2-hydroxyethylhydrazine has been investigated. Two products have been identified, 2-(2-hydroxyethyl)-3-pyridin-2-yl-5-trifluoromethyl-4,5-dihydropyrazole (P) and 2-(3-pyridin-2-yl-5-trifluoromethylpyrazol-1-yl)ethanol (L) in proportion 2:8, when the reaction was done at room temperature in ethanol for 15 h. The preparation of P as a pure product was performed in ethanol at 0 °C for 7 h. P has been characterized by ¹H, ¹³C{¹H} and ¹⁹F{¹H} NMR spectroscopy and by other techniques as appropriate.     

Anion Cryptates: Synthesis,Crystal Structures,and Complexation Constants of Fluoride and Chloride Inclusion Complexes of Polyammonium Macrobicyclic Ligands

Three macrobicyclic octamines 1–3 and the macrotricyclic hexadecamine 14 have been synthesized. The octamines 1–3 bind anionic substrates when protonated. The stability constants of the complexes between the protonated forms of the macrobicyclic polyamines and halide anions have been determined by pH-metric measurements. The stability constants in H₂O are very high; 1 in its hexaprotonated form binds F⁻ with high selectivity (selectivity F⁻/Cl⁻ > 10⁸), while 3 exhibits strong stability constants for both F⁻ and Cl⁻. Three X-ray structures have been obtained, one where F⁻ is held inside the cavity of 1 · 6H⁺, one where Cl⁻ is included in 3 · 6H⁺, and 3 · 6H⁺ where the cavity is empty.     

Synthesis of trifluoromethyltriazoles from trifluoroacetohydrazonoyl bromide

N-Phenyltrifluoroacetohydrazonoyl bromide ( 1 ) reacted with potassium isothiocyanate and isocyanate to give 5-imino-4-phenyl-2-trifluoromethyl-δ²-1,3,4-thiadiazoline and 1-phenyl-3-trifluoromethyl-δ²-1,2,4-triazolin-5-one, respectively. On treatment with several types of cumulative double bonds such as alkyl isothiocyanate, isocyanate, and carbodiimide, 1 afforded regioselectively the corresponding trifluoromethylthiadiazoline, -oxadiazoline, and -triazoline, respectively. These cycloadducts were assumed to form through the stepwise path involving the addition of 1 toward the cumulative double bond followed by the intramolecular cyclization. Concerning cyanamides, the corresponding triazoles were obtained and the reactions with pyridines afforded the triazolopyridinium bromides. The reactivity of the latter was found to depend on the substituents on the pyridine nucleus.     

Electrophilic trifluoromethylation of arenes and N-heteroarenes using hypervalent iodine reagents

The reaction of hypervalent iodine trifluoromethylating reagents with a variety of arenes and N-heteroarenes gives access to the corresponding trifluoromethylated compounds. In comparative studies, 1-trifluoromethyl-1,3-dihydro-3,3-dimethyl-1,2-benziodoxole (2) proved to be the superior to 1-trifluoromethyl-1,2-benziodoxol-3-(¹H)-one (1) for the direct aromatic trifluoromethylation. Depending on the individual substrates, additives such as zinc bis(trifluoromethylsulfonyl)imide or tris(trimethylsilyl)silyl chloride proved helpful in promoting the reactions. In the case of nitrogen heterocycles a pronounced tendency for the incorporation of the trifluoromethyl group at the position adjacent to nitrogen was observed.     

The first synthesis and X-ray structures of polyfluorinated 1,2-, 2,3- and 2,4a-dihydro-1,3-diazafluorenes

Acetic acid-catalyzed condensation of 2-amino-3-(1-imino-2,2,2-trifluoroethyl)-1,1,4,5,6,7-hexafluoroindene (1b) with acetone and cyclopentanone gives 5,6,7,8,9,9-hexafluoro-2,2-dimethyl-4-trifluoromethyl-2,3-dihydro-1,3-diazafluorene (2a) and 5,6,7,8,9,9-hexafluoro-4-trifluoromethyl-2,3-dihydro-1,3-diazafluorene-2-spiro-1′-cyclopentane (3a) together with small amounts of 5,6,7,8,9,9-hexafluoro-2,2-dimethyl-4-trifluoromethyl-1,2-dihydro-1,3-diazafluorene (2b) and 5,6,7,8,9,9-hexafluoro-4-trifluoromethyl-1,2-dihydro-1,3-diazafluorene-2-spiro-1′-cyclopentane (3b), respectively. When acted upon by (CH₃)₂SO₄ compounds 2, 3 were converted into corresponding fluorine-containing 1-methyl-1,2-dihydro-1,3-diazafluorenes 6, 7. 4a-Chloro-5,6,7,8,9,9-hexafluoro-2,2-dimethyl-4-trifluoromethyl-2,4a-dihydro-1,3-diazafluorene (8) has been synthesized by the interaction of compound 2 with SOCl₂. Solution of compound 2 as well as 8 in CF₃SO₃H-CD₂Cl₂ generated 5,6,7,8,9,9-hexafluoro-2,2-dimethyl-4-trifluoromethyl-1,2,3,4-tetrahydro-1,3-diazafluorene-4-yl cation (2c). The structures of compounds 2, 3, 6-8 have been determined by single crystal X-ray diffraction.     

Cyclocondensation between fatty acid hydrazides and 1,1,1-trifluoro-4-alkoxy-3-alken-2-ones: Introducing a trifluoromethylated head onto fatty acid moieties

This paper reports the regioselective synthesis of new trifluoromethylated lipid derivatives, namely, 1-(5-hydroxy-5-trifluoromethyl-3-alkyl-4,5-dihydro-1H-pyrazol-1-yl)alkan-1-ones, through cyclocondensation reactions between a series of fatty hydrazides (palmitoyl, stearoyl, and oleoyl hydrazides) obtained from fatty acids from renewable resources (1,1,1-trifluoro-4-alkoxy-3-alken-2-ones [F₃CC(O)CH?C(R¹)OR, where R¹?=?H and R?Et; R¹?=?–(CH₂)₆CH₃, –(CH₂)₆CH₃, –(CH₂)₈CH₃, –(CH₂)₉CH₃, –(CH₂)₁₀CH₃, –(CH₂)₁₂CH₃, –(CH₂)₂Ph], and R?Me). Experimental observations showed that the lipophilic characteristic of 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-pyrazoles (5–7) prevent the acid catalyzed dehydration to aromatization of 1H-pyrazole ring, although in some cyclocondensations a proportion of the aromatic derivative 1-(5-trifluoromethyl-3-alkyl-1H-pyrazol-1-yl)alkan-1-one was obtained. All products were characterized using multinuclear (¹H, ¹³C, ¹⁹F) NMR spectroscopy.     

Synthesis of Some 2-(3-Alkyl/aryl-5-trifluoromethylpyrazol-1-yl)-4-(coumarin-3-yl)thiazoles as Novel Antibacterial Agents

Abstract

Herein, we describe a one-pot synthesis of some novel 2-(3-alkyl/aryl-5-trifluoromethylpyrazol-1-yl)-4-(coumarin-3-yl)thiazoles (6) involving the reaction of 3-alkyl/aryl-5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazole-1-thiocarboxamides (3) with 3-bromoacetylcoumarins (5) in the presence of sodium carbonate in ethanol. Reaction of 3 with 5 in the absence of sodium carbonate, however, resulted in the formation of 2-(3-alkyl/aryl-5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazol-1-yl)-4-(coumarin-3-yl)thiazoles, which were subsequently dehydrated to 6 by refluxing in ethanol in the presence of sodium carbonate. The structure of the synthesized compounds (6) was confirmed by infrared (IR), mass, ¹H NMR, and ¹³C NMR spectra and elemental analysis data. Newly synthesized compounds (6) showed moderate to good activity against Gram-positive bacteria.     

Raman and resonance-Raman spectra of CsI/I−3

Raman and resonance-Raman spectra of the I^?₃ ion isolated within CsI crystals have been studied using 647 nm and 488 nm exciting radiation. Sample temperatures between 300 and 20 K have been used. Eleven overtones of the symmetric stretching mode (nν₁) have been observed in the resonance-Raman spectrum excited by the 488 nm Ar⁺ laser line. Bands centred at 153, 170, 264 and 304 cm^?1 have been assigned as ν₃, 2ν₂, ν₁+ν₃ and 2ν₃(Σ⁺) respectively. The remaining structure between the nν₁ lines has been assigned as due to combinations of these lines with the lattice vibrations of the CsI crystal.     

Extraction of microamounts of yttrium from water into nitrobenzene using hydrogen dicarbollylcobaltate in the presence of 15-crown-5

Summary Extraction of microamounts of yttrium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B^-) in the presence of 15-crown-5 (15C5,L) has been investigated. The equilibrium data have been explained assuming that the complexes HL⁺, HL_2,⁺, YL³⁺, YL_2,³⁺and YH_-1L_2,²⁺are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined.     

Infrared and paH correlation of proton transfer in and bridges in acetonitrile

Hydrogen bond complexing (BHB)⁺ between N-bases and their cations has been examined by infrared spectroscopy and potentiometry. In the acetonitrile (AN) solution there have been studied hetero-systems (B + B₁H⁺), where the differing bases, B, may be triethylamine, N-methylpiperidine, morpholine, N-methylimidazole, pyridine, 2- and 3-chloropyridine, quinoline and trimethyl-N-oxide with B₁H⁺ : trimethyl-N-oxideH⁺ and N-methylimidazoleH⁺. Homocomplex (Me₃NO)₂H⁺ has been distinguished. In the H-bridges cation the stretching band ν_s (NH⁺) and (−OH⁺) are dependent directly on the p_aH and formation constant K_f of the component bases.     

Kinetic modeling of the reactions of C3H3+ with acetylene,deuteroacetylene, and diacetylene

The reactions of ?-C₃H₃⁺ (propargylium cation) with acetylene and diacetylene have been modeled kinetically. Data were obtained from Fourier Transform Ion Cyclotron Resonance (FTICR) experiments on these systems, which are themselves models for soot particle initiation. Acetylene forms an encounter complex with ?-C₃H₃⁺, but, in the absence of a third body collision, the complex decomposes to acetylene and c-C₃H₃⁺ (cyclopropenylium cation) at about 1/3 the rate it decomposes to acetylene and ?-C₃H₃⁺, in spite of the fact that c-C₃H₃⁺ is ca. 115 kJ/mol more stable than ?-C₃H₃⁺. The encounter complex is long enough lived, and energetic enough, to scramble deuterium in reactions between ?-C₃H₃⁺ and C₂D₂. These reactions have been successfully modeled, yielding a nearly statistical distribution of deuterium, and a rather large kinetic isotope effect. The more complex reactions of ?-C₃H₃⁺ with diacetylene have also been modeled.