Adamantylation of β-dicarbonyl compounds

Reactions of adamantan-1-ol with β-dicarbonyl compounds in 1,2-dichloroethane in the presence of In(OTf)₃, Ga(OTf)₃, Sc(OTf)₃, or Cu(OTf)₂ give the corresponding adamantylated derivatives in 45–93% yields.     

Molecular structure of diatomic lanthanide compounds

The molecular constants of selected diatomic lanthanide compounds (LaH, LaO, LaF, EuH, EuO, EuF, EuS, GdO, GdF, GdH, YbH, YbO, YbF, YbS, LuH, LuO and LuF) have been calculated by using relativistic small-core pseudopotentials and optimized (14s13p10d8f6g)/ [6s6p5d4f3g] valence basis sets. The results are in good agreement with available experimental data, with exception of YbO and LuF. The reasons for the discrepancies in case of YbO are due to a complicated mixing of configurations in the ground state, whereas in case of LuF the binding energy estimated by experimentalists appears to be too low.     

Sulfoxide-mediated α-arylation of carbonyl compounds

A novel sulfoxide-mediated α-arylation of carbonyl compounds is reported. This reaction proceeds under very mild conditions at room temperature and does not require any transition-metal promoter or catalyst.     

Synthesis of a new series of anti-rhinovirus compounds

The synthesis of a series of 3,6-dichloropyridazine derivatives was described.In vitro experiment,all compounds exhibited ananti-rhinovirus activity,and one of the compounds 6g showed the comparable activity as our lead compound pirodavir.     

Conformational study of α-phenylthiocarbonyl compounds

Electrical and electrooptical characteristics of-phenylthioacetone,-phenylthiocyclohexanone, and-phenylthio-4-caranone have been determined and used in establishing the structure of the compounds in solution. It has been shown that the preferred conformer with respect to the bond , is the ac-conformer [(O=C-C-S)>90°], in which the gauche conformer with respect to the C-S bond is realized, with a 1,3-parallel position of the C=O and S-Ph bonds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2483–2488, November, 1991.     

Regioselective synthesis of linalyl compounds via addition reaction of geranyl bromide and tin with carbonyl compounds

Linalyl alkyl or aryl carbinols were regioselectively synthesized by the reaction ofgeranyl bromide and powdered tin with aldehydes and ketones.     

Reactions of cyanofurazans with β-dicarbonyl compounds

In the presence of nickel acetylacetonate, -dicarbonyl compounds readily add at the nitrile group of 4-R-3-cyanofurazans to form enaminofurazans. The adducts obtained from 4-amino-3-cyanofurazan underwent intramolecular cyclization on heating with AcOH in EtOH to give furazano[3,4-b]pyridine derivatives in high yields.     

Synthesis of α-functional nitro compounds by the nitration of activated carbonyl compounds in a two-phase system

2-Nitro-1,3-dicarbonyl and -nitromonocarbonyl compounds were synthesized in the yields varying from moderate (30 %) to nearly quantitative by the nitration of -dicarbonyl compounds in a two-phase system: sulfuric/nitric acid mixture-chloroform at - 10÷10 °C. The use of phase transfer conditions made it possible to avoid the formation of furoxans as by-products and to simplify the isolation of products. This method is quite common for preparing various -functional nitro compounds including those containing a CF₃-group. Key words: nitration, -functional nitro compounds.Translated fromIzvestiya Akademn Nauk. Seriya Khimicheskaya, No. 1, pp. 76–79, January, 1994.     

O−• chemical ionization of carbonyl compounds

The negative ion chemical ionization mass spectra of twentyeight C₄ to C₇ carbonyl compounds were recorded using the oxide radical anion O^?? as reagent ion. As noted earlier, the reactions occurring include H⁺ abstraction, H ₂ ^+? abstraction, H? atom displacement, and alkyl radical displacement. In addition, the [M?2H]^? ions fragment further by alkyl radical elimination. The relative importance of these reactions depends strongly on molecular structure, with the result that isomer distinction frequently is possible. Where this is not possible, as for isomeric aldehydes, the collisional charge inversion mass spectra of common product ions provides isomer distinction. The H ₂ ^+? abstraction reaction is shown to involve abstraction not only of two hydrogens from the same α-carbon but also, in part, abstraction of one hydrogen from each α-carbon.     

Synthesis and properties of trifluoromethylating steroid compounds

Trifluoromethyl steroids la,b; 2a,b; 3a,b have been synthesized by starting from estren 3,17-dicarbonyl-3,3-dimethyl ether (4) and dl-18-methyl-2(3)l5(10)-estra-diene-17-carbonyl-3-methyl ether (5),and by using trimthyltrifluoromethylsilane as the trifluoromethylating agent under the catalysis of tetrarnethylam-monium fluoride.The overall yields were 82%,76%; 54%,62%; and 27%,25%,respectively The α-configura tion of trifluoromethyl group of 17-position was determined by X-ray crystal diffraction method Compounds 1a,2a and 3a showed high affinity for rat uterus PRc.The test of biological activities of compounds 1b,2b and 3b is proceeding.     

Effect of alkanolamines on properties of epoxy–anhydride compounds

Hot-cured epoxy compound based on ED-20 resin and isomethyltetrahydrophthalic anhydride was modified with alkanolamines of different structures. The influence exerted by the structure of alkanolamines on the structure and operation characteristics of modified epoxy–anhydride compounds was examined. Introduction of alkanolamines decreases the gel and cure times and enhances the operation properties of cured epoxy–anhydride compounds. The best products were obtained with alkanolamines derived from ethylenediamine. Their introduction into epoxy–anhydride compounds enhances by a factor of 1.5–2 the elasticity, tensile strength at uniform extension, and impact resilience of the cured formulations.     

Studies on organophosphorus compounds 52.Structure-reactivity studies of organophosphorus compounds by MNDO calculations

MNDO and MM2(85)methods were used to study the conformation and the structure-reactivity relationship of neutral and acidic phosphorus esters.The calculation results indicate thatfor the most stable conformation,the charge density of phosphoryl oxygen(q_O)is determined notonly by the electronegativity of the substituents,but also by the conformation of the alkoxyl groupson the phosphorus atom.Meanwhile,the conformation of the alkoxyl group provides,as a rule,more important influence on the charge density of the phosphoryl oxygen.However,the energy ofthe highest occupied molecular orbital(EHOMO)is basically dependent on the eletronegativity of thesubstituents,while the donating ability or the withdrawing ability of the neutral phosphorus com-pounds is mainly governed by the EHOMO but not the q_O.This is also true for other kinds of theneutral oxygen-containing compounds.     

Kinetics of the radical scavenging activity of β-carotene-related compounds

To clarify the non-enzymatic radical-scavenging activity of β-carotene-related compounds and other polyenes, we used differential scanning calorimetry to study the kinetics of radical polymerization of methyl methacrylate (MMA) by 2,2′-azobisisobutyronitrile (AIBN) or benzoyl peroxide (BPO) in the absence or presence of polyenes under nearly anaerobic conditions at 70°C, and analyzed the results with an SAR approach. The polyenes studied were all-trans retinol, retinol palmitate, calciferol, β-carotene and lycopene. Polyenes produced a small induction period. The stoichiometric factor (n) (i.e. the number of radicals trapped by each inhibitor molecule) of polyenes was close to 0. Tetraterpenes (β-carotene, lycopene) suppressed significantly more of the initial rate of polymerization (R ^inh) than did diterpenes (retinol, retinol palmitate). The inhibition rate constants (k ^inh) for the reaction of β-carotene with AIBN-or BPO-derived radicals were determined to be 1.2–1.6?×?10⁵ l?/?mol?s, similar to published values. A linear relationship between k ^inh and the kinetic chain length (KCL) for polyenes was observed; as k ^inh increased, KCL decreased. KCL also decreased significantly as the number of conjugated double bonds in the polyenes increased. Polyenes, particularly β-carotene and lycopene, acted as interceptors of growing poly-MMA radicals.     

Characterisation of flavour compounds formed by γ-irradiation of polypropylene

Sterilisation of plastic packaging materials for food, pharmaceutical or cosmetic products with ⁶⁰Co γ-irradiation in the presence of oxygen can result in the formation of volatile substances. These may subsequently induce off-odours in these materials that might be regarded as negative by the consumers. Trace volatiles and odorous substances of polypropylene, irradiated with ⁶⁰Co γ rays at 10 and 20 kGy, respectively, were collected and analysed by gas chromatography–olfactometry (GC–O), GC–MS and GC–GC–MS. The methodology was successfully applied for identification of 29 characteristic odorants in a non-irradiated control sample and 38 odorants in γ-irradiated polypropylene samples. Selected odour-active compounds were quantified using GC–GC–MS in combination with stable isotope dilution assays. The quantitative data mirrors the compositional changes in volatile odorous substances from polypropylene during treatment with ionising γ rays in a ⁶⁰Co-irradiation plant.     

Reactions of 1,2-diaminobenzimidazoles with β-dicarbonyl compounds

The reactions of 1,2-diaminobenzimidazoles with β-dicarbonyl compounds give 1,2,4-triazepino [2,3-a]benzimidazole and pyrimido [1,2-a]benzimidazole-derivatives.     

Dielectric properties of three‐ring fluorinated compounds

Four three‐ring compounds, consisting of two cyclohexyl rings and one mono‐ or difluorinated phenyl ring, were studied using dielectric spectroscopy methods over a broad frequency range (1 kHz–3 GHz). They exhibit a nematic phase in a broad temperature interval, enriched by a smectic B phase in one case. The static and dynamic dielectric properties were analysed. It was established that the bridging CH₂CH₂ group placed between cyclohexyl and phenyl rings considerably changes the reference frame of the molecule, unlike the situation when it links two cyclohexyl rings. In the nematic and smectic B phases the motion around the short axis is a Debye process, whereas the rotation around the long axis is split into two processes: independent rotation of the whole molecule and its fluorophenyl part.     

α-thiocyanation of carbonyl compounds: A review

The α-thiocyanation of carbonyl compounds is one of the most important processes in synthetic organic chemistry. These compounds are important precursors for the production of various biologically important heterocyclic compounds and other industrially important products. Ammonium thiocyanate (NH₄SCN) is a key reagent for the production of such a class of thiocyanate intermediates. In addition to the inherent efficiency issues, there are also environmental concerns that need to be addressed. Therefore, in recent years considerable advances have been made for the synthesis of α-thiocyanation of carbonyl compounds with high selectivity and yield. In this review, we have summarized various methods for the synthesis of α-thiocyanation carbonyl compounds.     

Some reactions of fluorosulfonyldifluoroacetic acid with N-heterocyclic compounds

Difluorocarbene generated from the decomposition of fluorosulfonyldifluoroacetic acid (2)reacted with various sodium salts of N-heterocyclic compounds(1) giving the corresponding difluoro-methylated products in acetonitrile at 10—40℃.Benzotriazole(1a),benzimidazole(1b) and imidazole(1c) were converted into 1-(difluoromethyl)benzotriazole(3a),1-(difluoromethyl)benzimidazole(3b) and1-(difluoromethyl)imidazole(3c)respectively.Indole(1d)reacted with 2 to give -(fluorosulfonyldifluoro-acetate)indole(2d) rather than the expected difluoromethylated derivatives.