Ring opening of aziridines with tetranitromethane in the presence of triethylamine. Efficient synthesis of β-tosylamino nitrates

A convenient method for the preparation of β-tosylamino nitrates based on the ring-opening reaction of aziridines by tetranitromethane in the presence of triethylamine is described. A series of substituted β-amino nitrates is obtained in high yields under mild conditions.     

Synthesis and properties of thiazole halohydrazones. 1. Synthesis and interaction of 2-α-chlorobenzylidenehydrazino-4-ethoxycar-bonyl-thiazole with triethylamine in the presence of dipolarophiles

In the interaction of 2--chlorobenzylidenehydrazino-4-ethoxycarbonylthiazole with triethylamine, a nitrilimine is formed as an intermediate that does not react with dipolarophiles, but rather undergoes intramolecular 1, 5-dipolar cyclization to form 3-phenyl-5-ethoxycarbonylthiazolo[2,3-c]-1,2,4-ttiazole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, 253–255, February, 1994. Original article submitted November 30, 1993.     

β-Aminoselenenation of alkenes with arylselenenamides in the presence of sulfamic acid

Russian Chemical Bulletin -     

Synthesis of SAPO-34 using metakaolin in the presence of β-cyclodextrin

SAPO-34 molecular sieves were synthesized by the addition of β-cyclodextrin(β-CD) as crystal growth inhibitor using metakaolin as silicon and aluminum sources. Properties of the obtained samples were characterized by XRD,SEM,N2adsorption–desorption,FTIR,XRF,EDX,NH293-TPD andSi MAS NMR. When β-CD was added,crystal size of the SAPO-34 crystals decreased. Variation of Si content from the crystal center to surface decreased while total Si content hardly changed.29 Si MAS NMR results showed that β-CD contributed to better Si dispersion and decreased the size of Si(4Si) patches. Moreover,the MTO(methanol-to-olefin) process was conducted to investigate the influence of β-CD on catalytic performance. The synthesized sample with molar ratio of β-CD/Al2O3 equaling 0.055 remained active for 610 min while the sample synthesized without β-CD for only 280 min,which indicates that the lifetime of catalyst synthesized with β-CD is greatly prolonged.     

The reaction of perhalofluoroalkanes with sodium hydrogen sulfite or sodium dithionite in the presence of triethylamine

Hydrodehalogenation or hydrosulfonate-dehalogenation products, hydrohalofluoro-carbons or 2-hydropolyhalofluoroalkanesulfonates, were formed respectively from the title reaction under mild condition in good yield.     

Reactions of areneselenenamides with alkenes in the presence of phosphorus(V) and sulfur(IV) oxyhalides. New synthesis of β-haloalkyl selenides

A new procedure was proposed for activation of areneselenenamides with phosphorus(V) and sulfur(IV) oxyhalides. According to the ¹H, ¹³C, and ³¹P NMR data, areneselenenamide reacts with phosphorus oxyhalide to form intermediate adduct in which the phosphorus atom is coordinated at the selenium. Areneselenenamides activated by phosphorus(V) oxyhalides react with alkenes (norbornene and norbornadiene) with high trans-stereoselectivity. Their reactions with terminal olefins are regioselective, and they lead to preferential formation of the corresponding Markovnikov adducts.     

Diels-Alder reaction with phosphaalkenes. Synthesis of functionalized λ3 phosphabenzenes.

The reaction of phosphaalkenes (1 and2) with 1,3 dienes such as methyl sorbate and 1-methoxy 3-trimethylsilyloxy-1,3 butadiene leads to functionalized λ³ phosphabenzenes6,9,12,13 and16 after aromatization of the primary adducts. The aromatization may occur either spontaneously or after chemical transformations. The reversible cycloaddition has allowed the synthesis of isomeric phosphabenzenes6 and9. Diels-Alder reaction with phosphaalkenes appears to be a general method for the obtention of functionalized λ³ phosphabenzenes.     

Oxidation of β-dicarbonyl compounds with tert-butyl hydroperoxide in the presence of vanadyl acetylacetonate

Oxidation of β-dicarbonyl compounds with tert-butyl hydroperoxide in the presence of vanadyl acetylacetonate (benzene, 20°C) involves the activated methylene group with intermediate formation of trioxo derivatives and is accompanied by decomposition of carbon skeleton. The oxidation products are carbon dioxide, carboxylic acids, and tert-butyl and peroxy esters derived from the latter.     

Reaction of Polyfluorinated β-Diimines with Ketones. A Novel Method for the Synthesis of Fluorinated Pyridines

Reaction of polyfluorinated -diimines with ketones gave polyfluorinated pyridines     

Synthesis of enantiopure β-azidoalcohols from their ketoazides by reduction with NaBH4 in the presence of alumina and in situ lipase resolution

An enantioselective synthesis of chiral β-azidoalcohols via the reduction of the corresponding ketoazides with NaBH₄ in the presence of moist aluminium oxide followed by an in situ lipase-mediated resolution is described. The efficiency of various lipases and the effect of solvents have also been studied for this method. The excellent results obtained under mild reaction conditions, indicates its applicability and importance over classical methods previously reported.     

Thermodynamic denaturation of β-lactoglobulin in the presence of cetylpyridinium chloride

In this work, we determined the stability parameters of bovine β-lactoglobulin, variant A, (BLG-A), in relation to their transition curves induced by cetylpyridinium chloride (CPC) as a cationic surfactant. The experiments took place over the temperature range of 298 K to 358 K. For each transition curve at any specific temperature, the conventional method of analysis, which assumes a linear concentration dependence of the pre- and post-transition base lines, gave the most realistic values for ΔG_D(H₂O). Results show that the minimum value of ΔG_D(H₂O) occurs at T = 328 K. Using the Gibbs–Helmholtz equation, the values of enthalpy, ΔH_D, and entropy, ΔS_D, of denaturation have been calculated considering temperature dependence of ΔG_D at any specified concentration of CPC. The values of 12.05 kJ · mol⁻¹, 18.54 kJ · mol⁻¹, and 18.32 J · mol⁻¹ · K⁻¹, were obtained for ΔG_D(H₂O), ΔH_D(H₂O), and ΔS_D(H₂O), respectively. The results show that the enthalpy term dominates the entropy term.     

Synthesis ofβ-glycosides of n-acetylglucosamine in the presence of HgI2

The use of HgI₂ as catalyst in the synthesis oftrans-glycosides of N-acetylglucosamine is described. Using this catalyst, -glycosides of N-acetylglucosamine with aglycons of different structures and lyophilicities have been synthesized. The possibility of performing oligosaccharide synthesis has been demonstrated.     

Crystallization of post-consumer polypropylene in the presence of β-nucleating agent

Journal of Thermal Analysis and Calorimetry - In this paper, the heat transfer characteristics of the nanofluid through a parallel plate soft nanochannel are investigated under the fully developed...     

Kinetics of peroxidase-catalyzed oxidation of quercetin in the presence of β-cyclodextrin

It is established that the rate of peroxidase-catalyzed oxidation of flavonoid quercetin is increased by 20% in the presence of macrocyclic complexing agent β-cyclodextrin. The comparison of the kinetic parameters of the indicated reaction in the presence and in the absence of β-cyclodextrin shows that its introduction does not significantly influence the specificity of the enzyme with respect to the reducing substrate (characterized as k _cat/K _M ratio), while the increase in the reaction rate does not depend on the duration of the incubation of quercetin with β-cyclodextrin. It is assumed that the increase of the reaction rate is associated with nonspecific interaction between β-cyclodextrin and quercetin oxidation product.     

The Reaction of β-Aminoenones with Cyanamide. A High Efficient Synthesis of 2-Aminopyrimidines

β-aminoenones react with cyanamide, molar ratio 1:2, to yield 2-aminopyrimidines in nearly quantitative yields.     

A novel synthesis of β-lactone precursors of pyramidalized alkenes

β-Lactone precursors 11 and 12 of pyramidalized alkenes 3,n = 1and 2, have been synthesized by a two-step route involving transannular Paterno-Buchi reaction of methyleneketones 7 and 8, followed by RuO₄ oxidation of the resulting oxetanes 9 and 10. Evidence for the formation of alkene 3,n = 2, by pyrolysis of 12 is presented.     

Direct synthesis of carbonyl compounds from THP ethers with IBX in the presence of β-cyclodextrin in water

Water, an environmentally friendly reaction medium, has been utilized for the oxidative deprotection of tetrahydropyranyl ethers 1 with IBX at room temperature in the presence of β-cyclodextrin to give the corresponding carbonyl compounds 2.     

The β-Methoxyethoxymethyl Protecting Group in Alkaloid Synthesis. Synthesis of Abresoline

The isolation of abresoline (1), the only seco-Lythraceae alkaloid, is one of the few pieces of evidence for the proposed oxidative coupling pathway for the biosynthesis of the Type I Lythraceae alkaloids.¹ We required compound 2 for our study of oxidative ary1 coupling as a synthetic route to these alkaloids. The similarity between 1 and 2 prompted the investigation of the synthesis of abresoline as a model for the preparation of 2 and related compounds.     

Alkylation of phenol by β-pinene in the presence of aluminum phenolate

The alkylation of phenol by β-pinene using Al(OPh)₃ as a catalyst was studied. It was found that the composition of the products depended on the ratio of starting materials. The principal products were chromane-type ethers with an equimolar ratio of starting materials and an excess of phenol. ortho-Alkylated phenol and an ether with a terpene substituent of bornyl structure were formed with a two-fold excess of β-pinene.     

Spectrofluorimetric study and determination of desipramine in the presence of β-cyclodextrin

The native fluorescence intensity of desipramine was enhanced in the presence of β-cyclodextrin in aqueous solution. The inclusion complex formation between these compounds was studied by spectrofluorimetry. A stable complex with a 2: 1 stoichiometry of β-cyclodextrin to desipramine was formed (logβ₂ = 9.29 ± 0.01). In the presence of an optimum concentration of β-cyclodextrin, the fluorescence intensity was linearly proportional to desipramine concentration in the range of 0.1–100 μg/mL (7.2 × 10^?7?1.0 × 10^?4 M) with a limit of detection of 7 × 10^?8 M. The method was successfully applied to the detection of desipramine in its tablets.