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Alkylation or arylation of selenide or diselenide anions is a well-established method to obtain organoselenium compounds. Nevertheless, detecting inorganic selenium anions using 77Se NMR is still a challenge. In a previous work, alkylation of Na2Se was found sometimes to yield a mixture of organyl selenides/diselenides in variable amounts. In the literature, this mixture is sometimes attributed to the oxidation of an intermediate alkyl selenol during the extraction. To understand this process, a series of experiments using 77Se NMR were performed. It was clear from the 77Se NMR experiments that NaHSe− and S e 2 2 − formation was very dependent on the NaBH4 stoichiometry used. After alkylation, alkyl selenol and dialkyl diselenide were identified, proving they were not formed during the extraction step. As a result, alkyl selenols, dialkyl selenides or dialkyl diselenides with a high purity degree were obtained. To achieve high purity and selectivity of the organoselenium compound, the stoichiometric ratio between Se0/NaBH4 has to be carefully measured.

The cetane number (CN) is one of the most important parameters regarding diesel fuel oil quality, mainly ignition properties. Traditionally, the CN determination is performed by a quite laborious and high-cost method on an explosion engine. On the other hand, nuclear magnetic resonance (NMR) spectroscopy is increasing as a versatile tool for quality control in several areas, such as petroleum and fuels, which permits the fast and direct investigation on samples. In this work, two NMR-based methods for CN determination based on multivariate calibration were developed with advantages of time saving, without the need of any sample treatment.

The tellurium nuclear magnetic resonance spectrum of chiral tellurium ferrocene 2 produces a single signal at different chemical shifts when solubilized together with different enantiomeric proportions of chiral compounds.

A series of common organometallic reagents were used in the reaction with an acyclic and a cyclic activated 2-alkenyl aziridines and the selectivity aspects for each aziridine was addressed.

This paper describes the preparation of a series of oxazoline cuprates by reaction of an oxazoline lithium anion with copper(I) salts: CuBr.DMS, Cul and CuCN in THF solution. The oxazoline cyanocuprate showed the best reactivity using enones as electrophiles.

Current studies of oxazoline cyanocuprates addition to conjugated nitroalkenes, and their improved reactivity when compared to lithium oxazoline anions, has shown to be an efficient method for the synthesis of a variety of γ-nitrooxazolines, an interesting intermediate of γ-amino acids.

The organic composition and organic-inorganic interaction in paper mill sludge (PS) solvent extracts (hexane, ethyl acetate, acetone and ethanol) and humic fractions, humic acid (HA) and humin (HU) were studied by electron paramagnetic resonance spectroscopy (EPR), proton and carbon-13 nuclear magnetic resonance spectroscopy ( 1 H NMR; 13 C NMR), Fourier-transformed infrared spectroscopy (FTIR), and ultraviolet-visible spectroscopy (UV-vis). The strategy of fractionating the PS, sequentially, with organic solvents of increasing polarity is a reliable analytical procedure for humic substance sample separation because it results in more purified fractions. FTIR, 1 H NMR and 13 C NMR results showed that hexane extract consisted mainly of aliphatic hydrocarbon structures. Their contents in the extracts decreased as the polarity of the extracting solvent increased and the content of oxygen functional groups increased. Carboxylic and carboxylate functional groups were found in the acetone extract, and ester and ether functions were predominantly found in the ethanol extract. EPR spectra revealed some Fe 3+ complexes with rhombic structure (g 1 = 4.3; g 2 = 9.0) in the humic fractions and in all solvent extracts, except hexane. Quasi-octahedral Fe 3+ complexes (g = 2.3; ΔH pp ≤400 G) were found in the HU fraction and in the acetone extract. The organic free radical content in the HA fraction was higher than the non-fractionated PS sample and HU fraction.

In this letter we present a new 2,4,4-trimethyl-2-oxazoline anion-zinc derivative that has a remarkable thermal stability when compared with the corresponding cyanocuprate counterpart. The yields from conjugated addition to several 2-nitrovinyl benzenes are moderate to good and the reaction itself is easier to execute and cleaner. As an application, this methodology was applied to an alternative synthesis of (±)-Rolipram, a drug with several interesting biological activities.

Dimers of 4-substituted 2-methoxy phenols were prepared using methyltributylammonium permanganate (MTBAP) in dichloromethane. This methodology allows the selective coupling of such compounds preserving other moieties easily oxidized by permanganate anion in aqueous solution.

Synthesis of a model compound 4 structurally related to a bioactive lactone 3 isolated from Otoba parvifolia has been accomplished. The good match between the NMR data of both compounds suggests they have identical bicyclic [3.3.1] carbon skeletons.

The oxazoline cyanocuprates addition to conjugated cyanoalkenes, was shown to be an efficient method for the synthesis of a variety of γ-cyanooxazolines, interesting intermediates with different, but convertible, functions in a symmetrical position.

A simple methodology for the determination of the fatty acid composition of edible oils through (1)H NMR is proposed. The method is based on the fact that all fatty acid chains are esterified to a common moiety, glycerol, and the quantification is done directly in the (1)H NMR spectra through the relationship between the areas of a characteristic signal of each fatty acid and a signal of the glycerol moiety, without the use of mathematical equations. The methodology was successfully applied to determine the fatty acid composition of several edible oils, with equivalent results to those given by the AOAC Official method by gas chromatography. Its main advantages are simplicity and the lack of need for sample pre-treatment such as derivatization or extraction.

Current studies of oxazoline cyanocuprates addition to conjugated nitroalkenes, and their improved reactivity when compared to lithium oxazoline anions, has shown to be an efficient method for the synthesis of a variety of γ-nitrooxazolines, an interesting intermediate of γ-amino acids.

As part of our ongoing investigation on the versatility of 4,4-dimethyl-2-oxazoline derivatives, we present a straightforward synthesis of chiral lactone pheromones from readily available starting materials. As an application, we describe the diastereoselective synthesis of cis and trans-2-methyl-5-hexanolide (1), a pheromone component of the carpenter bee Xylocopa hirutissima, and a formal synthesis of (4R,5Z)-5-tetradecen-4-olide (2), the sex pheromone of the Japanese beetle Popillia japonica.

This paper describes the preparation of a series of oxazoline cuprates by reaction of an oxazoline lithium anion with copper(I) salts: CuBr.DMS, Cul and CuCN in THF solution. The oxazoline cyanocuprate showed the best reactivity using enones as electrophiles.

Introduction of a synthon equivalent to a carboxymethyl anion to enones and nitroalkenes, through a 1,4-addition reaction of 2,4,4-trimethyl-2-oxazoline cyanocuprate 3, proved to be an interesting methodology for the synthesis of natural products such as (±)-methyl jasmonate (1) and (±)-baclofen (2). A introdução de um grupamento equivalente ao ânion carboximetil a enonas e nitroalquenos através da reação de adição 1,4 do cianocuprato da 2,4,4-trimetil-2-oxazolina 3, resulta numa metodologia interessante para a síntese de produtos naturais como (±)-metil jasmonato (1) e (±)-baclofen (2).

As an extension to our work on intramolecular annulations via silyloxycyclopropane derived anions, we have investigated the chemistry of cyclopentyl cyclopropane systems, 6-9, in an effort to prepare stereospecifically functionalized hydrindenones. The intramolecular closures of the cyclopropane-derived anions were less stereoselective and more complicated than the corresponding cyclohexyl systems. Nevertheless, modest yields of isomeric hydrinenones such as 20 and 21 were obtained as well as several products derived from a prototropic shift to form the cyclopentanone enolates. These latter products possessed the 5,5-pentalenone systems, 22 and 23. Como uma extensão de nosso trabalho em anelações intramoleculares via anions derivados de sililoxiciclopropanos, investigamos a química dos sistemas ciclopentilciclopropanos 6-9, em um esforco visando a preparação de hidrindenonas estereoespecificamente funcionalizadas. As ciclizações intramoleculares de anions derivados do ciclopropano foram menos estereosseletivas e mais complicadas do que aquelas com o corresponente sitema cicloexila. Entretanto, rendimentos modestos de hidrindenonas, tais como 20 e 21, foram obtidos, assim como vários produtos derivados a partir de um deslocamento prototrópico que gerou enolatos de ciclopentanona. Estes últimos produtos possuem os sistemas 5,5-pentalenônicos 22 e 23.