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1.
Food Res Int ; 187: 114398, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38763656

RESUMEN

Nowadays, it is important to monitor the freshness of meat during storage to protect consumers' health. Volatile organic compounds (VOCs) are responsible for odour and taste of food, and they give an indication about meat quality and freshness. This study had the aim to seek and select potential new markers of meat spoilage through a semi-quantitative analysis in five types of meat (beef, raw and baked ham, pork sausage and chicken) and then to develop a new quantitative analytical method to detect and quantify potential markers on five types of meat simultaneously. Firstly, a new headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) method was developed to evaluate the volatile profile of five types of meat, preserved at 4 °C for 5 days. Among the 40 compounds identified, 15 were chosen and selected as potential shelf-life markers on the basis of their presence in most of meat samples or/and for their constant increasing/decreasing trend within the sample. Afterwards, a quantitative HS-SPME-GC-MS analytical method was developed to confirm which VOCs can be considered markers of shelf-life for these meat products, stored at 4 °C for 12 days. Some of the compounds analyzed attracted attention as they can be considered markers of shelf-life for at least 4 types of meat: 1-butanol, 3-methylbutanol, 1-hexanol, 2-nonanone, nonanal, 1-octen-3-ol and linalool. In conclusion, in this study a new quantitative HS-SPME-GC-MS analytical method to quantity 15 VOCs in five types of meat was developed and it was demonstrated that some of the compounds quantified can be considered markers of shelf-life for some of the meat products analyzed.


Asunto(s)
Almacenamiento de Alimentos , Cromatografía de Gases y Espectrometría de Masas , Productos de la Carne , Microextracción en Fase Sólida , Compuestos Orgánicos Volátiles , Compuestos Orgánicos Volátiles/análisis , Cromatografía de Gases y Espectrometría de Masas/métodos , Microextracción en Fase Sólida/métodos , Productos de la Carne/análisis , Animales , Porcinos , Odorantes/análisis , Bovinos , Aldehídos/análisis , Pollos , Cetonas/análisis , Pentanoles/análisis , Monoterpenos Acíclicos/análisis , Octanoles
2.
Biomedicines ; 11(9)2023 Sep 08.
Artículo en Inglés | MEDLINE | ID: mdl-37760935

RESUMEN

Alopecia is a pathological and multifactorial condition characterised by an altered hair growth cycle and ascribed to different pathogenic causes. Cell energetic imbalances in hair follicles occurring in this disorder could lead to the production of some "metabolic wastes", including squalene and lactic acid, which could be involved in the clinically observed sheath damage. The aim of this work was the extraction and analytical quantification of squalene and lactic acid from hair bulbs of subjects with clinical alopecia in comparison with controls, using HPLC-DAD and HPLC-MS techniques. The analytical quantification was performed after a preliminary observation through a polarised optical microscope to assess sheath damage and morphological alterations in the cases group. A significantly larger amount of squalene was quantified only in subjects affected by alopecia (n = 31) and with evident damage to hair sheaths. For lactic acid, no statistically significant differences were found between cases (n = 21) and controls (n = 21) under the experimental conditions used. Therefore, the obtained results suggest that squalene can represent a metabolic and a pathogenic marker for some alopecia conditions.

3.
Molecules ; 28(3)2023 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-36770714

RESUMEN

The aim of this research was to develop innovative cheeses fortified with vitamin D3 (VD3). Formulation studies and analyses of textural properties and chemicals were carried out for these developments. Two traditional Italian varieties of cheese (giuncata and burrata) were studied. For giuncata, the fortification of milk for cheese production provided a VD3 retention level of 43.9 ± 0.6% in the food matrix. For burrata, the VD3 ingredient was incorporated into the creamy inner part after mixing, maintaining the textural quality of the product (adhesiveness 4.3 ± 0.4 J × 10-3; firmness 0.7 ± 0.0 N; and cohesiveness 0.8 ± 0.2). The optimized enrichment designs allowed to obtain homogenous contents of VD3 during the production of giuncata (0.48 ± 0.01 µg/g) and burrata cheeses (0.32 ± 0.02 µg/g). Moreover, analyses revealed the high stability of VD3 during the storage of the two fortified cheese types (2 weeks, 4 °C). These fortification designs could be implemented at an industrial scale to obtain new cheese types enriched in VD3 and thus contribute to the reduction in VD deficiency prevalence.


Asunto(s)
Queso , Vitamina D , Animales , Vitamina D/análisis , Queso/análisis , Alimentos Fortificados/análisis , Manipulación de Alimentos , Vitaminas/análisis , Leche/química , Italia
4.
Foods ; 11(19)2022 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-36230109

RESUMEN

Green coffee (Coffee arabica and Coffee robusta) is one of the most commonly traded goods globally. Their beans are enriched with polyphenols and numerous health benefits are associated with their consumption. The main aim of this work was to develop a new and fast analytical HPLC-MS/MS method to simultaneously determine six flavonoid polyphenolic compounds (quercetin, rutin, isorhamnetin, quercetin-3-glucouronide, hyperoside, and quercitrin) in 22 green coffee samples from six different geographical origins (Ethiopia, Brazil, Guatemala, Nicaragua, India and Colombia). In addition, by adjusting pH, temperature, solvent type, and extraction duration, several extraction methods such as acidic and alkaline hydrolysis, and extraction without hydrolysis were evaluated. The optimal extraction procedure in terms of recovery percentages (78.67-94.09%)was acidic hydrolysis at pH 2, extraction temperature of 60 °C, extraction solvent of 70% ethanol, and extraction duration of 1.5 h. Hyperoside (878-75 µg/kg) was the most abundant compound followed by quercitrin (408-38 µg/kg), quercetin (300-36 µg/kg), rutin (238-21 µg/kg), and quercetin-3-glucouronide (225-7 µg/kg), while isorhamnetin (34-3 µg/kg) showed the lowest amount. Overall, green coffee beans are rich in flavonoid polyphenolic compounds and could be used as part of a healthy diet.

5.
Antioxidants (Basel) ; 11(2)2022 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-35204077

RESUMEN

New hydrophobic derivatives of cinnamic and hydroxycinnamic (ferulic and cumaric) acids obtained by chemical esterification of the carboxylic group with C10 linear alcohol were studied to evaluate their antioxidant capacity toward the superoxide anion and hydrogen peroxide in physiological buffer and in extra-virgin olive oil (EVO) or Nigella sativa oils. Results showed that cumaric and ferulic acids have higher antioxidants activity against superoxide anion and hydrogen peroxide than the other compounds. Cumaric acid and its C10-ester derivative were selected to be incorporated into EVO or Nigella sativa oil-based emulsions. The prepared emulsions had a comparable particle size distribution (in the range of 3-4 µm) and physical stability at least up to three months. Nigella sativa oil-based emulsions loaded with cumaric acid or its C10-ester showed a higher capacity to scavenger superoxide anion and hydrogen peroxide than EVO oil-based emulsions. In conclusion, cumaric acid or its C10-ester could promote the antioxidant properties of Nigella sativa oil when formulated as emulsions.

6.
Molecules ; 26(24)2021 Dec 20.
Artículo en Inglés | MEDLINE | ID: mdl-34946772

RESUMEN

Plasma activated water (PAW) has proven to be a promising alternative for the decontamination of rocket leaves. The impact of PAW on the volatile profile, phytosterols, and pigment content of rocket leaves was studied. Leaves were treated by PAW at different times (2, 5, 10, and 20 min). Compounds of the headspace were detected and quantified using GC-MS analysis. A total of 52 volatile organic compounds of different chemical classes were identified. Glucosinolate hydrolysis products are the major chemical class. PAW application induced some chemical modifications in the volatile compounds. Changes in the content of the major compounds varied with the increase or decrease in the treatment time. However, PAW-10 and -2 were grouped closely to the control. A significant decrease in the content of ß-sitosterol and campesterol was observed after PAW treatment, except for PAW-10, which showed a non-significant reduction in both compounds. A significant increase in ß carotene, luteolin, and chlorophyll b was observed after the shortest treatment time of PAW-2. A reduction in chlorophyll content was also observed, which is significant only at longer treatment, or PAW-20. Overall, PAW has proven to be a safe alternative for rocket decontamination.


Asunto(s)
Brassicaceae/química , Hojas de la Planta/química , Gases em Plasma/química , Compuestos Orgánicos Volátiles/química , Agua/química
7.
Molecules ; 26(13)2021 Jun 24.
Artículo en Inglés | MEDLINE | ID: mdl-34202706

RESUMEN

Espresso coffee (EC) is a common coffee preparation technique that nowadays is broadly widespread all over the globe. Its popularity is in part attributed to the intense aroma and pleasant flavor. Many researchers have studied and reviewed the aroma of the coffee, but there is a lack of specific review focused on EC aroma profile even if it is intensively investigated. Thus, the objective of the current review was to summarize the aroma profile of EC and how different preparation variables can affect EC flavor. Moreover, a collection of diverse analytical procedures for volatile analysis was also reported. The findings of this survey showed that the volatile fraction of EC is extremely complex, but just some compounds are responsible for the characteristic aroma of the coffee, such as some aldehyde, ketones, furanones, furans, sulfur compounds, pyrazines, etc. In addition, during preparation, some variables, e.g., temperature and pressure of water, granulometry of the coffee particle, and brew ratio, can also modify the aroma profile of this beverage, and therefore its quality. A better understanding of the aroma fraction of EC and how the preparation variables should be adjusted according to desired EC would assist coffee workers in obtaining a higher quality product.


Asunto(s)
Café/química , Calor , Odorantes/análisis , Compuestos Orgánicos Volátiles/análisis
8.
Molecules ; 25(24)2020 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-33334053

RESUMEN

Truffles are underground edible fungi that grow symbiotically with plant roots. They have been globally considered as one of the most expensive foods because of their rarity, unique aroma, and high nutritional value as antioxidant, anti-inflammatory, antiviral, hepatoprotective, anti-mutagenic, antituberculoid immunomodulatory, antitumor, antimicrobial, and aphrodisiac. The unique flavor and fragrance of truffles is one of the main reasons to get worldwide attraction as a food product. So, the aim of this review was to summarize the relevant literature with particular attention to the active aroma components as well as the various sample preparation and analytical techniques used to identify them. The major analytical methods used for the determination of volatile organic compounds (VOC) in truffles are gas chromatography (GC), proton-transfer-reaction mass spectrometry (PTR-MS), and electronic nose sensing (EN). In addition, factors influencing truffle aroma are also highlighted. For this reason, this review can be considered a good reference for research concerning aroma profiles of different species of truffles to deepen the knowledge about a complex odor of various truffles.


Asunto(s)
Ascomicetos/química , Odorantes/análisis , Compuestos Orgánicos Volátiles/análisis , Técnicas de Química Analítica , Compuestos Orgánicos Volátiles/química
9.
J Mass Spectrom ; 55(11): e4519, 2020 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-32368836

RESUMEN

Spent coffee ground (SCG) is the remaining residue produced after extraction of coffee, and it is considered a source of unextracted bioactive compounds. For this, in the latest years, the attention has been focused to innovative reuses that can exploit the potentiality of SCG. Unfortunately, the content of bioactive compounds has not been thoroughly studied yet, and the major of publication has investigated the caffeine and chlorogenic acids levels, total polyphenol contents, and total flavonoid content. Hence, these approaches have determined only an estimation of flavonoids and polyphenols content and lack on single polyphenols investigation. Therefore, the objective of the current work was to provide a deep characterization of bioactive compounds in SCG. For this purpose, a new analytical method for the quantification of 30 molecules, including caffeine, chlorogenic acids, phenolic acids, flavonoids, and secoiridoids, has been developed using high-performance liquid chromatography tandem mass spectrometry. Moreover, several extraction procedures, that is, liquid-solid extraction assisted and not by ultrasounds, testing diverse solvents, were evaluated. Liquid-solid extraction assisted by sonication, with water/ethanol (30/70, v/v), resulted the best in terms of total bioactive compounds, and, once validated, the new analytical method was applied to five different espresso SCG samples. Data showed that caffeine (means: 1193.886 ± 57.307 mg kg-1 ) and chlorogenic acids (means of total CQAs: 1705.656 ± 88.694 mg kg-1 ) were the most abundant compounds in all SCG samples followed by phenolic acids such as caffeic, ferulic, gallic, p-coumaric, syringic, trans-cinnamic, and vanillic acid. Moreover, some flavonoids, that is, rutin, cyanidin 3-glucoside, and quercetin, occurred in almost all samples. This work provided a deepened characterization of bioactive compounds in SCG and can contribute to develop new strategies of reuses.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Café/química , Espectrometría de Masas en Tándem/métodos , Cafeína/análisis , Ácido Clorogénico/análisis , Coffea/química , Flavonoides/análisis , Iridoides/análisis , Fenoles/análisis , Polifenoles/análisis
10.
Food Res Int ; 133: 109220, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32466917

RESUMEN

Espresso coffee (EC) is a complex and much appreciated beverage among coffee consumers. The extraction phase of EC, a combination of physical and chemical variables in a very short time, has a direct effect on the flavour of the beverage. This research aims to optimize the extraction process of EC by decreasing the amount of ground coffee from 14 g to 12 g (double cup), while keeping constant the particle size of ground coffee and the physical parameters of the espresso machine, making use of the following accessories: two different filter baskets, and four different heights of perforated discs (4-7 mm). Quantitative analyses on several organic acids (acetic, citric, caffeic, malic, tartaric) and caffeine, trigonelline, nicotinic and 5-caffeoylquinic acid are carried out with HPLC-VWD through a newly developed method. This combines the quantification of organic acids, obtained through HPLC-VWD, with the results of a sensory panel evaluation on the descriptive notes of EC. The outcomes will trigger and support further studies on different extraction processes, to develop more sustainable and economically affordable coffee of high quality.


Asunto(s)
Coffea , Café , Cafeína/análisis , Cromatografía Líquida de Alta Presión , Extractos Vegetales
11.
Food Res Int ; 121: 730-737, 2019 07.
Artículo en Inglés | MEDLINE | ID: mdl-31108803

RESUMEN

The present study sought to develop a headspace solid-phase microextraction (HS-SPME) gas chromatography-mass spectrometry (GC-MS) method to quantify free fatty acids (FFAs) and hexanal in cheese, and to track theirs levels over time. The developed method was applied on Fresh Asiago and Grana Padano cheeses, and FFAs and hexanal levels were monitored over 4 and 12 weeks respectively. Their evolutions were also compared from two types of packaging films: a high-density polyethylene (HDPE) package and a packaging bag named Ideabrill®. The later allowed a lower increase of these analytes (11.6-fold increase for Grana Padano and 5.9 for Fresh Asiago) compared to the HDPE packaging (21.5-fold increase for Grana Padano and 7.4 for Fresh Asiago). This method can contribute to the optimization of analytical methods in food industry for studies on shelf life, quality control or food packaging.


Asunto(s)
Aldehídos/análisis , Queso/análisis , Ácidos Grasos no Esterificados/análisis , Almacenamiento de Alimentos , Cromatografía de Gases y Espectrometría de Masas , Microextracción en Fase Sólida , Análisis de los Alimentos , Embalaje de Alimentos , Compuestos Orgánicos Volátiles/análisis
12.
J Mass Spectrom ; 53(9): 842-848, 2018 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-29925121

RESUMEN

Lignans are polyphenolic compounds that are considered phytoestrogens for their plant origins, and they possess different biological activities. Three different extraction methods, ie, "dilute and shoot", acidic hydrolysis, and enzymatic digestion, have been compared for extracting lignans (secoisolariciresinol (SECO), matairesinol (MAT), and lariciresinol (LARI)) from espresso coffee (EC) by using high-performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS). The best recovery values (SECO: 97%, LARI: 98%, and MAT: 93%) were obtained by using enzymatic hydrolysis with Clara-Diastase at 10% (w/v), keeping the sample at 37°C for 3 hours. For this reason, this method has been chosen and then applied to quantify lignans in 9 different EC samples from 5 different geographical origins (Brazil, Colombia, El Salvador, Ethiopia, and India). Secoisolariciresinol and LARI were found in all EC samples from 27.9 to 52.0 µg L-1 and from 5.3 to 27.8 µg L-1 respectively, contrary to MAT that it was not possible to detect it in each type of coffee. This method confirms the high specificity and sensitivity of MS/MS system for detecting bioactives in complex matrix such as coffee.

13.
Int J Food Sci Nutr ; 69(5): 557-565, 2018 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-29117733

RESUMEN

Consumption of legumes has become popular among health-conscious consumers due to the high levels of nutrients such as proteins, dietary fibres, minerals, vitamins and micronutrients like polyphenols. Ten legumes cultivars organically and conventionally grown were compared regarding their chemical profiles in terms of total phenolic content (TPC), total anthocyanin content (TAC), total flavonoid content (TFC) and their antioxidant capacity. The chemical profiles (i.e. free phenolics and anthocyanins) were determined with aid of new high-performance liquid chromatography-diode array detection (HPLC-DAD) method able to identify two individual anthocyanins and 15 polyphenols. Results showed that phenolic acids, namely gallic acid, caffeic acid, syringic acid and ferulic acid, are mainly significantly higher in the organic samples with respect to the conventional ones. All organic legumes showed a higher antioxidant capacity with respect to conventional samples with the exception of red and yellow dehulled lentils.


Asunto(s)
Antioxidantes/química , Cromatografía Liquida/métodos , Fabaceae/química , Polifenoles/química , Antocianinas/química , Compuestos de Bifenilo , Flavonoides/química , Picratos , Reproducibilidad de los Resultados
14.
J Mass Spectrom ; 51(9): 698-703, 2016 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-27628757

RESUMEN

A new method for extracting isoflavones from espresso coffee (EC) was coupled with high-performance liquid chromatography-tandem mass spectrometry (MS/MS) for the first time to analyse five isoflavones, which included both a glycosilated form, genistin and the aglycons daidzein, genistein, formononetin and biochanin A. Isoflavones were extracted from coffee samples using methanol, stored in a freezer overnight to precipitate proteic or lipidic residues and purified on SPE C18 cartridges before high-performance liquid chromatography-MS/MS analysis. The recovery percentages obtained by spiking the matrix at concentrations of 10 and 100 µg l(-1) with a standard mixture of isoflavones were in the range of 70 to 104%. The limits of detection and limits of quantification were in the range of 0.015-0.3 µg l(-1) and 0.05-1 µg l(-1) , respectively. Once validated, the method was used to analyze the concentrations of isoflavones in six ECs and ten ground coffee samples. Only formononetin and biochanin A were found, and their respective concentrations ranged from 0.36 to 0.41 µg l(-1) and from 0.58 to 3.26 µg l(-1) in ECs and from 0.36 to 4.27 µg kg(-1) and from 0.71 to 3.95 µg kg(-1) in ground coffees. This method confirms the high specificity and selectivity of MS/MS systems for detecting bioactives in complex matrices such as coffee.Copyright © 2016 John Wiley & Sons, Ltd.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Café/química , Isoflavonas/análisis , Extracción en Fase Sólida/métodos , Espectrometría de Masas en Tándem/métodos , Límite de Detección , Modelos Lineales , Reproducibilidad de los Resultados
15.
Food Chem ; 174: 487-94, 2015 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-25529710

RESUMEN

Legumes are an excellent source of macronutrients and phytochemicals as isoflavones. The aim of this work was to develop a new analytical method for determining five isoflavone compounds, three of which are aglycons, namely daidzein, genistein, biochanin A, and two of which, daidzin and genistin, are glycosilated, in lentils and other pulses, using an effective clean-up system and UHPLC-MS/MS (triple quadrupole) method. The recoveries obtained by spiking the lentil samples with a standard mixture of isoflavones at three levels of fortification (5, 25 and 100 µg kg(-1)) were in the range of 54.4-111.1%, 68.6-91.1%, and 84.4-114%, respectively. The method was applied to analyse 48 lentil samples from central Italy and pulses for determining the isoflavone content, which was found to range from 1.1 to 95.6 µg kg(-1).


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Fabaceae/química , Isoflavonas/análisis , Espectrometría de Masas en Tándem/métodos , Análisis de los Alimentos/métodos , Congelación , Isoflavonas/química , Fitoestrógenos/análisis , Fitoestrógenos/química
16.
J Agric Food Chem ; 61(8): 1702-9, 2013 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-23305351

RESUMEN

Legumes contain a rich variety of phytochemicals as soyasaponins, triterpenoidal glycosides that possess multiple health-promoting properties, such as lowering of cholesterol. In this work, the quantification of soyasaponins I and ßg in 60 raw and cooked legumes by using a solid phase extraction (SPE) coupled to a liquid chromatography (LC)-mass spectrometry (MS) method was carried out. Results showed that lentils are a good source of soyasaponins, with a content of soyasaponin I that ranged from 636 to 735 mg kg(-1) and of soyasaponin ßg from 672 to 1807 mg kg(-1). The cooking process produced a small loss of soyasaponins in water, that is, 4.8-8.7%, and partially converted soyasaponin ßg into soyasaponin I. In addition, the bioaccessibility of soyasaponins I in lentils was studied; the values ranged from 8.9 ± 0.3 to 10.6 ± 1.1% in the duodenal compartment. On the basis of these results, soyasaponins could be effective in lowering exogenous cholesterol.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Digestión , Fabaceae/química , Fabaceae/metabolismo , Espectrometría de Masas/métodos , Ácido Oleanólico/análogos & derivados , Saponinas/análisis , Extracción en Fase Sólida/métodos , Disponibilidad Biológica , Humanos , Ácido Oleanólico/análisis , Ácido Oleanólico/aislamiento & purificación , Ácido Oleanólico/metabolismo , Saponinas/aislamiento & purificación , Saponinas/metabolismo
17.
Food Chem ; 132(3): 1592-1599, 2012 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-29243654

RESUMEN

Montepulciano is one of the most famous and important red-berried grapes of Italy. This article presents and discusses a comparative study of aroma profile and phenolic content of the Montepulciano wine from the Marches and the Abruzzo regions. The volatile composition of wines was determined by using headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The PDMS fibre was chosen. The dominating esters in Montepulciano wines were ethyl hexanoate, ethyl decanoate, and ethyl octanoate, whereas phenyl ethanol and 3-methyl-1-butanol were dominating alcohols. Phenolic compounds, namely gallic acid, p-coumaric acid, trans-ferulic acid, caffeic acid, trans-resveratrol, (+)-catechin and (-)-epicatechin, were examined using HPLC-MS with direct injection of wine samples. The total phenolic content of the analysed wines was in the range of 30.4-61.9mgl-1. The presence of high amounts of esters seems to characterise the volatiles of Montepulciano wines from the Marches, whereas a high level of alcohols was found in Montepulciano wines from Abruzzo. Moreover, multivariate chemometric techniques, such as cluster analysis and principal component analysis, supported this thesis. Headspace solid phase microextraction and gas chromatography-mass spectrometry were used to analyse 20 commercial wine samples (Montepulciano monovarietal red wines) from the Marches (10 samples) and Abruzzo (10 samples).

18.
Org Lett ; 8(18): 4093-6, 2006 Aug 31.
Artículo en Inglés | MEDLINE | ID: mdl-16928082

RESUMEN

Friedel-Crafts reaction of indoles with alpha-amido sulfones in the presence of montmorillonite K-10 leads unexpectedly to 3-(1-arylsulfonylalkyl) indoles in good yield. The obtained products can be further desulfonylated under reductive or alkylative conditions giving linear and branched 3-substituted indoles.


Asunto(s)
Silicatos de Aluminio/química , Indoles/química , Sulfonas/química , Catálisis , Arcilla , Estructura Molecular
19.
J Org Chem ; 70(5): 1941-4, 2005 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-15730329

RESUMEN

The combination of cerium(III) chloride heptahydrate and sodium iodide supported on silica gel is known to promote Michael-type additions. Continuing our work on solvent-free conditions, the CeCl3.7H2O-NaI-SiO2 system catalyzes the addition of a variety of indoles and nitroalkenes, giving 2-indolyl-1-nitroalkane derivatives in good yields. Development of this method has resulted in a new protocol for the synthesis of 4-substituted beta-carbolines.


Asunto(s)
Alcanos/síntesis química , Alquenos/química , Carbolinas/síntesis química , Ácidos Carboxílicos/síntesis química , Nitrocompuestos/síntesis química , Estructura Molecular
20.
J Org Chem ; 70(1): 169-74, 2005 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-15624919

RESUMEN

Conjugate addition of heteroatom nucleophiles to carbon-carbon double bonds conjugated with a strong electron-withdrawing group is one of the most important new bond-forming strategies in synthetic organic chemistry. Among the methods for these Michael additions, Lewis acids have shown the best promoter activity, and in particular, the use of reagents impregnated over inorganic supports is rapidly increased. With the increase of environmental consciousness in chemical research, the solvent-free Michael addition has attracted our attention. In continuation of our ongoing program to develop synthetic protocols utilizing cerium trichloride, we report an extension of the CeCl(3).7H(2)O/NaI combination supported under solvent-free conditions to promote heteroatom Michael addition. Using neutral alumina (Al(2)O(3)) as solid support permits us to circumvent some of the problems associated with the procedure where the inorganic support is silica gel. The CeCl(3).7H(2)O/NaI/Al(2)O(3) system works well for hetero-Michael additions utilizing weakly nucleophiles such as imidazoles and carbamates, and also the reaction proceeds with good yields in the case of Michael acceptors different from alpha,beta-unsaturated carbonyl compounds. An important synthetic application of this our methodology is the intramolecular aza-Michael reaction in producing 4-piperidinone derivatives, which are of interest as synthetic intermediates toward important classes of heterocycles.

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