TiCl4/Et3N‑Mediated Condensation of Acetate and Formate Esters: Direct Access to β‑Alkoxy- and β‑Aryloxyacrylates

A methodology to build (E)-β-alkoxy- and (E)-β- aryloxyacrylate moieties from acetate and formate esters promoted by the TiCl4/Et3N system is presented. The reaction is compatible with a broad range of structural skeletons and elapses through an unusual condensation pathway. Taking into account the obtained results, we propose a plausible mechanism involving a bimetallic titanium intermediate for this type of transformation

Multivariate optimization of the KharascheSosnovsky allylic oxidation of olefins

The multivariate optimization method known as simplex is applied to the KharascheSosnovsky allylic oxidation of double bonds. By applying this method, the amounts of three variables (copper source, oxidant, and additive) are optimized at the same time. Under the conditions thus obtained the reaction takes place in a considerable shorter time, being the alkene the limiting reagent. These conditions are applied to some monoterpenes and sesquiterpenes leading regioselectively to the corresponding benzoate esters, opening a route to the employment of this reaction in the synthesis of more complex molecules

Optimization by Response Surface Methodology (RSM) of the Kharasch−Sosnovsky Oxidation of Valencene

Response surface methodology (RSM) has been employed to model and optimize the Kharasch−Sosnovsky allylic oxidation of valencene. The detailed effects of the amounts of oxidant, substrate, copper catalyst, 1,8- diazabicyclo[5.4.0]undec-7-ene (DBU), and temperature have been studied. The concentration of substrate and quantity of oxidant have been determined as the most significant variables. The interaction effects on the yield have been investigated using a three-level full-factorial design. The yield of benzoyloxyvalencene has been improved to 99%. Analysis of variance (ANOVA) has been used to evaluate the goodness of fit of the model

Acyloxylation of 1,4-Dioxanes and 1,4-Dithianes Catalyzed by a Copper−Iron Mixed Oxide

The use of a copper−iron mixed oxide as a heterogeneous catalyst for the efficient synthesis of α-acyloxy-1,4-dioxanes and 1,4-dithianes employing t-butyl peroxyesters is reported. The preparation and characterization of the catalyst are described. The effect of the heteroatoms and a plausible mechanism are discussed. The method is operationally simple and involves low-cost starting materials affording products in good to excellent yields

DoE (Design of Experiments) Assisted Allylic Hydroxylation of Enones Catalysed by a Copper–Aluminium Mixed Oxide

The allylic hydroxylation of enones using dioxygen as the oxidant has been studied. The reaction was first examined in the absence of any catalyst, using β-ionone as a model substrate. Then a new copper–aluminium mixed oxide, Cu–Al Ox, was prepared and characterized in order to be used as a catalyst. This oxide showed good activity, and provided the corresponding γ- or ε-hydroxylated enones, starting from different α,β- or α,β,γ,δ-unsaturated ketones. In all cases, the yields were significantly improved compared to experiments run in the absence of the catalyst. The reaction was selective, and the formation of epoxides or other overoxidation products was detected only to a minor extent. The described procedure is a technically straightforward synthetic alternative to those methods described to date involving many reaction steps or toxic reagents. The reactions were optimized using design of experiments techniques (DoE)

Anales de Edafología y Agrobiología Tomo 41 Número 1-2

Suelos. Mineralización del carbono y del nitrógeno en suelos forestales de Galicia, por R. M. de Anta y F. Díaz-Fierros.-- Características bioclimáticas de interés edafológico de las Sierras de Orce y María, por L J. Alias y J. Martínez Sánchez.-- Factores formadores de los suelos de la cuenca del río Dilar (Sierra Nevada), por R. Delgado Calvo-Flores, E. Barahona y J. Linares.-- Distribución de los suelos de la cuenca alta del río Dilar (Sierra Nevada), por R. Delgado Calvo-Flores, E. Barahona y J. Linares.-- Los mollisoles de la cuenca alta del río Dilar (Sierra Nevada), por R. Delgado Calvo-Flores, E. Barahona, F. Huertas y J. Linares.-- Los inceptisoles de la cuenca alta del río Dilar (Sierra Nevada), por R. Delgado CalvoFlores, E. Barahona, F. Huertas y J. Linares.-- Los entisoles de la cuenca alta del río Dilar (Sierra Nevada), por R. Delgado Calvo-Flores, E. Barahona, F. Huertas y J. Linares.-- Aspectos edafogeoquímicos de la salinidad en la submeseta Sur (Toledo). l. Estudio hidrogeoquímico, por J. Gumuzzio Fernández, J. Astudillo Pastor y J. Batlle Sales.-- Modelo experimental de alteración de oligisto. Aplicación al estudio óptico de minerales opacos, por Hoyos de Castro, A., Remando Costa, J., Remando Massanet, l. y Millán Pérez, R.-- Modelo experimental de alteración de feldespatos. Aplicación de tinción. l. Ortosa. por Hoyos de Castro, A., Hernando Massanet, l. Remando Costa, J. y Yunta, M. V..-- Modelo experimental de alteración de feldespatos. Aplicación al método de tinción. II Labradorita, por Hoyos de Castro, A. Hernando Massanet, I., Hernando Costa, J. y Pisonero Ruiz, L.-- Taxonomía númerica. Su aplicación a la clasificación de los suelos rojos españoles, por L. Alcalá del Olmo, B. y F. Monturiol Rodríguez.-- Propiedades químicas de suelos y niveles de nutrientes inorgánicos en aciculas de A. Pinsapo de Grazalema (Cádiz España), por Paneque, G. y Corral, L.-- Morfología y propiedades químicas de suelos forestales de Granlema (Cádi7., España). l. Suelos bajo Quercus rotundifoliae y Quercus fagineae, por, C. Benírez, J. Mérida, L. Corral y G. Paneque.-- Morfología y propiedades químicas de suelos forestales de Grazalema (Cádiz, España). II. Suelos bajos Quercus suber y A bies pinsapo, por C. Benírez, J. Mérida, L. Corral y G. Paneque.-- Morfología y propiedades químicas de suelos forestales de Grazalema (Cádiz,España). III. Tipovergencia del perfil húmico, por J. Mérida, L. Corral y G. Paneque.-- Fertilidad de Suelos. Q/1 ratio saline soils belongig to Ebro Valley (Spain), por Benigna Elizalde and M. Fernández.-- Fertilidad química de los suelos del valle del río Guadalhorce (Málaga), por S. Bruque, M. Martínez Lara y L. Moreno Real.-- Absorción de K por ryegrass y Trifolium en suelos deficientes, por J. A. Diez.— Nutrición y Fisiología Vegetal. Correlaciones entre bioelementos: Estudio realizado en Trifo/ium subrerraneo L. y A vena saliva L., por Gómez Gutiérrez, J. M. y Hoyos Alonso, C. de.-- Influencia del ácido húmico sobre la nutrición mineral y el desarrollo radicular de plantas de maíz cultivadas en soluciones nutritivas normales y carentes de Fe y Mn, por Fortún, C. y López-Fando, C.-- Notas.-- BibliografíaPeer reviewe