The Heck reaction of allylic alcohols catalysed by an N-heterocyclic carbene-Pd(ii) complex and toxicity of the ligand precursor for the marine benthic copepod Amphiascoides atopus.

The palladium-catalysed reaction of aryl halides and allylic alcohols is an attractive method for obtaining α,ß-unsaturated aldehydes and ketones, which represent key intermediates in organic synthesis. In this context, a 1,2,3-triazol-5-ylidene (aNHC)-based palladium(ii) complex formed in situ has been found to be a selective catalyst for the syntheses of building blocks from the corresponding aryl halides and allylic alcohols, with yields ranging from 50% to 90%. The lack of toxic effects of the ligand precursor (1,2,3-triazolium salt) of the palladium(ii) complex for the harpacticoid copepod Amphiascoides atopus allowed us to contrast the efficiency of the catalytic system with the potential impact of the principal waste chemical in global aquatic ecosystems, which has not been previously addressed.

Synthesis of cycloveratrylene macrocycles and benzyl oligomers catalysed by bentonite under microwave/infrared and solvent-free conditions.

Tonsil Actisil FF, which is a commercial bentonitic clay, promotes the formation of cycloveratrylene macrocycles and benzyl oligomers from the corresponding benzyl alcohols in good yields under microwave heating and infrared irradiation in the absence of solvent in both cases. The catalytic reaction is sensitive to the type of substituent on the aromatic ring. Thus, when benzyl alcohol was substituted with a methylenedioxy, two methoxy or three methoxy groups, a cyclooligomerisation process was induced. Unsubstituted, methyl and methoxy benzyl alcohols yielded linear oligomers. In addition, computational chemistry calculations were performed to establish a validated mechanistic pathway to explain the growth of the obtained linear oligomers.

Three new diarylbutane lignans from the resin of Bursera fagaroides.

Three new diarylbutane lignans, named 9-acetyl-9'-pentadecanoil-dihydroclusin (1), 2,3-demethoxy-secoisolintetralin monoacetate (4) and dihydroclusin monoacetate (5), have been isolated from the resin of Bursera fagaroides, together with two known ones, 2,3-demethoxy-secoisolintetralin diacetate (2) and dihydroclusin diacetate (3). The complete structure assignments were obtained by means of (1)H and (13)C NMR spectra.

Synthesis of azanucleosides through regioselective ring-opening of epoxides catalyzed by sulphated zirconia under microwave and solvent-free conditions.

New azanucleosides were obtained using sulphated zirconia (ZS) as catalyst in the nucleophilic oxirane ring opening reaction of 1-allyl-3-(oxiran-2-ylmethyl) pyrimidine-2,4(1H,3H)-dione and 1-allyl-5-methyl-3-(oxiran-2-ylmethyl)-pyrimidine-2,4(1H,3H)-dione, with (S)-prolinol. The new templates were obtained with good yields following a route which exploits the reactivity of epoxides in the presence of sulphated zirconia as catalyst. The key step was carried out using microwave and solvent-free conditions and proceeds with high selectivity.

Structure of salvioccidentalin, a diterpenoid with a rearranged neo-clerodane skeleton from Salvia occidentalis.

From the aerial parts of Salvia occidentalis (Labiatae) a new diterpenoid with a rearranged neo-clerodane skeleton was isolated. This new compound was named salvioccidentalin and its structure was established by spectroscopic means. A probable biogenetic relationship with salvigenolide from S. fulgens and salvileucalin A and spiroleucantholide from Salvia leucantha is proposed.

A new languidulane diterpenoid from Salvia mexicana var. mexicana.

From the aerial parts of Salvia mexicana var. mexicana, two C-10 epimers (α and ß) of salvimexicanolide were isolated. Our interpretation of the data, especially the 13C NMR, led us to conclude that the previously described 13C-NMR spectrum of the α-epimer was not accurately assigned and it actually corresponds to the ß-epimer. The structures proposed for the salvimexicanolides were verified by means of NOESY experiments. Dugesin B, arbutin, naringenin and the mixture of oleanolic and ursolic acids were also isolated from this Salvia spp.

Effects of bentonite on p-methoxybenzyl acetate: a theoretical model for oligomerization via an electrophilic-substitution mechanism.

Tonsil Actisil FF, a commercial bentonitic clay, promotes the formation of a series of electrophilic-aromatic-substitution products from para-methoxybenzyl acetate in carbon disulfide. The molecules obtained correspond to linear isomeric dimers, trimers, tetramers and a pentamer, according to their spectroscopic data. A clear indication of the title mechanistic pathway for the oligomerization growth was obtained from the analysis of a set of computational-chemistry calculations using the density-functional-theory level B3LYP/6-311++G(d,p). The corresponding conclusions were based on the computed dipole moments, the HOMO/LUMO distributions, and a natural-populations analysis of the studied molecules.

Oligomerization of 3,5-dimethyl benzyl alcohol promoted by clay: experimental and theoretical study.

Linear oligomerization of 3,5-dimethyl benzyl alcohol is induced by a montmorillonite clay (Tonsil Optimum Extra), producing 1,3,5,7-tetramethyl-9,10-dihydro-anthracene, which, by loss of protons results in the product 1,3,5,7-tetramethylanthracene. It was also found that the compounds 4-(3´,5´-dimethylbenzyl)-1,3,5,7-tetramethyl-9,10-dihydroanthracece and 4-(3´,5´-dimethylbenzyl)-1,3,5,7-tetra-methylanthracene were formed from 1,3,5,7-tetramethyl-9,10-dihydroanthracene. 1,3,5,7-Tetramethylanthryl radical cation was formed from 1,3,5,7-tetramethyl-9,10-dihydroanthracene; it was characterized by Electronic Paramagnetic Resonance (EPR). On the other hand, a theoretical analysis was performed, allowing the rationalization of the observed products and some of the key reaction steps.

Highly efficient macrolactonization of ω-hydroxy acids using benzotriazole esters: synthesis of Sansalvamide A.

A facile and mild macrolactonization reaction of ω-hydroxy acids was developed based on the transesterification of benzotriazole esters. Treatment of ω-hydroxy acids with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and 1-hydroxy benzotriazole (HOBT) in chloroform provided macrolactones in excellent yields. The reactions were performed under basic, neutral and acidic conditions using N,N-dimethylaminopyridine (DMAP), tetrabutylammonium tetrafluoroborate (TBABF(4)) and BF(3)·Et(2)O, respectively. A calcined hydrotalcite was also used instead of DMAP. Finally, to test the scope of the protocol in the synthesis of biologically relevant macrolactones, the total synthesis of Sansalvamide A was carried out.

Homoisoflavanones from Agave tequilana Weber.

Three homoisoflavanones were isolated from the "piña" and leaves of Agave tequilana Weber. The compounds were identified as: 5,7-dihydroxy-3-(4-methoxybenzyl)-chroman-4-one (1), 7-hydroxy-3-(4-hydroxybenzyl)-chroman-4-one (2) and 4'-demethyl-3,9-dihydro-punctatin (3). This is the first phytochemical study carried out to Agave tequilana Weber.

Asymmetric sulfur ylide based enantioselective synthesis of D-erythro-sphingosine.

An asymmetric sulfur ylide reaction was employed to prepare an epoxide intermediate in a convergent manner. This epoxide was efficiently transformed into D-erythro-sphingosine.

Stannyl ceramides as efficient acceptors for synthesising beta-galactosyl ceramides.

beta-Galactosyl ceramides have been obtained in excellent yields and stereoselectivities by reacting disarmed glycosyl donors with stannyl ethers. The broad compatibility of stannyl ethers with various leaving group-promoter pairs is demonstrated.

Highly efficient and stereoselective synthesis of beta-glycolipids.

beta-Galactosylceramide and glycolipid analogues were prepared in high yield and with complete chemo and stereoselectivity by reaction of alpha-iodo glycosides with stannyl ceramides, formed in situ. TBAI was used to activate both the iodogalactose and the stannyl ether.

Recent advances in the glycosylation of sphingosines and ceramides.

Glycosphingolipids (GSLs) are ubiquitous components of eukaryotic cell membranes. They are highly bioactive and are involved in many aspects of cell signalling like cell-cell interaction, cell-substratum interaction and cell-pathogen interaction. GSLs also are involved in the modulation of signal transduction, resulting in regulation of cell proliferation and differentiation. The biological importance and complexity of these compounds afford many opportunities to prepare synthetic analogues for studies of their metabolism in intra- and intercellular processes. This review focuses on recent contributions in the synthesis of GSLs, highlighting improvements in glycosylation reactions leading to alpha and beta glycosyl sphingosines and ceramides and related compounds. Literature from 2000 to the present is covered. The glycosylation reactions leading to the synthesis of GSLs are classified in function of the configuration of the created glycosidic bond (alpha or beta) and of the acceptor used, either azido-sphingosine or ceramide.

Aportación de la tomografía por emisión de positrones a la detección y estadificación del cáncer de mama / Contribution of positron emission tomography to the detection and staging of breast cancer

Introducción. La tomografía por emisión de positrones con 18F-fluorodeoxiglucosa (PET-FDG) es una técnica de diagnóstico por la imagen con numerosas aplicaciones en el campo de la oncología. En el cáncer de mama, concretamente, una de sus indicaciones más prometedoras es la estadificación no invasiva, tanto de la afección ganglionar como a distancia, lo cual tendría importantes repercusiones pronósticas y terapéuticas. Material y método. Se ha realizado una revisión de la bibliografía disponible sobre la utilidad de la PETFDG en la detección y estadificación del cáncer de mama. Se incluyen los resultados de la experiencia propia en nuestro centro. Resultados. La PET-FDG tiene especial interés para la detección de tumores en mamas densas, para la determinación de lesiones múltiples y para las mamas protésicas. En la estadificación ganglionar, la PET-FDG presenta una baja sensibilidad, por lo que no puede sustituir el estudio histológico y del ganglio centinela, pero es más exacta que otros métodos no invasivos y es especialmente útil en la valoración de la cadena mamaria interna. En la estadificación a distancia, la PET-FDG puede reemplazar y optimizar otros métodos de imagen habituales, sobre todo en casos de afección locorregional avanzada, elevación de marcadores tumorales y en la caracterización de hallazgos dudosos en la imagen anatómica o gammagráfica. Conclusiones. La PET-FDG tiene un importante impacto en el estudio de extensión del cáncer de mama, y complementa e incluso sustituye la información aportada por otras técnicas diagnósticas; asimismo, modifica el estadio tumoral en un elevado número de pacientes (AU)

Introduction. 18F-Fluorodeoxyglucose positron emission tomography (FDG-PET) is a diagnostic imaging tool with multiple applications in oncology. One of the more promising applications in breast cancer is noninvasive lymph node staging and detection of distant metastases, which may provide useful information about prognosis and treatment response. Material and method. Published studies on FDGPET applications in breast cancer detection and staging were reviewed. We also present our own experience in patients referred for preoperative staging of breast cancer. Results. FDG-PET is very useful in evaluating dense breasts, multicentric disease and breast prostheses. The sensitivity of FDG-PET for nodal staging is low, and consequently it cannot replace either sentinel lymph node biopsy or histologic examination. However, it is more accurate than another noninvasive techniques and is very useful in internal mammary node chain evaluation. FDG-PET can improve and maybe replace conventional imaging in detecting metastatic disease, especially in high risk patients with locoregionally advanced recurrent breast cancer or increased serum tumor markers, and helps to characterize unclear findings of anatomic imaging techniques or scintigraphy. Conclusions. FDG-PET is useful in breast cancer staging. It complements and even improves information from other diagnostic techniques and changes therapeutic management in a high proportion of patients (AU)

[Contribution of positron emission tomography to the detection and staging of breast cancer]. / Aportación de la tomografía por emisión de positrones a la detección y estadificación del cáncer de mama.

INTRODUCTION: 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is a diagnostic imaging tool with multiple applications in oncology. One of the more promising applications in breast cancer is noninvasive lymph node staging and detection of distant metastases, which may provide useful information about prognosis and treatment response. MATERIAL AND METHOD: Published studies on FDG-PET applications in breast cancer detection and staging were reviewed. We also present our own experience in patients referred for preoperative staging of breast cancer. RESULTS: FDG-PET is very useful in evaluating dense breasts, multicentric disease and breast prostheses. The sensitivity of FDG-PET for nodal staging is low, and consequently it cannot replace either sentinel lymph node biopsy or histologic examination. However, it is more accurate than another noninvasive techniques and is very useful in internal mammary node chain evaluation. FDG-PET can improve and maybe replace conventional imaging in detecting metastatic disease, especially in high risk patients with locoregionally advanced recurrent breast cancer or increased serum tumor markers, and helps to characterize unclear findings of anatomic imaging techniques or scintigraphy. CONCLUSIONS: FDG-PET is useful in breast cancer staging. It complements and even improves information from other diagnostic techniques and changes therapeutic management in a high proportion of patients.