Stereoselective Acetate Aldol Reactions From Metal Enolates

This review deals with metal enolate-mediated stereoselective acetate aldol reactions. It summarizes recent advances on aldol additions of unsubstituted metal enolates from chiral auxiliaries, stoichiometric and catalytic Lewis acids, or acting in substrate- controlled reactions, which provide stereocontrolled aldol transformations that allow the efficient synthesis of structurally complex natural products.

Nucleophile-Catalyzed Additions to Activated Triple Bonds. Protection of Lactams, Imides, and Nucleosides with MocVinyl and Related Groups

Additions of lactams, imides, (S)-4-benzyl-1,3-oxazolidin-2-one, 2-pyridone, pyrimidine-2,4-diones (AZT derivatives), or inosines to the electron-deficient triple bonds of methyl propynoate, tert-butyl propynoate, 3-butyn-2-one, N-propynoylmorpholine, or N-methoxy-N-methylpropynamide in the presence of many potential catalysts were examined. DABCO and, second, DMAP appeared to be the best (highest reaction rates and E/Z ratios), while RuCl3, RuClCp*(PPh3)2, AuCl, AuCl(PPh3), CuI, and Cu2(OTf)2 were incapable of catalyzing such additions. The groups incorporated (for example, the 2-(methoxycarbonyl)ethenyl group that we name MocVinyl) serve as protecting groups for the above-mentioned heterocyclic CONH or CONHCO moieties. Deprotections were accomplished via exchange with good nucleophiles: the 1-dodecanethiolate anion turned out to be the most general and efficient reagent, but in some particular cases other nucleophiles also worked (e.g., MocVinyl-inosines can be cleaved with succinimide anion). Some structural and mechanistic details have been accounted for with the help of DFT and MP2 calculations.

Operacions bàsiques al laboratori químic en xarxa. Una nova eina per a estudiants i professors

Un conjunt de professors de les facultats de Química i Farmàcia de la Universitat de Barcelona hem elaborat un material docent en suport electrònic, d"accés lliure a la xarxa, que descriu el procediment pràctic de diverses operacions bàsiques de treball al laboratori químic. L"objectiu principal és crear un material docent que serveixi de suport a l"aprenentatge dels estudiants i a la tasca docent del professorat involucrat en l"ensenyament del treball pràctic en l"etapa d"inici dels estudis universitaris.

Tienda online de pita pinta

El proyecto consiste en la creación de un portal web para la venta de gallina de raza autóctona asturiana, pita pinta. El cliente, criador de esta raza, encarga esta web para dar a conocer su gallinero y ofrecer material relacionado con la cría y productos de alimentación, todo ello para su encargo y compra por internet.

Amazon.es : incògnites i expectatives. Amb Enric Faura i Pep Torn

Debat a l'Internauta, el primer programa de ràdio del país sobre la xarxa, una col·laboració entre la UOC i Vilaweb. Fa menys d'una setmana que es va confirmar la notícia: la plataforma de comerç electrònic més potent de la xarxa, Amazon, va obrir dimecres de la setmana passada la filial ibèrica. Amazon és actualment el portal de venda en línia més important i divers, amb un catàleg de milions de llibres impresos i electrònics, a més d'un gavadal de productes com ara compactes, DVD, jocs, aparells d'electrònica de consum i, fins i tot, roba, alimentació i mobiliari. De moment, Amazon.es ha aterrat a casa nostra amb una oferta de productes físics, entre els quals hi ha cinquanta mil llibres impresos en català, però obre tantes oportunitats com interrogants. Com afectarà les llibreries convencionals? Tindran mercat ara plataformes de llibre digital més modestes? Estimularà el negoci del llibre electrònic? Facilitarà l'autoedició de llibres? Farà créixer el nombre de lectors en català? En parlem amb Enric Faura, de la plataforma Edi.cat, i amb l'expert Pep Torn, director de l'àrea de Biblioteca i Recursos Documentals de la UOC.

Mobile Phone Use among Market Traders at Fairs in Rural Peru

We characterize market traders at two rural fairs in Puno, Peru, based on quantitative and qualitative data gathered in 2008, to gain insight into types of traders and the information needs that influence the degree to which they use mobile phones to make decisions regarding which weekly fairs to attend. Using variables such as origin, type of goods sold, means of transportation to the market, and reliance on networks, we identify traders as full-time traders, part-time traders, or subsistence traders, that is, people trading solely to survive. We find that when traders are already familiar with the technology, regularly rely on endogenous networks to make decisions, and have more to lose from failing to trade (e.g., those selling perishable goods), they are more likely to use mobile phones to decide where to sell.

Evaluation of spatial distribution of flatfish by laser scannig

Peer reviewed

Mitochondrial control region and microsatellite data show low genetic variability in reared senegalese sole, Solea senegalensis. Preliminary data

Peer reviewed

Study of fish swimming activity using Acoustical Doppler Velocimetry (ADV) techniques

Peer reviewed

Les transformacions de la masoveria gironina en el segle XX

Article que estudia les característiques i les transformacions de la masoveria durant el segle XX a les comarques gironines

Effect of Tocopherol Extract, Staphylococcus carnosus Culture, and Celery Concentrate Addition on Quality Parameters of Organic and Conventional Dry-Cured Sausages

The effects of the addition to sausage mix of tocopherols (200 mg/kg), a conventional starter culture with or without Staphylococcus carnosus, celery concentrate (CP) (0.23% and 0.46%), and two doses of nitrate (70 and 140 mg/kg expressed as NaNO(3)) on residual nitrate and nitrite amounts, instrumental CIE Lab color, tocol content, oxidative stability, and overall acceptability were studied in fermented dry-cured sausages after ripening and after storage. Nitrate doses were provided by nitrate-rich CP or a chemical grade source. The lower dose complies with the EU requirements governing the maximum for ingoing amounts in organic meat products. Tocopherol addition protected against oxidation, whereas the nitrate dose, nitrate source, or starter culture had little influence on secondary oxidation values. The residual nitrate and nitrite amounts found in the sausages with the lower nitrate dose were within EU-permitted limits for organic meat products and residual nitrate can be further reduced by the presence of the S. carnosus culture. Color measurements were not affected by the CP dose. Product consumer acceptability was not affected negatively by any of the factors studied. As the two nitrate sources behaved similarly for the parameters studied, CP is a useful alternative to chemical ingredients for organic dry-cured sausage production.

Europa als ulls dels Annales (1093-1933)

During this first third of this century, the continent of Europe witnessed far-reaching territorial transformations in the nineteenth century model. To some extent, the setting wich had inspired the epistemological structure of the French regional school was being replaced by one in which -at least to externa1 appearances- the relationship between the physical environment and human activities was much less evident. The adaptation of the theoretical and methodological context to the new Europe seems to take the form of a non-lineal evolution, for in the latter years of the period examined, evolutionary tendencies indicate a return to the more classical model. In this way, the growing interest which the publication had shown in Atlantic Europe and topics of a more economic nature, was truncated. The traditional settings --especially the Mediterranean- came to the fore again and interest in rural societies was renewed. Likewise, the monographic studies which had demonstrated distinct functional objectives in the midtwenties, recovered elements of ecological explanation, and the search for the relationship between environment and society

Turisme cultural en un espai rural

En els darrers quinze anys hem pogut constatar un lent creixement del turisme en els espais naturals i en els espais culturals. Ara, els escenaris rurals, els paisatges de muntanya mitjana, els nuclis rurals, els museus etnogràfics o les petites esglésies romàniques s'integren en el catàleg de productes turístics contemporanis, juntament amb les colònies Industrials, alguns centres comercials, espais d'oci programats o centres de producció

Mossos i criats: una radiografia del treball assalariat als masos (Girona, 1946)

L'objectiu d'aquest treball consisteix a analitzar el grup dels assalariats rurals estables a partir d'una relació de masos de la província de Girona elaborada amb finalitats polítiques i policials el 1946 per la 131ª Comandància de la Guardia Civil

Nucleophile-Catalyzed Additions to Activated Triple Bonds. Protection of Lactams, Imides, and Nucleosides with MocVinyl and Related Groups

Additions of lactams, imides, (S)-4-benzyl-1,3-oxazolidin-2-one, 2-pyridone, pyrimidine-2,4-diones (AZT derivatives), or inosines to the electron-deficient triple bonds of methyl propynoate, tert-butyl propynoate, 3-butyn-2-one, N-propynoylmorpholine, or N-methoxy-N-methylpropynamide in the presence of many potential catalysts were examined. DABCO and, second, DMAP appeared to be the best (highest reaction rates and E/Z ratios), while RuCl3, RuClCp*(PPh3)2, AuCl, AuCl(PPh3), CuI, and Cu2(OTf)2 were incapable of catalyzing such additions. The groups incorporated (for example, the 2-(methoxycarbonyl)ethenyl group that we name MocVinyl) serve as protecting groups for the above-mentioned heterocyclic CONH or CONHCO moieties. Deprotections were accomplished via exchange with good nucleophiles: the 1-dodecanethiolate anion turned out to be the most general and efficient reagent, but in some particular cases other nucleophiles also worked (e.g., MocVinyl-inosines can be cleaved with succinimide anion). Some structural and mechanistic details have been accounted for with the help of DFT and MP2 calculations.