97 research outputs found
Exploring mobile news reading interactions for news app personalisation
As news is increasingly accessed on smartphones and tablets, the need for personalising news app interactions is apparent. We report a series of three studies addressing key issues in the development of adaptive news app interfaces. We first surveyed users' news reading preferences and behaviours; analysis revealed three primary types of reader. We then implemented and deployed an Android news app that logs users' interactions with the app. We used the logs to train a classifier and showed that it is able to reliably recognise a user according to their reader type. Finally we evaluated alternative, adaptive user interfaces for each reader type. The evaluation demonstrates the differential benefit of the adaptation for different users of the news app and the feasibility of adaptive interfaces for news apps
Synthesis of marmycin A and investigation into its cellular activity
Anthracyclines such as doxorubicin are used extensively in the treatment of cancers. Anthraquinone-related angucyclines also exhibit antiproliferative properties and have been proposed to operate via similar mechanisms, including direct genome targeting. Here, we report the chemical synthesis of marmycin A and the study of its cellular activity. The aromatic core was constructed by means of a one-pot multistep reaction comprising a regioselective Diels-Alder cycloaddition, and the complex sugar backbone was introduced through a copper-catalysed Ullmann cross-coupling, followed by a challenging Friedel-Crafts cyclization. Remarkably, fluorescence microscopy revealed that marmycin A does not target the nucleus but instead accumulates in lysosomes, thereby promoting cell death independently of genome targeting. Furthermore, a synthetic dimer of marmycin A and the lysosome-targeting agent artesunate exhibited a synergistic activity against the invasive MDA-MB-231 cancer cell line. These findings shed light on the elusive pathways through which anthraquinone derivatives act in cells, pointing towards unanticipated biological and therapeutic applications
Palladium/Norbornene Catalytic System: Chelation as a Tool To Control Regioselectivity of Pd(IV) Reductive Elimination
Palladium/norbornene joint catalysis gives rise to a unique system in which the three most common formal oxidation states of the metal are at work in the same cycle (0, II, and IV). This paper summarizes a selection of synthetic applications and the feasibility of Pd(IV) formation by oxidative addition of aryl halides. On this intermediate, the presence of a suitable chelating group could trigger unexpected aryl–norbornyl coupling, further broadening the scope of readily available polycyclic framework
Radical Pd(III)/Pd(I) reductive elimination in palladium sequences
Open-shell mechanisms are often at work in catalytic sequences involving first-row transition metals while usually not considered in palladium chemistry. Herein a computational study suggests their possible relevance in catalytic methods involving paramagnetic Pd(III) intermediates. Indeed C–C bond forming reductive elimination previously thought to occur in Pd(IV) complexes has lower barriers in neutral, radical Pd(III) intermediates instead. These species could form upon addition on Pd(II) of an aryl radical generated via single electron transfer from a photo-active ruthenium complex and have the perfect stereoelectronic arrangement to smoothly undergo the coupling proces
Diastereoselective Synthesis of Dibenzoazepines through Chelation on Palladium(IV) Intermediates
Joint palladium/norbornene organometallic catalysis allows for straightforward access to dibenzo[c,e]azepines. These synthetically challenging polycyclic frameworks form in one pot via a three-component coupling of an aryl iodide, a bromobenzylamine, and an olefin. A key, atroposelective aryl–aryl coupling from chelated Pd(IV) intermediates dictates the outcome of the cascade. DFT modeling sheds light on the complex mechanism that allows the complete diasteroselectivity to be observe
Electrophilic activation of allenenes and allenynes: analogies and differences between Brønsted and Lewis acid activation
This Tutorial Review summarizes recent examples of electrophilic activation of allenes with particular focus on analogies and differences between Lewis and Brønsted acid activation of these versatile substrates. The aim of this article is to present a general overview of the possibilities offered to chemists using complementary modes of catalysis and to emphasize advantages and limitations of each approach, thereby providing a means to expand the scope of this powerful synthetic methodology
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