176 research outputs found

    A one-pot Suzuki-hydrogenolysis protocol for the modular synthesis of 2,5-diaryltetrazoles

    Get PDF
    2,5-Diaryltetrazoles are a diverse range of compounds of considerable interest within the field of photochemistry as a valuable precursor of the nitrile imine 1,3-dipole. Current literature approaches toward this heterocycle remain unsuitable for the practical synthesis of a library of these derivatives. Herein, we disclose the development of a modular approach toward 2,5-diaryltetrazoles compatible with an array-type protocol, facilitated by a tandem Suzuki-hydrogenolysis approach

    The politics of prisoner legal rights

    Get PDF
    The article begins by locating human rights law within the current political context before moving on to critically review judicial reasoning on prisoner legal rights since the introduction of the Human Rights Act 1998. The limited influence of proportionality on legal discourses in England and Wales is then explored by contrasting a number of judgments since October 2000 in the domestic courts and European Court of Human Rights (ECtHR). The article concludes with a discussion of the implications of the restricted interpretation of legal rights for penal reform and proposes an alternative radical rearticulation of the politics of prisoner human rights

    Palladium-catalyzed synthesis of aryl amides through silanoate-mediated hydrolysis of nitriles

    Get PDF
    A procedure for the formation of aryl amides through the palladium-catalyzed coupling of nitriles and aryl bromides, via the formation of intermediary silanoate derived imidate species is reported. Optimization was undertaken and examples of the process are described that furnish the products in up to 86% isolated yield

    Transition metal-free coupling of 1,3-dipoles and boronic acids as a sustainable approach to C-C bond formation

    Get PDF
    The need for alternative, complementary approaches to enable C-C bond formation within organic chemistry is an on-going challenge in the area. Of particular relevance are transformations that proceed in the absence of transition metal reagents. In the current study, we report a comprehensive investigation of the coupling of nitrile imines and aryl boronic acids as an approach towards sustainable C-C bond formation. In situ generation of the highly reactive 1,3-dipole facilitates a Petasis-Mannich-type coupling via a nucleophilic boronate complex. The introduction of hydrazonyl chlorides as a complementary nitrile imine source to the 2,5-tetrazoles previously reported by our laboratory further broadens the scope of the approach. Additionally, we exemplify for the first time the extension of this protocol into another 1,3-dipole, through the synthesis of aryl ketone oximes from aryl boronic acids and nitrile Noxides

    Recent advances in the generation of nitrilium betaine 1,3-dipoles

    Get PDF
    Nitrilium betaine 1,3-dipoles are ubiquitous reagents in organic chemistry, with applications ranging from natural product synthesis to materials science. Given the high reactivity of these zwitterionic motifs, they are invariably generated in situ from a suitable precursor, prior to use. This short review summarises the recent progress in the development of modern approaches towards the formation of these 1,3-dipoles, and their applications within a diverse range of fields

    Metal free C-C bond formation via coupling of nitrile imines and boronic acids

    Get PDF
    The challenges of developing sustainable methods of carbon-carbon bond formation remains a topic of considerable importance in synthetic chemistry. Capitalizing on the highly reactive nature of the nitrile imine 1,3-dipole, we have developed a novel metal-free coupling of this species with aryl boronic acids. Photochemical generation of a nitrile imine intermediate and trapping with a palette of boronic acids enabled rapid and facile access to a broad library of more than 25 hydrazone derivatives in up to 92 % yield, forming a carbon-carbon bond in a metal free fashion. This represents the first reported example of direct reaction between boronic acids and a 1,3-dipole

    Descent with modification: critical use of historical evidence for conservation

    Get PDF
    The clear evidence of the accumulating impacts of anthropogenic actions on the Earth system is driving researchers to look to historical data as a resource for understanding the present and predicting the future. In the conservation science literature, using historical sources usually refers to data mining ‘the past’ using the scientific methods of historical ecology. This paper considers the often overlooked methodological challenges of sourcing and interpreting historical data. A schema is provided for conservation scientists, summarising the kinds of questions and metadata required to work rigorously with historical data. This will improve the accuracy of the data we use to construct trends to inform our understanding of the conservation status of particular species and ecosystems. It will also deepen our understanding of the interplays of factors influencing policy and management in particular social-ecological contexts

    Efficient Coding Theory Predicts a Tilt Aftereffect from Viewing Untilted Patterns

    Get PDF
    The brain is bombarded with a continuous stream of sensory information, but biological limitations on the data-transmission rate require this information to be encoded very efficiently [1]. Li and Atick [2] proposed that the two eyes? signals are coded efficiently in the brain using mutually decorrelated binocular summation and differencing channels; when a channel is strongly stimulated by the visual input, such that sensory noise is negligible, the channel should undergo temporary desensitization (known as adaptation). To date, the evidence for this theory has been limited [3 and 4], and the binocular differencing channel is missing from many models of binocular integration [5, 6, 7, 8, 9 and 10]. Li and Atick?s theory makes the remarkable prediction that perceived direction of tilt (clockwise or counterclockwise) of a test pattern can be controlled by pre-exposing observers to visual adaptation patterns that are untilted or even have no orientation signal. Here, we confirm this prediction. Each test pattern consisted of different images presented to the two eyes such that the binocular summation and difference signals were tilted in opposite directions, to give ambiguous information about tilt; by selectively desensitizing one or other of the binocular channels using untilted or non-oriented binocular adaptation patterns, we controlled the perceived tilt of the test pattern. Our results provide compelling evidence that the brain contains binocular summation and differencing channels that adapt to the prevailing binocular statistics
    • …
    corecore