920 resultados para Ring-opening


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A regioselective synthesis of unsymmetrical biaryls with electron withdrawing or donating substituents is described and illustrated by carbanion-induced ring transfonnation of 6-aryl-a-pyrones with methoxyacetone in excellent yield. Our methodology is an alternative to classical organometal-catalyzed aryl-aryl coupling reactions and can be applied to the synthesis of functionally demanding naphthyl biaryls for the development of new ligands for asymetric synthesis

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An expeditious synthesis of several 2-amino-isophthalonitriles and their biaryl compounds is described and illustrated by carbanion-induced ring transformation of functionalized 2H-pyran-2-ones with malononitrile in excellent yields. The strength of the reaction lies in the creation of an aromatic ring at room temperature from six membered-lactones under mild reaction conditions. This approach is an alternative to Diels-Alder reactions of 2H-pyran-2-ones with dienophiles, which require forcing thermal conditions to obtain benzene derivatives.

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A novel DBU-promoted ring transformation of substituted isoxazoles to substituted pyrroles is described

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Tributyltin hydride-mediated straightforward synthesis of a new isoxazolo-benzazulene system from the derivatives afforded by the Baylis-Hillman reaction of 3-(2-bromophenyl)-4-isoxazolecarbaldehydes is described

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An expeditious synthesis of highly substituted benzenes with electron withdrawing or donating substituents is described and illustrated by carbanion-induced ring transformation of 2H-pyran-2-one with malononitrile in excellent yield. The novelty of the reaction lies in the creation of an aromatic ring at room temperature from six membered-lactones under mild reaction conditions.

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Humankind today is challenged by numerous threats brought about by global change. Climate has been and is being modified by human activities, which calls for mitigation and adaptation measures at an unprecedented scale. Natural resources have been degraded by human development by means of land cover and land use changes, for which protective and restoration measures have to be taken by land users and governments in most countries of the North and South. Low levels of economic development and insufficient policies in most developing countries have led to widespread poverty, which affects nearly half of the world’s population and directly threatens almost one billion people. Finally, uncontrolled economic growth has increased disparities between and within populations and has led to widespread environmental problems in many nations. Generating and sharing knowledge is a key to addressing such global challenges. Knowledge can be used to develop the best solutions and to avoid or repair threats. Research partnerships have proven to be suitable means to bridge the divides and disparities between knowledge societies and developing countries, thereby reducing gaps. Research partnerships are tools for further capacity development and thereby lead to societal empowerment. Institutional settings allowing for research partnerships are needed both in the North and the South, so that the different networks can work together in a long-term enabling environment.

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The article analyses the option of common Nordic Standards for social work education in these countries. The option is viewed through the lens of trends in education in the different countries. In the article the notion of an Integrated Field Model is used to indicate the starting point for a common model of education. This model covers the field characteristics of Denmark and Norway and their current move towards a more research-based education. It also covers the research characteristics of education in Finland, Iceland and Sweden and their current move towards a new field connection based on research-oriented education. Some thoughts on international requirements on comparability and compatibility in this setting are addressed in the final section.

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Earth observations (EO) represent a growing and valuable resource for many scientific, research and practical applications carried out by users around the world. Access to EO data for some applications or activities, like climate change research or emergency response activities, becomes indispensable for their success. However, often EO data or products made of them are (or are claimed to be) subject to intellectual property law protection and are licensed under specific conditions regarding access and use. Restrictive conditions on data use can be prohibitive for further work with the data. Global Earth Observation System of Systems (GEOSS) is an initiative led by the Group on Earth Observations (GEO) with the aim to provide coordinated, comprehensive, and sustained EO and information for making informed decisions in various areas beneficial to societies, their functioning and development. It seeks to share data with users world-wide with the fewest possible restrictions on their use by implementing GEOSS Data Sharing Principles adopted by GEO. The Principles proclaim full and open exchange of data shared within GEOSS, while recognising relevant international instruments and national policies and legislation through which restrictions on the use of data may be imposed.The paper focuses on the issue of the legal interoperability of data that are shared with varying restrictions on use with the aim to explore the options of making data interoperable. The main question it addresses is whether the public domain or its equivalents represent the best mechanism to ensure legal interoperability of data. To this end, the paper analyses legal protection regimes and their norms applicable to EO data. Based on the findings, it highlights the existing public law statutory, regulatory, and policy approaches, as well as private law instruments, such as waivers, licenses and contracts, that may be used to place the datasets in the public domain, or otherwise make them publicly available for use and re-use without restrictions. It uses GEOSS and the particular characteristics of it as a system to identify the ways to reconcile the vast possibilities it provides through sharing of data from various sources and jurisdictions on the one hand, and the restrictions on the use of the shared resources on the other. On a more general level the paper seeks to draw attention to the obstacles and potential regulatory solutions for sharing factual or research data for the purposes that go beyond research and education.