| Metal-free, noncovalent catalysis of diels-alder reactions by neutral hydrogen bond donors in organic solvents and in water. | |
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MedLine Citation:
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PMID: 12532289 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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We examined the catalytic activity of substituted thioureas in a series of Diels-Alder reactions and 1,3-dipolar cycloadditions. The kinetic data reveal that the observed accelerations in the relative rates are more dependent on the thiourea substituents than on the reactants or solvent. Although the catalytic effectiveness is the strongest in noncoordinating, nonpolar solvents, such as cyclohexane, it is also present in highly coordinating polar solvents, such as water. In 1,3-dipolar cycloadditions, the thiourea catalysts demonstrate only very moderate selectivity for reactions with inverse electron demand. Our experiments emphasize that both hydrophobic and polar interactions can co-exist, making these catalysts active, even in highly coordinating solvents. This class of catalysts increases the reaction rates and endo-selectivities of Diels-Alder reactions, in a similar manner to weak Lewis acids, without concomitant product inhibition. |
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Authors:
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Alexander Wittkopp; Peter R Schreiner |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Chemistry (Weinheim an der Bergstrasse, Germany) Volume: 9 ISSN: 0947-6539 ISO Abbreviation: Chemistry Publication Date: 2003 Jan |
Date Detail:
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Created Date: 2003-01-17 Completed Date: 2003-04-29 Revised Date: 2009-08-04 |
Medline Journal Info:
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Nlm Unique ID: 9513783 Medline TA: Chemistry Country: Germany |
Other Details:
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Languages: eng Pagination: 407-14 Citation Subset: - |
Affiliation:
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Institut für Organische Chemie, Georg-August-Universität Göttingen Tammannstrasse 2, 37077 Göttingen, Germany. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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