- The Osmium(II)-Promoted Cycloaddition Reaction of Anisole and N-Methylmaleimide and Characterization of the η2-4H-Anisolium Intermediate
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Anisole, when complexed by pentaammineosmium(II), undergoes a cycloaddition with N-methylmaleimide which is shown to be nonconcerted.
- Kopach, Michael E.,Harman, W. Dean
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- Pd(II)/bipyridine catalyzed conjugate addition of arylboronic acids to α,β-unsaturated amides
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The Pd(II)/bipyridine-catalyzed conjugate addition of arylboronic acid to α,β-unsaturated amides was developed and optimized, and the reaction was proceeded smoothly in air. A series of arylboronic acid and α,β-unsaturated amide substrates were surveyed, and modest to excellent yields were given.
- Ji, Jiamin,Yang, Zhenyu,Liu, Rui,Ni, Yuxin,Lin, Shaohui,Pan, Qinmin
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supporting information
p. 2723 - 2726
(2016/06/09)
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- Rhodium-catalyzed heck-type coupling of boronic acids with activated alkenes in an aqueous emulsion
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Intermolecular couplings between arylboronic acids and activated alkenes catalyzed by a water-soluble tert-bulyl amphosrhodium complex were found to progress at room temperature and generated Heck-type products with high yields and excellent selectivity. Substitution on the alkene component encouraged the formation of products arising from a conjugate addition-protonation process. In the case of Heck product formation, it was necessary to add two equivalents of the alkene component whereby one equivalent is believed to act as a sacrificial hydride acceptor.
- Lautens, Mark,Mancuso, John,Grover, Harpreet
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p. 2006 - 2014
(2007/10/03)
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- Michael addition reactions with η2-coordinaied anisoles: Controlling the stereochemistry of the para and benzylic carbons
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Several η2-coordinated anisole complexes were treated with various Michael acceptors in the presence of a Lewis or Br?nsted acid to generate stable 4H-anisolium complexes. These reactions were found to proceed with high stereochemical control with predictable outcomes, provided that the moderate acid (NH2Ph2)OTf was used and the complex was dissolved in an acidic solution. The stereochemistry is shown to originate from an unexpectedly high preference for one coordination diastereomer of the anisole complex in the solid state and a Diels-Alder like transition state for the Michael reaction.
- Smith, Philip L.,Keane, Joseph M.,Shankman, Sarah E.,Chordia, Mahendra D.,Harman, W. Dean
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p. 15543 - 15551
(2007/10/03)
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- Synthesis of 3-methylthio-4-aryl-3-pyrroline-2,5-diones and 3-arylpyrolidine-2,5-diones by reaction of nitroketene dithioacetal with arylacetonitriles
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The reaction of nitroketene dithioacetal (1a), i.e., 2,2-bis(methylthio)-1-nitroethylene, with arylacetonitriles (2a-I) in the presence of the base like sodium hydroxide gave 4-nitrobut-2-enenitriles (3a-I) which were convened into 5-hydroxyimino-4-methylthio-3-phenyl-3-pyrrolin-2-ones (4a-i) under refluxing in methanol. Title compounds (5a-i) were readily obtained by the treatment of 4a-i with hydrochloric acid and were finally led to N-methylated products (6a-I) with methyl iodide. The reduction of maleimides (4 - 6) with zinc dust in acetic acid afforded the corresponding 3-arylpyrrolidine-2,5-diones (7a-i) that can be convened to pharmacologycally active compounds like mesembrines.
- Shigemitsu, Yasuhiro,Tominaga, Yoshinori
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p. 2257 - 2260
(2007/10/03)
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- Osmium-Promoted Electrophilic Substitution of Anisoles: A Versatile New Method for the Incorporation of Carbon Substituents
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A structurally and electronically diverse set of anisoles are dihapto-coordinated to the π-base pentaammineosmium(II) and treated with a variety of carbon electrophiles (e.g. Michael acceptors, acetals) After deprotonation of a 4H-anisolium intermediate with a tertiary amine base, C(4)-substituted anisole complexes are isolated. The functionalized arenes are removed from the metal center either by mild heating or treatment with an oxidant (e.g. AgOTf, DDQ, CAN). The resulting substituted anisoles are isolated with yields ranging from 55-95%.
- Kolis, Stanley P.,Kopach, Michael E.,Liu, Ronggang,Harman, W. Dean
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p. 130 - 136
(2007/10/03)
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