C–O Bond Formation through Transition Metal-mediated Etherification

Lee, C.; Matunas, Robert

doi:10.1016/b0-08-045047-4/00136-9

Cited by 10 publications

(31 citation statements)

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“…The regiocontrol has been of great importance in allylic substitution . Recently, the iridium-catalyzed regioselective allylic amination of unsymmetrical acyclic substrates giving the branched products was studied by Takeuchi’s group .…”

Section: Resultsmentioning

confidence: 99%

“…Recently, the iridium-catalyzed regioselective allylic amination of unsymmetrical acyclic substrates giving the branched products was studied by Takeuchi’s group . Therefore, the iridium-catalyzed allylic substitution has been a subject of current interest. , Recently, important contributions in this area come from Helmchen and Hartwig. , …”

Section: Resultsmentioning

confidence: 99%

“…Asymmetric allylic substitutions have been developed as fundamentally important reactions. , The allylic amination of 1,3-symmetrical substrates has been widely studied including enantioselective versions. On the other hand, the allylic amination of unsymmetrical substrates is challenging, since both regio- and enantioselectivities should be controlled to give the desired branched products with high enantiopurity.…”

Section: Resultsmentioning

confidence: 99%

“…The pioneering work has been done by using chiral ferrocenylphosphine−palladium complexes by Hayashi and Ito . The regio- and stereoselectivities of allylic substitution with iridium catalyst are quite different from those of palladium-catalyzed amination. ,, In recent years, the control of regio- and enantioselectivities in iridium-catalyzed allylic amination and etherification has been mainly studied by Hartwig and Helmchen, respectively. Hence, the regio- and enantioselective allylic substitution with chiral iridium complex has been a subject of current interest. − …”

Section: Resultsmentioning

confidence: 99%

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Palladium- or Iridium-Catalyzed Allylic Substitution of Guanidines: Convenient and Direct Modification of Guanidines

et al. 2008

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As a convenient and direct functionalization of guanidines, the transition metal-catalyzed allylic substitution of guanidines was studied. The guanidine derivatives bearing two electron-withdrawing substituents acted as reactive nucleophiles in the allylic substitution to give the monoallylated products. The double allylic substitution was achieved by using tri-Boc-guanidine bearing three electron-withdrawing substituents as a nucleophile to give the diallylated products. The regiocontrol in the allylic substitution of unsymmetrical allylic substrates has been investigated by employing the palladium or iridium catalysts. The iridium complex of chiral pybox ligand allowed the regio- and enantioselective allylic substitution. Asymmetric double allylic substitution of tri-Boc-guanidine with phosphate bearing the 1-naphthyl group gave the diallylated product with high diastereo-, regio-, and enantioselectivities.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Palladium- or Iridium-Catalyzed Allylic Substitution of Guanidines: Convenient and Direct Modification of Guanidines

et al. 2008

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“…Etherification of oxygenated organic compounds is an ubiquitous organic transformation in both industrial and fine chemical syntheses. 1 Strong Brønsted acid and heterogeneous acid catalysts are commonly employed for industrial-scale etherification of alcohols, 2 while the Williamson ether synthesis has long been used for laboratory-scale synthesis of unsymmetrically substituted ethers. 3 Seminal catalytic C–O bond formation methods such as Ullmann-and Mitsunobu-type coupling reactions have been extensively utilized for the synthesis of aryl-substituted ethers.…”

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confidence: 99%

Chemoselective Formation of Unsymmetrically Substituted Ethers from Catalytic Reductive Coupling of Aldehydes and Ketones with Alcohols in Aqueous Solution

Kalutharage

2015

Org. Lett.

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A well-defined cationic Ru-H complex catalyzes reductive etherification of aldehydes and ketones with alcohols. The catalytic method employs environmentally benign water as the solvent and cheaply available molecular hydrogen as the reducing agent to afford unsymmetrical ethers in a highly chemoselective manner.Etherification of oxygenated organic compounds is an ubiquitous organic transformation in both industrial and fine chemical syntheses. 1 Strong Brønsted acid and heterogeneous acid catalysts are commonly employed for industrial-scale etherification of alcohols, 2 while the Williamson ether synthesis has long been used for laboratory-scale synthesis of unsymmetrically substituted ethers. 3 Seminal catalytic C-O bond formation methods such as Ullmann-and Mitsunobu-type coupling reactions have been extensively utilized for the synthesis of aryl-substituted ethers. 4 More recently, a number of highly effective catalytic methods for unsymmetrical ethers have been developed from use of hydroalkoxylation of alkenes 5 and oxidative C-H alkoxylation of arenes. 6 The reductive etherification of carbonyl compounds has also been shown to be a synthetically powerful etherification method, but this method requires a stoichiometric amount of silane as the reducing agent. 7 Despite such remarkable progress, these catalytic etherification methods pose major synthetic and environmental problems in that they employ reactive reagents such as inorganic acids and organic alkoxide substrates, which result in the formation of copious amounts of wasteful byproducts. From the viewpoint of achieving green and sustainable catalysis, the development of an efficient and broadly applicable catalytic etherification process that NOT THE PUBLISHED VERSION; this is the author's final, peer-reviewed manuscript. The published version may be accessed by following the link in the citation at the bottom of the page.Organic Letters, Vol 17, No. 7 (2015): pg. 1778-1781. DOI. This article is © American Chemical Society and permission has been granted for this version to appear in e-Publications@Marquette. American Chemical Society does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from American Chemical Society. 3does not form any wasteful byproducts remains a high priority goal, particularly for the synthesis of unsymmetrically substituted ethers. 8 We recently discovered that a well-defined cationic ruthenium hydride complex [(C6H6)(PCy3)(CO)RuH] + BF4 -(1) is a highly selective catalyst precursor for the etherification of two different alcohols to form unsymmetrically substituted ethers. 9 While this etherification provides unsymmetrical ethers without forming any wasteful byproducts, it was not effective for the coupling between electronically similar or sterically demanding aliphatic alcohols, as it gave a mixture of symmetrical and unsymmetrical ethers. In an effort to extend the scope of the etherification reaction, we explored the analogous reductiv...

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Nucleophilic Aliphatic Substitution

Westaway¹

2019

Organic Reaction Mechanisms Series

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C–O Bond Formation through Transition Metal-mediated Etherification

Cited by 10 publications

References 483 publications

Palladium- or Iridium-Catalyzed Allylic Substitution of Guanidines: Convenient and Direct Modification of Guanidines

Palladium- or Iridium-Catalyzed Allylic Substitution of Guanidines: Convenient and Direct Modification of Guanidines

Chemoselective Formation of Unsymmetrically Substituted Ethers from Catalytic Reductive Coupling of Aldehydes and Ketones with Alcohols in Aqueous Solution

Nucleophilic Aliphatic Substitution

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