- Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
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Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
- Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
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p. 5022 - 5037
(2021/05/04)
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- Amide Effects in C?H Activation: Noncovalent Interactions with L-Shaped Ligand for meta Borylation of Aromatic Amides
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A new concept for the meta-selective borylation of aromatic amides is described. It has been demonstrated that while esters gave para borylations, amides lead to meta borylations. For achieving high meta selectivity, an L-shaped bifunctional ligand has been employed and engages in an O???K noncovalent interaction with the oxygen atom of the moderately distorted amide carbonyl group. This interaction provides exceptional control for meta C?H activation/borylation.
- Bisht, Ranjana,Hoque, Md Emdadul,Chattopadhyay, Buddhadeb
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p. 15762 - 15766
(2018/11/10)
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- Bifunctional organocatalysts for the asymmetric synthesis of axially chiral benzamides
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Bifunctional organocatalysts bearing amino and urea functional groups in a chiral molecular skeleton were applied to the enantioselective synthesis of axially chiral benzamides via aromatic electrophilic bromination. The results demonstrate the versatilit
- Miyaji, Ryota,Wada, Yuuki,Matsumoto, Akira,Asano, Keisuke,Matsubara, Seijiro
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supporting information
p. 1518 - 1523
(2017/08/14)
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- Direct Hydroxylation and Amination of Arenes via Deprotonative Cupration
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Deprotonative directed ortho cupration of aromatic/heteroaromatic C-H bond and subsequent oxidation with t-BuOOH furnished functionalized phenols in high yields with high regio- and chemoselectivity. DFT calculations revealed that this hydroxylation reaction proceeds via a copper (I → III → I) redox mechanism. Application of this reaction to aromatic C-H amination using BnONH2 efficiently afforded the corresponding primary anilines. These reactions show broad scope and good functional group compatibility. Catalytic versions of these transformations are also demonstrated.
- Tezuka, Noriyuki,Shimojo, Kohei,Hirano, Keiichi,Komagawa, Shinsuke,Yoshida, Kengo,Wang, Chao,Miyamoto, Kazunori,Saito, Tatsuo,Takita, Ryo,Uchiyama, Masanobu
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supporting information
p. 9166 - 9171
(2016/08/05)
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- Bifunctional organocatalysts for the enantioselective synthesis of axially chiral isoquinoline n -oxides
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Bifunctional catalysts bearing amino and urea functional groups have been applied for a novel, highly enantioselective synthesis of axially chiral isoquinoline N-oxides, which are promising chiral ligands or organocatalysts in organic synthesis. This is t
- Miyaji, Ryota,Asano, Keisuke,Matsubara, Seijiro
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p. 6766 - 6769
(2015/06/16)
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- Enantioselective synthesis of atropisomeric benzamides through peptide-catalyzed bromination
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We report the enantioselective synthesis of atropisomeric benzamides employing catalytic electrophilic aromatic substitution reactions involving bromination. The catalyst is a simple tetrapeptide bearing a tertiary amine that may function as a Br?nsted base. A series of tri- and dibrominations were accomplished for a range of compounds bearing differential substitution patterns. Tertiary benzamides represent appropriate substrates for the reaction since they exhibit sufficiently high barriers to racemization after ortho functionalization. Mechanism-driven experiments provided some insight into the basis for selectivity. Examination of the observed products at low conversion suggested that the initial catalytic bromination may be regioselective and stereochemistry-determining. A complex between the catalyst and substrate was observed by NMR spectroscopy, revealing a specific association. Finally, the products of these reactions may be subjected to regioselective metal-halogen exchange and trapping with I2, setting the stage for utility.
- Barrett, Kimberly T.,Miller, Scott J.
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supporting information
p. 2963 - 2966
(2013/04/10)
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- [RhIIIcp*]-catalyzed dehydrogenative aryl-aryl bond formation
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Directed, undirected! Rhodium(III)-catalyzed double CH bond activation (one directed, one undirected) provides an efficient route to biaryls (see scheme; DG=directing group). Significant kinetic isotope effects for both reaction partners and H/D scrambling between them are interesting experimental findings. While the mechanism is still unclear, a rhodium(V) species is invoked in the catalytic cycle. Copyright
- Wencel-Delord, Joanna,Nimphius, Corinna,Patureau, Frederic W.,Glorius, Frank
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supporting information; experimental part
p. 2247 - 2251
(2012/04/10)
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- High-yielding, versatile, and practical [Rh(III)Cp*]-catalyzed ortho bromination and iodination of arenes
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We report a uniquely high-yielding, general, and practical ortho bromination and iodination reaction of different classes of aromatic compounds. This reaction occurs by Rh(III)-catalyzed C-H bond activation methodology and is therefore the first example of the application of this cationic catalyst for C-Br and C-I bond formation.
- Schroeder, Nils,Wencel-Delord, Joanna,Glorius, Frank
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supporting information; experimental part
p. 8298 - 8301
(2012/06/29)
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- Contra-Friedel-Crafts tert-butylation of substituted aromatic rings via directed metallation and sulfinylation
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Directed metallation and sulfinylation yields sulfoxides which undergo ipso nucleophilic aromatic substitution with tertiary and secondary alkyllithiums, giving aromatic rings bearing alkyl groups generally incompatible with directed metallation methods and with regioselectivity complementary with classical Friedel-Crafts substitution. The Royal Society of Chemistry 2006.
- Clayden, Jonathan,Stimson, Christopher C.,Keenan, Martine
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p. 1393 - 1394
(2008/02/03)
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- Directed Ortho Metalations of Tertiary Benzamides Using Lactones as Electrophiles
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Directed ortho metalation of oxygenated tertiary benzamides using tert-butyllithium in THF/TMEDA at -78 deg C followed by the addition of a range of lactones afforded ortho-substituted keto-alcohols in good yield.
- Brenstrum, Timothy J.,Brimble, Margaret A.,Stevenson, Ralph J.
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p. 4897 - 4904
(2007/10/02)
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