- One-Pot C?H Functionalization of Arenes by Diaryliodonium Salts
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A transition-metal-free, mild, and highly regioselective synthesis of nitroarenes from arenes has been developed. The products are obtained in a sequential one-pot reaction by nitration of iodine(III) reagents with two carbon ligands, which are formed in situ from iodine(I). This novel concept has been extended to formation of aryl azides, and constitutes an important step towards catalytic reactions with these hypervalent iodine reagents. An efficient nitration of isolated diaryliodonium salts has also been developed, and the mechanism is proposed to proceed by a [2,2] ligand coupling pathway.
- Reitti, Marcus,Villo, Piret,Olofsson, Berit
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supporting information
p. 8928 - 8932
(2016/07/26)
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- Sterically Congested 2,6-Disubstituted Anilines from Direct C?N Bond Formation at an Iodine(III) Center
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2,6-Disubstituted anilines are readily prepared from the direct reaction between amides and diaryliodonium salts. As demonstrated for 24 different examples, the reaction is of unusually broad scope with respect to the sterically congested arene and the nitrogen source, occurs without the requirement for any additional promoter, and proceeds through a direct reductive elimination at the iodine(III) center. The efficiency of the coupling procedure is further demonstrated within the short synthesis of a chemerin binding inhibitor.
- Lucchetti, Nicola,Scalone, Michelangelo,Fantasia, Serena,Mu?iz, Kilian
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supporting information
p. 13335 - 13339
(2016/10/30)
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- Palladium(II) oxide impregnated on magnetite as a catalyst for the synthesis of 4-arylcoumarins: Via a Heck-arylation/cyclization process
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Heck-arylation/cyclization was achieved using heterogeneous palladium(ii) oxide impregnated on magnetite catalyst (2.5 mol%) with a lower catalyst loading than that reported for similar processes. Ethanol was used as a non-toxic and bio-renewable solvent. Good yields were afforded using a broad range of substrates (40-98%). The catalyst could be partially recycled, and analyses confirmed the almost total reduction of palladium(ii) oxide to palladium(0) as well as the iodine poissoning effect, which is the main barrier to complete recyclability.
- Pérez, Juana M.,Cano, Rafael,McGlacken, Gerard P.,Ramón, Diego J.
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p. 36932 - 36941
(2016/05/24)
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- Metal-free n -arylation of secondary amides at room temperature
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The arylation of secondary acyclic amides has been achieved with diaryliodonium salts under mild and metal-free conditions. The methodology has a wide scope, allows synthesis of tertiary amides with highly congested aryl moieties, and avoids the regioselectivity problems observed in reactions with (diacetoxyiodo)benzene.
- Tinnis, Fredrik,Stridfeldt, Elin,Lundberg, Helena,Adolfsson, Hans,Olofsson, Berit
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supporting information
p. 2688 - 2691
(2015/06/16)
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- A mild carbon-boron bond formation from diaryliodonium salts
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The direct metal-free borylation of diaryliodonium salts with diboron reagents is now demonstrated to be a feasible process toward formation of aryl boronic esters without any additive or catalysts, and it can be extended to a two-step C-C coupling of both aryl groups of the initial diaryliodonium reagent.
- Miralles,Romero,Fernández,Mu?iz
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supporting information
p. 14068 - 14071
(2015/09/15)
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- Pd/C as a catalyst for completely regioselective c=h functionalization of thiophenes under mild conditions
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The completely C3-selective arylation of thiophenes and benzo[b]thiophenes was achieved by using Pd/C as a heterogeneous catalyst without ligands or additives under mild reaction conditions. The practicability of this transformation is demonstrated by notable functional group tolerance and the insensitivity of the reaction to H2O and air. This method is also applicable to nitrogen- and oxygen-containing heterocycles, yielding the corresponding C2-arylated products. Three-phase tests along with Hg-poisoning and hot-filtration tests suggest that the catalytically active species is heterogeneous in nature. I+ can do better! Pd/C can be used without ligands or additives to catalyze the completely C3-selective arylation of diversely substituted thiophenes and benzo[b]thiophenes under mild reaction conditions. The physical nature of the catalytic species was investigated and the mechanism was studied. Relative rate data generated in a "robustness screen" were used to design a complex substrate that undergoes highly chemoselective sequential functionalization. Copyright
- Tang, Dan-Tam D.,Collins, Karl D.,Ernst, Johannes B.,Glorius, Frank
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supporting information
p. 1809 - 1813
(2014/03/21)
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- Metal-free arylation of oxygen nucleophiles with diaryliodonium salts
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Phenols and carboxylic acids are efficiently arylated with diaryliodonium salts. The reaction conditions are mild, metal free, and avoid the use of halogenated solvents, additives, and excess reagents. The products are obtained in good-to-excellent yields after short reaction times. Steric hindrance is very well tolerated, both in the nucleophile and diaryliodonium salt. The scope includes ortho- and halo-substituted products, which are difficult to obtain by metal-catalyzed protocols. Many functional groups are tolerated, including carbonyl groups, heteroatoms, and alkenes. Unsymmetric salts can be chemoselectively utilized to obtain products with hitherto unreported levels of steric congestion. The arylation has been extended to sulfonic acids, which can be converted to sulfonate esters by two different approaches. With recent advances in efficient synthetic procedures for diaryliodonium salts the reagents are now inexpensive and readily available. The iodoarene byproduct formed from the iodonium reagent can be recovered quantitatively and used to regenerate the diaryliodonium salt, which improves the atom economy. Copyright
- Jalalian, Nazli,Petersen, Tue B.,Olofsson, Berit
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supporting information
p. 14140 - 14149,10
(2012/12/12)
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- Metal-free synthesis of aryl esters from carboxylic acids and diaryliodonium salts
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An efficient arylation of carboxylic acids with diaryliodonium salts has been developed, giving aryl esters in high yields within short reaction times for both aromatic and aliphatic substrates. The transition-metal-free conditions are compatible with a range of functional groups, and good chemoselectivity is observed with unsymmetric diaryliodonium salts. Furthermore, steric hindrance in the ortho positions is well tolerated both in the carboxylic acid and in the diaryliodonium salt, yielding aryl esters that cannot be obtained via other esterification protocols.
- Petersen, Tue B.,Khan, Rehan,Olofsson, Berit
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supporting information; scheme or table
p. 3462 - 3465
(2011/08/07)
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- Cu(II)-catalyzed direct and site-selective arylation of indoles under mild conditions
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We have developed a new site-selective Cu(II)-catalyzed C-H bond functionalization process that can selectively arylate indoles at either the C3 or C2 position under mild conditions. The scope of the arylation process is broad and tolerates broad functionality on both the indole and aryl unit, which makes it amenable to further elaboration. The mechanism of the arylation reaction is proposed to proceed via a Cu(III)-aryl species that undergoes initial electrophilic addition at the C3 position of the indole motif. We speculate that site of indole arylation arises through a migration of the Cu(III)-aryl group from C3 to C2, and this can be controlled by the nature of the group on the nitrogen atom; free (NH)- and N-alkylindoles deliver the C3-arylated product, whereas N-acetylindoles afford the C2 isomer, both with excellent yield and selectivity. Copyright
- Phipps, Robert J.,Grimster, Neil P.,Gaunt, Matthew J.
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supporting information; experimental part
p. 8172 - 8174
(2009/02/02)
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