- Evolution of N-Heterocycle-Substituted Iodoarenes (NHIAs) to Efficient Organocatalysts in Iodine(I/III)-Mediated Oxidative Transformations
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The reactivity of ortho-functionalized N-heterocycle-substituted iodoarenes (NHIAs) as organocatalysts in iodine(I/III)-mediated oxidations was systematically investigated in the α-tosyloxylation of ketones as the model reaction. During a systematic catalyst evolution, it was found that NH-triazoles and benzoxazoles have the most significant positive influence on the reactivity of the central iodine atom. A further catalyst improvement which focused on the substitution pattern of the arene revealed a remarkable ortho-effect. By introduction of an o-OMe group we were able to generate a novel NHIA with a so far unseen catalytic efficiency. This new catalyst is not only easy to synthesize but also enabled the α-tosyloxylation of carbonyl compounds at the lowest reported catalyst loading of only 1 mol%. Finally, the performance of this iodine(I) catalyst was successfully demonstrated in intramolecular oxidative couplings of biphenyls and oxidative rearrangements. (Figure presented.).
- Boelke, Andreas,Nachtsheim, Boris J.
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supporting information
p. 184 - 191
(2019/12/11)
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- Iodolopyrazolium Salts: Synthesis, Derivatizations, and Applications
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The synthesis of iodolopyrazolium triflates via an oxidative cyclization of 3-(2-iodophenyl)-1H-pyrazoles is described. The reaction is characterized by a broad substrate scope, and various applications of these novel cyclic iodolium salts acting as useful synthetic intermediates are demonstrated, in particular in site-selective ring openings. This was finally applied to generate derivatives of the anti-inflammatory drug celecoxib. Their application as highly active halogen-bond donors is shown as well.
- Boelke, Andreas,Caspers, Lucien D.,Kuczmera, Thomas J.,Lork, Enno,Nachtsheim, Boris J.
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supporting information
p. 7261 - 7266
(2020/10/05)
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- Copper-catalyzed domino reaction of carbodiimides and benzoic acid derivatives for the synthesis of quinazolinediones
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Quinazolinediones were obtained from 2-iodobenzoic acids and carbodiimide derivatives under mild reaction conditions via a copper-catalyzed domino reaction. The absence of an external base was essential to avoid the generation of amide by-products. Both alkyl- and aryl-substituted carbodiimides gave the corresponding quinazolinediones. However, the use of aryl-substituted carbodiimides resulted in low yields due to an undesired elimination process.
- Duangjan, Chanikan,Rukachaisirikul, Vatcharin,Saithong, Saowanit,Kaeobamrung, Juthanat
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supporting information
p. 3537 - 3540
(2018/08/29)
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- Copper-Catalyzed C(sp3)-S Bond and C(sp2)-S Bond Cross-Coupling of 2-(2-Iodobenzoyl) Substituted or 2-(2-Iodobenzyl) Substituted 1,2,3,4-Tetrahydroisoquinolines with Potassium Sulfide: Synthesis of Isoquinoline-Fused 1,3-Benzothiazine Scaffolds
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The sulfuration reaction of 2-(2-iodobenzoyl) substituted, or 2-(2-iodobenzyl) substituted 1,2,3,4-tetrahydroisoquinolines with potassium sulfide proceeded in the presence of copper catalysts to give tetrahydroisoquinoline-fused 1,3-benzothiazine scaffolds in moderate to appropriate yields. This protocol provided an efficient and simple strategy to construct the corresponding benzothiazine derivatives via formation of C(sp3)-S bond and C(sp2)-S bond, which the C-S bonds formed via different routes in this reaction (traditional cross-coupling reaction via the cleavage of C-I bond and oxidative cross-coupling reaction via C(sp3)-H bond functionalization).
- Dang, Pan,Zheng, Zhilei,Liang, Yun
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p. 2263 - 2268
(2017/02/26)
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- Pd-Catalyzed Selective Synthesis of Cyclic Sulfonamides and Sulfinamides Using K2S2O5 as a Sulfur Dioxide Surrogate
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A variety of cyclic sulfonamides and sulfinamides could be selectively synthesized under Pd catalysis using haloarenes bearing amino groups and a sulfur dioxide (SO2) surrogate. The amount of base was key in determining the selectivity. Mechanistic studies revealed that sulfinamides were initially formed via an unprecedented formal insertion of sulfur monoxide and were oxidized to sulfonamides in the presence of an iodide ion and DMSO.
- Konishi, Hideyuki,Tanaka, Hiromichi,Manabe, Kei
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supporting information
p. 1578 - 1581
(2017/04/13)
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- Direct carbocyclizations of benzoic acids: Catalyst-controlled synthesis of cyclic ketones and the development of tandem aHH (acyl Heck-Heck) reactions
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The formation of exo-methylene indanones and indenones from simple ortho-allyl benzoic acid derivatives has been developed. Selective formation of the indanone or indenone products in these reactions is controlled by choice of ancillary ligand. This new process has a low environmental footprint as the products are formed in high yields using low catalyst loadings, while the only stoichiometric chemical waste generated from the reactants in the transformation is acetic acid. The conversion of the active cyclization catalyst into the Hermman-Beller palladacycle was exploited in a one-pot tandem acyl Heck-Heck (aHH) reaction, and utilized in the synthesis of donepezil. Carboxylic acids in aHH: Simple ortho-allyl benzoic acid derivatives have been utilized in an acyl Heck (aH) reaction to selectively form indanones and indenones. The conversion of the active cyclization catalyst into the Hermman-Beller palladacycle was exploited in a one-pot tandem acyl Heck-Heck (aHH) reaction to form two sp 2-sp2 bonds of (E)-trisubstituted olefins.
- Miles, Kelsey C.,Le, Chi,Stambuli, James P.
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supporting information
p. 11336 - 11339
(2014/10/16)
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- Palladium-catalyzed insertion of N-tosylhydrazones for the synthesis of isoindolines
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Isoindolines are synthesized by palladium-catalyzed coupling reaction of N-(2-iodobenzyl) anilines with α,β-unsaturated N-tosylhydrazones. The reaction has several potential advantages: (1) toleration of a wide range of functional groups, (2) easy to handle and with mild conditions, (3) enriches the isoindoline family, (4) two new bonds form in one step.
- Zhou, Ping-Xin,Luo, Jian-Yi,Zhao, Lian-Biao,Ye, Yu-Ying,Liang, Yong-Min
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supporting information
p. 3254 - 3256
(2013/05/08)
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- Twist does a twist to the reactivity: Stoichiometric and catalytic oxidations with twisted tetramethyl-IBX
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The methyl groups in TetMe-IBX lower the activation energy corresponding to the rate-determining hypervalent twisting (theoretical calculations), and the steric relay between successive methyl groups twists the structure, which manifests in significant solubility in common organic solvents. Consequently, oxidations of alcohols and sulfides occur at room temperature in common organic solvents. In situ generation of the reactive TetMe-IBX from its precursor iodo-acid, i.e., 3,4,5,6-tetramethyl-2-iodobenzoic acid, in the presence of oxone as a co-oxidant facilitates the oxidation of diverse alcohols at room temperature.
- Moorthy, Jarugu Narasimha,Senapati, Kalyan,Parida, Keshaba Nanda,Jhulki, Samik,Sooraj, Kunnikuruvan,Nair, Nisanth N.
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experimental part
p. 9593 - 9601
(2012/01/03)
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- Quantitating the effect of an ortho substituent on cyclization and intramolecular hydrogen-transfer reactions of aryl radicals
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Reduction of allyl 2-iodobenzyl malonates with triphenyltin hydrides generates aryl radicals that partition between 6-exo cyclization, 7-endo cyclization, and 1,5-hydrogen atom transfer. Rate constants for all of these processes are high (> 108 M-1 s-1), and the rates are only marginally reduced (33%) by the introduction of methyl group ortho to the reacting radical.
- Curran, Dennis P.,Fairweather, Neil
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p. 2972 - 2974
(2007/10/03)
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- Synthesis, Resolution, and Applications of 1,16-Dihydroxytetraphenylene as a Novel Building Block in Molecular Recognition and Assembly
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This paper concerns the synthesis of 1,16-dihydroxytetraphenylene (DHTP) (2) by employing a novel NBS bromination route. (±)-DHTP 2 was successfully resolved into its optical antipodes and converted to (±)-1,16-bis(diphenylphosphino)tetraphenylene (BPTP) (26), whose platinum complex BPTP-PtCl2 (27) was also obtained. As a hydrogen bond donor, racemic and optically active DHTP 2 was allowed to assemble with 4,4′-bipyridine to form single crystals of good quality. X-ray Diffraction studies of these crystals revealed that the crystallographic packing of the hydrogen bonded complex between (±)-2 and 4,4′-bipyridine was different from the one formed from (S)-2 and 4,4′-bipyridine. It was found that an infinite zigzag chain with alternate chirality was formed in the assembly of (±)-2 and 4,4′-bipyridine, while (S)-2 and 4,4′-bipyridine failed to show the same assembly pattern. The reason (±)-2 formed an alternate and zigzag chain with 4,4′-bipyridine was most likely due to the inherent stability of this supramolecular assembly. The chiral recognition between 2 and optically active BINAP under the direction of platinum(II) has also been examined. 1H and 31P NMR spectroscopic studies demonstrated that there was an obvious discrimination of 2 between the enantiomers of BINAP-PtCO3.
- Wen, Jian-Feng,Hong, Wei,Yuan, Ke,Mak, Thomas C. W.,Wong, Henry N. C.
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p. 8918 - 8931
(2007/10/03)
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- A highly enantioselective intramolecular heck reaction with a monodentate ligand
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An efficient enantioselective intramolecular Heck reaction of cyclohexadienones, using readily available and modular TADDOL-based mono- and bidentate phosphoramidites as chiral ligands and not requiring any additives, has been developed. Excellent enantio
- Imbos, Rosalinde,Minnaard, Adriaan J.,Feringa, Ben L.
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p. 184 - 185
(2007/10/03)
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- Practical Method for the Synthesis and Optical Resolution of Axially Dissymmetric 6,6'-Dimethylbiphenyl-2,2'-dicarboxylic Acid
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Racemic 6,6'-dimethylbiphenyl-2,2'-dicarboxylic acid (1) could be conveniently synthesized and efficiently resolved by the recrystallization of the brucine salts in satisfactory yields.Each enantiomer, thus obtained, was confirmed to be optically pure from a high-performance liquid chromatographic (HPLC) analysis on an optically active column.
- Kanoh, Shigeyoshi,Muramoto, Hiroki,Kobayashi, Natsumi,Motoi, Masatoshi,Suda, Hiroshi
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p. 3659 - 3662
(2007/10/02)
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