- Linear free energy relationships in the Bergman cyclization of 4-substituted-1,2-diethynylbenzenes
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A series of 4-substituted-1,2-diethylnylbenzenes were prepared (1a-f) and subjected to Bergman cyclization. Bulk cyclization proceeded to produce the corresponding 2-substituted naphthalenes (2a-f) in good yields (59-78%). Kinetic experiments show a linear free energy relationship between the cyclization rate and the Hammett σ(m) substituent coefficient and the Swain-Lupton field and resonance parameters. (C) 2000 Elsevier Science Ltd.
- Choy,Kim,Ballestero,Artigas,Diez,Lichtenberger,Shapiro,Russell
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Read Online
- Palladium-Catalyzed Cross-Coupling of Superbase-Generated C(sp3) Nucleophiles
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A range of methods has been investigated recently for the arylation of weakly acidic C(sp3)-H bonds, primarily exploiting directed metalation with a transition metal catalyst or radical formation via hydrogen atom transfer. In this work, a classical base-mediated approach is taken, exploiting the ability of organometallic superbases to metalate very weakly acidic (pKa> 40) C-H bonds. Conditions are developed with eithern-BuLi/diamine orn-BuLi/KOtBu superbases to enable metalation to occur with high selectivity. Organolithium nucleophiles can be directly used in cross-coupling, or organozincs can be formed to enable reactions with functional group-dense organohalides.
- Freure, Garrett P. R.,Lavertu, Jean-Danick E.,Newman, Stephen G.,Skrotzki, Eric A.
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p. 12258 - 12263
(2021/10/26)
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- Additive-freeN-methylation of amines with methanol over supported iridium catalyst
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An efficient and versatile zinc oxide-supported iridium (Ir/ZnO) catalyst was developed to catalyze the additive-freeN-methylation of amines with methanol. Mechanistic studies suggested that the high catalytic reactivity is rooted in the small sizes (1.4 nm) of Ir nanoparticles and the high ratio (93%) of oxidized iridium species (IrOx, Ir3+and Ir4+) on the catalyst. Moreover, the delicate cooperation between the IrOxand ZnO support also promoted its high reactivity. The selectivity of this catalyticN-methylation was controllable between dimethylation and monomethylation by carefully tuning the catalyst loading and reaction solvent. Specifically, neat methanol with high catalyst loading (2 mol% Ir) favored the formation ofN,N-dimethylated amine, while the mesitylene/methanol mixture with low catalyst loading (0.5 mol% Ir) was prone to producing mono-N-methylated amines. An environmentally benign continuous flow system with a recycled mode was also developed for the efficient production ofN-methylated amines. With optimal flow rates and amine concentrations, a variety ofN-methylamines were produced with good to excellent yields in this Ir/ZnO-based flow system, providing a starting point for the clean and efficient production ofN-methylamines with this cost-effective chemical process.
- Liu, Xiang,Loh, Teck-Peng,Qiang, Wenwen,Wang, Jing,Ye, Sen,Zhu, Longfei
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p. 3364 - 3375
(2021/06/06)
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- Nickel-Catalyzed Amination of Aryl Chlorides with Amides
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A nickel-catalyzed amination of aryl chlorides with diverse amides via C-N bond cleavage has been realized under mild conditions. A broad substrate scope with excellent functional group tolerance at a low catalyst loading makes the protocol powerful for synthesizing various aromatic amines. The aryl chlorides could selectively couple to the amino fragments rather than the carbonyl moieties of amides. Our protocol complements the conventional amination of aryl chlorides and expands the usage of inactive amides.
- Li, Jinpeng,Huang, Changyu,Wen, Daheng,Zheng, Qingshu,Tu, Bo,Tu, Tao
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supporting information
p. 687 - 691
(2021/01/09)
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- Photoinduced Deaminative Borylation of Unreactive Aromatic Amines Enhanced by CO2
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Herein, direct unreactive C-N borylation of aromatic amines by a photocatalyst was achieved. The C-N borylation of aromatic amines with bis(pinacolato)diboron (B2pin2) proceeded using a pyrene catalyst under light irradiation to afford desired borylated products and aminoborane as a byproduct. The yield of the borylated product improved under a CO2 atmosphere which probably reduced the inhibitory effect of aminoborane. Mechanistic studies suggested that the C-N bond cleavage and C-B bond formation proceeded via a concerted pathway.
- Shiozuka, Akira,Sekine, Kohei,Kuninobu, Yoichiro
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supporting information
p. 4774 - 4778
(2021/06/28)
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- Iron-Catalyzed Oxidative C?C Cross-Coupling Reaction of Tertiary Anilines with Hydroxyarenes by Using Air as Sole Oxidant
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A mild procedure for the oxidative C?C cross-coupling of tertiary anilines with phenols is described which provides the products generally in high yields and with excellent selectivity. The reaction is catalyzed by the hexadecafluorinated iron–phthalocyanine complex FePcF16 in the presence of substoichiometric amounts of methanesulfonic acid and ambient air as sole oxidant.
- Purtsas, Alexander,Kataeva, Olga,Kn?lker, Hans-Joachim
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p. 2499 - 2508
(2020/02/11)
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- Expedient Synthesis of N-Methyl- and N-Alkylamines by Reductive Amination using Reusable Cobalt Oxide Nanoparticles
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N-Methyl- and N-alkylamines represent important fine and bulk chemicals that are extensively used in both academic research and industrial production. Notably, these structural motifs are found in a large number of life-science molecules and play vital roles in regulating their activities. Therefore, the development of convenient and cost-effective methods for the synthesis and functionalization of amines by using earth-abundant metal-based catalysts is of scientific interest. In this regard, herein we report an expedient reductive amination process for the selective synthesis of N-methylated and N-alkylated amines by using nitrogen-doped, graphene-activated nanoscale Co3O4-based catalysts. Starting from inexpensive and easily accessible nitroarenes or amines and aqueous formaldehyde or aldehydes in the presence of formic acid, this cost-efficient reductive amination protocol allows the synthesis of various N-methyl- and N-alkylamines, amino acid derivatives, and existing drug molecules.
- Senthamarai, Thirusangumurugan,Murugesan, Kathiravan,Natte, Kishore,Kalevaru, Narayana V.,Neumann, Helfried,Kamer, Paul C. J.,Jagadeesh, Rajenahally V.
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p. 1235 - 1240
(2018/02/09)
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- C-O/C-H Coupling of Polyfluoroarenes with Aryl Carbamates by Cooperative Ni/Cu Catalysis
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Cross-coupling of polyfluoroarenes with aryl carbamates through the cleavage of both sp2 C-O and C-H bonds is reported. The reaction conditions are simple, and only transition-metal catalysts and ligands are essential. Mechanistic studies indicated that Ni catalyst played an important role in activating C-O bond, while the Cu one in activating C-H Bond. The developed system proved to be effective for cross-coupling of terminal alkynes with aryl carbamates.
- Wang, Yang,Wu, Song-Bai,Shi, Wen-Juan,Shi, Zhang-Jie
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supporting information
p. 2548 - 2551
(2016/07/06)
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- Heterogeneous Rhodium-Catalyzed Aerobic Oxidative Dehydrogenative Cross-Coupling: Nonsymmetrical Biaryl Amines
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The first heterogeneously catalyzed oxidative dehydrogenative cross-coupling of aryl amines is reported herein. 2-Naphthylamine analogues were reacted with various electron-rich arenes using a heterogeneous Rh/C catalyst under mild aerobic conditions, thus affording nonsymmetrical biaryl amines in excellent yields with high selectivities. This reaction provides a mild, operationally simple, and efficient approach for the synthesis of biaryls which are important to pharmaceutical and materials chemistry. A jab-cross move: A heterogeneously catalyzed oxidative dehydrogenative cross-coupling of aryl amines is reported. Aryl amines were treated with various arenes using a heterogeneous Rh/C catalyst under mild aerobic conditions to selectively afford cross-coupled products, and provides an efficient synthetic method for the preparation of nonsymmetrical biaryl amines by oxidative C-H activation.
- Matsumoto, Kenji,Yoshida, Masahiro,Shindo, Mitsuru
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supporting information
p. 5272 - 5276
(2016/04/26)
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- 6π/10π-Electrocyclization of ketene-iminium salts for the synthesis of substituted naphthylamines
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An intramolecular 6π/10π-electrocyclization from ketene-iminium salts was developed for the preparation of naphthylamines. Various substituents on the nitrogen, on the aromatic ring, and on the olefin were studied. Tricyclic skeletons were obtained in few steps and good overall yields. The electrocyclization of ketene-iminium salts has been computationally explored by means of DFT calculations and their activation barriers were compared to the parent triene as well as the corresponding dienyl allenes and dienyl ketenes. Electrocyclizations for ketene-iminium salts were shown to be highly exergonic and have much smaller barriers to activation.
- Villedieu-Percheron, Emmanuelle,Catak, Saron,Zurwerra, Didier,Staiger, Roman,Lachia, Mathilde,De Mesmaeker, Alain
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p. 2446 - 2449
(2014/05/06)
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- Hyperaromatic stabilization of arenium ions: Acid-catalyzed dehydration of 2-substituted 1,2-dihydro-1-naphthols
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Rate constants for acid-catalyzed dehydration of cis-2-substituted 1,2-dihydro-naphthols are well correlated by the Taft relationship log k = -0.49 - 8.8σI, with minor negative deviations for OH and OMe. By contrast the trans substituents show a poor correlation with σI and in most cases react more slowly than their cis isomers. The behavior is consistent with rate-determining formation of a 2-substituted carbocation (naphthalenium ion) intermediate that for cis reactants possesses a 2-C-H bond suitably oriented for hyperconjugation with the charge center. For the trans isomers the 2-substituent itself is oriented for hyperconjugation in the initially formed conformation of the cation. It is argued that k cis/ktrans rate ratios for substituents (Me, 8.4; Bu t, 12.7; Ph, 3.8; NH3+, 160; OH, 440) reflect their hyperconjugating ability relative to hydrogen. Faster reactions of trans isomers are observed for substitutents known (RS, N3) or suspected (EtSO, EtSO2) of stabilizing the cation by a π or σ neighboring group effect. The good Taft correlation is taken to indicate that cis substuents are reacting normally, differentiated only by their inductive effects. The slower reactions of the trans isomers are the judged to be "abnormal". This is confirmed by comparing effects of cis and trans β-OH substituents on the reactivities of dihydro phenols, naphthols, and phenanthrols. Whereas kH/kOH for cis substituents varies by less than 8-fold and is consistent with the influence of an inductive effect of the OH group (kH/kOH ≈ 2000), kH/k OH for the trans substituents varies by 3 orders of magnitude, reflecting the additional influence of the lesser hyperconjugating ability of a C-OH bond compared to a C-H bond. The magnitude and variation of this difference is consistent with C-H hyperconjugation conferring aromatic character on the arenium ions
- Kudavalli, Jaya Satyanarayana,Coyne, Dara,O'Ferrall, Rory A. More
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p. 563 - 572
(2012/03/26)
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- Benzannulation from alkyne without metallic catalysts at room temperature to 100 °C
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(Figure presented) An efficient, novel metal-catalyst-free aminobenzannulation of 2-(prop-2-ynyl)(oxo)benzenes 1 with various dialkylamlnes 2 afforded a variety of 2-aminonaphthalenes 3 in good to excellent yields under mild reaction conditions at room temperature to 100 °C (at most).
- Jin, Tienan,Yang, Fan,Yamamoto, Yoshinori
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supporting information; experimental part
p. 388 - 390
(2010/03/04)
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- A simple and effective procedure for the N-permethylation of amino-substituted naphthalenes
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A wide range of amino-substituted naphthalenes can be N-permethylated by the system Me2SO4/Na2CO3/ H2O(alcohols) with good to excellent yields. Steric hindrance does not prevent the reaction. Some amines with electron-withdrawing groups, especially at nonconjugated positions, are also alkylated. The procedure allows the combination of a reduction (catalytic or by tin dichloride in acidic media) and a methylation in a one-pot process. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Sorokin, Vladimir I.,Ozeryanskii, Valery A.,Pozharskii, Alexander F.
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p. 496 - 498
(2007/10/03)
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- Synthesis of aminonaphthalene derivatives using the bucherer reaction under microwave irradiation
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A very simple and efficient method to prepare aminonaphthalene derivatives in good yield using the Bucherer reaction under microwave irradiation in a closed vessel is described. A reaction time of 30 min at 150 Watts of microwave power was established as the optimum irradiation conditions when approximately 2 g of the initial hydroxynaphthalene was used in the synthesis.
- Canete,Melendrez,Saitz,Zanocco
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p. 2143 - 2148
(2007/10/03)
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- Heterocyclic amide derivatives
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Novel heterocyclic amide derivatives of the formula STR1 in which R1 represents alkyl, or represents alkenyl which has more than 2 carbon atoms and is optionally substituted by halogen, or represents alkinyl which has more than 2 carbon atoms and is optionally substituted by halogen, or represents alkoxyalkyl or alkylthioalkyl; R2 represents optionally substituted naphthyl, or represents optionally substituted tetrahydronaphthyl, or represents optionally substituted indanyl; A represents an alkylene bridge, or also an alkenylene bridge if X denotes a direct bond; X represents oxygen, sulphur or a direct bond; Y represents oxygen or sulphur; B represents imidazol-1-yl, pyridin-3-yl, pyrazin-2-yl, pyrimidin-5-yl, 1,2,4-triazol-1-yl or 1-methyl-imidazol-5-yl-; and their acid addition salts and metal salt complexes, are outstandingly active as fungicides.
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