- 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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supporting information
p. 5022 - 5037
(2021/05/04)
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- N -Arylation of (hetero)arylamines using aryl sulfamates and carbamates via C-O bond activation enabled by a reusable and durable nickel(0) catalyst
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An effective and general aryl amination protocol has been developed using a magnetically recoverable Ni(0) based nanocatalyst. This new stable catalyst was prepared on Fe3O4@SiO2 modified by EDTA and investigated by FT-IR, EDX, TEM, XRD, DLS, FE-SEM, XPS, NMR, TGA, VSM, ICP and elemental analysis techniques. The reaction proceeded via carbon-oxygen bond cleavage of (hetero)aryl carbamates and sulfamates under simple and mild conditions without the use of any external ligands. This method demonstrated functional group tolerance in the N-arylation of various nitrogen-containing compounds as well as aliphatic amines, anilines, pyrroles, pyrazoles, imidazoles, indoles, and indazoles with good to excellent yields. Furthermore, the catalyst could be easily recovered by using an external magnetic field and directly reused at least six times without notable reduction in its activity. This journal is
- Dindarloo Inaloo, Iman,Majnooni, Sahar,Eslahi, Hassan,Esmaeilpour, Mohsen
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p. 13266 - 13278
(2020/10/07)
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- Experimental and computational study of the 1,5-o → n carbamoyl snieckus-fries-type rearrangement
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The reactions of o-lithiated O-aryl N,N-diethylcarbamates with different C-N multiple bond electrophiles have been thoroughly studied. A 1,5-O → N carbamoyl shift, a new variation of the anionic Fries-type rearrangement, takes place when nitriles, imines, or alkylcarbodiimides are employed. In these cases, the carbamoyl group plays a dual role as a directing group, building up a variety of functional groups through the 1,5-O → N carbamoyl migration. On the other hand, the use of iso(thio)cyanates and arylcarbodiimides led to non-rearranged o-functionalized Oarylcarbamates. This reactivity was further computationally explored, and the governing factor could be traced back to the relative basicity of the alternative products (migrated vs nonmigrated substrates). This exploration also provided interesting insights about the degree of complexation of the lithium cations onto these substrates. A new access to useful 2-hydroxybenzophenone derivatives has also been developed.
- Feberero, Claudia,Lopez, Carlos Silva,Sanz, Roberto,Sedano, Carlos,Suarez-Pantiga, Samuel
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p. 12561 - 12578
(2020/11/09)
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- Aryl Carbamates: Mechanisms of Orthosodiations and Snieckus-Fries Rearrangements
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Aryl carbamates are orthometalated by sodium diisopropylamide (NaDA) in tetrahydrofuran. The resulting arylsodiums undergo Snieckus-Fries rearrangement to give orthoacylated phenols in good yield. The intermediate arylsodiums and resulting orthoacylated phenolates are suggested to be monomeric. The rate-limiting step in the two-step sequence depends on the steric demands of the carbamoyl moiety and the substituents in the meta position of the arene. Rate studies reveal a dominant disolvated-monomer-based orthometalation followed by a di- or trisolvated arylsodium monomer-based rearrangement. Kinetic evidence of a NaDA-catalyzed Snieckus-Fries rearrangement suggests the intermediacy of mixed trimers. Competitive halide eliminations to form benzyne are also discussed.
- Ma, Yun,Woltornist, Ryan A.,Algera, Russell F.,Collum, David B.
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supporting information
p. 9051 - 9057
(2019/08/15)
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- Aerobic C(sp2)-H Hydroxylations of 2-Aryloxazolines: Fast Access to Excited-State Intramolecular Proton Transfer (ESIPT)-Based Luminophores
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The direct hydroxylation of 2-aryloxazolines via a deprotonative magnesiation using TMPMgCl·LiCl and subsequent oxidation with molecular oxygen or air as a green oxidant is reported. This method proceeds under mild conditions at room temperature with high regioselectivity and chemoselectivity. The obtained phenols exhibit tunable luminescence properties, induced by excited-state intramolecular proton transfer. This method opens a new opportunity for the sustainable synthesis of luminescent organic molecules.
- G?bel, Dominik,Clamor, Nils,Lork, Enno,Nachtsheim, Boris J.
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supporting information
p. 5373 - 5377
(2019/06/07)
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- Access to Biphenyls by Palladium-Catalyzed Oxidative Coupling of Phenyl Carbamates and Phenols
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The oxidative cross-coupling of phenols (3 equiv) to various substituted phenyl N, N -diethylcarbamates was explored with a variety of substrates. Pd(OAc) 2 was employed as the catalyst (20 molpercent) and K 2 S 2 O 8
- Bach, Thorsten,Breitenlechner, Stefan,Jandl, Christian,P?thig, Alexander,Truchan, Nadina
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p. 3060 - 3076
(2019/08/07)
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- Directed ortho-Metalation of O-Aryl N,N-Dialkylcarbamates: Methodology, Anionic ortho-Fries Rearrangement, and Lateral Metalation
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The directed ortho-lithiation reactions of O-aryl N,N-dialkylcarbamates as well as O-1-naphthyl and O-2-naphthyl N,N-dialkylcarbamates with sec-butyllithium/tetramethylethylenediamine (sBuLi/TMEDA) followed by quenching with various electrophiles afford a range of polysubstituted aromatic compounds. If the solutions of the ortho-lithiated carbamates are warmed to room temperature without the addition of external electrophiles, salicylamide and 1- and 2-hydroxynaphthamide derivatives are formed through anionic ortho-Fries rearrangements. The relative stabilities and reactivities of different O-aryl N,N-dialkylcarbamates were investigated. The lateral metalation of 2-tolyl carbamates with lithium diisopropylamide (LDA) provides a route to benzo[b]furan-2(3H)-ones. Previously reported results are used in a comparison of seven O-based directed metalation groups in reactions with several electrophiles. The described methodology is useful for the preparation of 1,2,3-substituted aromatic compounds.
- Miah, M. A. Jalil,Sibi, Mukund P.,Chattopadhyay,Familoni, Oluwole B.,Snieckus, Victor
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supporting information
p. 440 - 446
(2017/12/15)
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- 1,5-O → N Carbamoyl Snieckus-Fries-Type Rearrangement
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The reaction of o-lithiated O-aryl N,N-diethylcarbamates with (hetero)aromatic nitriles gives rise to functionalized salicylidene urea derivatives in high yields through a new 1,5-O → N carbamoyl migration. This Snieckus-Fries-type rearrangement nicely complements previously known O → C and O → O related shifts. In addition, when dimethylmalononitrile is used as the electrophilic partner, the carbamoyl shift is preferred over the expected transnitrilation reaction.
- Feberero, Claudia,Suárez-Pantiga, Samuel,Cabello, Zaida,Sanz, Roberto
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supporting information
p. 2437 - 2440
(2018/04/27)
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- A copper-catalyzed oxidative coupling reaction of arylboronic acids, amines and carbon dioxide using molecular oxygen as the oxidant
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A Cu-catalyzed oxidative coupling reaction of arylboronic acids, amines and carbon dioxide is described for the first time in this paper. The reaction tolerates a wide range of functional groups, providing a convenient protocol for the synthesis of various O-aryl carbamates. The successful development of the transformation was enabled by the use of BF3·OEt2 as the promoter and molecular oxygen as the oxidant. Mechanistic studies suggested that the CuII carbamato complex is involved in the catalytic transformation.
- Xiong, Wenfang,Qi, Chaorong,Guo, Tianzuo,Zhang, Min,Chen, Kai,Jiang, Huanfeng
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p. 1642 - 1645
(2017/06/05)
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- Nickel-catalyzed C?H arylation of benzoxazoles and oxazoles: Benchmarking the influence of electronic, steric and leaving group variations in phenolic electrophiles
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Electronic, steric and leaving group effects for Ni-catalyzed direct arylations using C?O electrophiles were benchmarked. The scope of arylations with pivalates was general with respect to both the electronics on the electrophile and the azoles. Furthermore, the arylation of azoles with tosylates, mesylates and carbamates with varying electronics was explored, and showed electronic trends similar to those of the pivalate reactions. Finally, the relative rate of arylation of 5-methyl benzoxazole with two electronically-similar electrophiles bearing different leaving groups was established. The results from these studies implicate the following order of relative reactivity: mesylates>pivalates>carbamates.
- Steinberg, Deborah F.,Turk, Morgan C.,Kalyani, Dipannita
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p. 2196 - 2209
(2017/03/24)
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- A facile synthesis of sulfonylureas: Via water assisted preparation of carbamates
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A novel and simple approach to the synthesis of sulfonylureas has been reported. It involved the reaction of various amines with diphenyl carbonate to yield the corresponding carbamates, which subsequently reacted with different sulphonamides to produce different sulfonylureas in excellent yields. The first reaction of diphenyl carbonate with amines was carried out in aqueous:organic (H2O:THF, 90:10) medium at room temperature to produce carbamates that paved a straightforward route to sulfonylureas after reaction with sulfonamides. The above process avoided traditional multistep protocols and the use of hazardous, irritant, toxic and moisture sensitive reagents such as phosgene, isocyanates and/or chloroformates.
- Tanwar, Dinesh Kumar,Ratan, Anjali,Gill, Manjinder Singh
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p. 4992 - 4999
(2017/07/11)
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- A method of synthesizing aromatic carbamate
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The invention relates to a synthetic method for romatic carbamic acid ester. The method comprises the following steps: adding diaryliodonium salt, amine, alkali and an organic solvent into a high-pressure reaction kettle, wherein diaryliodonium salt and a
- -
-
Paragraph 0096-0097
(2018/02/04)
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- Base-Promoted Coupling of Carbon Dioxide, Amines, and Diaryliodonium Salts: A Phosgene- and Metal-Free Route to O-Aryl Carbamates
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A phosgene- and metal-free synthesis of O-aryl carbamates is realized through a three-component coupling of carbon dioxide, amines and diaryliodonium salts. The reaction only requires a base as the promoter, providing access to a diverse array of O-aryl c
- Xiong, Wenfang,Qi, Chaorong,Peng, Youbin,Guo, Tianzuo,Zhang, Min,Jiang, Huanfeng
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supporting information
p. 14314 - 14318
(2015/10/05)
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- Ligand-assisted copper-catalyzed oxidative cross-coupling of simple phenols with formamides for the synthesis of carbamates
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An oxidative approach for the synthesis of phenyl carbamates has been achieved by ligand-assisted copper-catalyzed cross-dehydrogenative coupling (CDC) of phenols with formamides. The direct coupling of simple phenols with mono- and dialkyl formamides pro
- Reddy, Nagireddy Veera,Kumar, Gadde Sathish,Kumar, Pailla Santhosh,Kantam, M. Lakshmi,Reddy, Kallu Rajender
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supporting information
p. 2133 - 2138
(2014/11/08)
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- Lithiation of a silyl ether: Formation of an ortho-fries hydroxyketone
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A hydroxy-directed alkylation of an N,N-diethylarylamide using CIPE-assisted α-silyl carbanions (CIPE=complex-induced proximity effect) has been developed using a simple reagent combination of LDA (lithium diisopropylamide) and chlorosilane. A study of the mechanism, and the application of the procedure to an anionic Snieckus-Fries rearrangement for a highly efficient synthesis of the potent phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002, are reported.
- Lo, Hong-Jay,Lin, Chin-Yin,Tseng, Mei-Chun,Chein, Rong-Jie
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supporting information
p. 9026 - 9029
(2014/09/17)
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- Suzuki-Miyaura coupling of aryl carbamates, carbonates, and sulfamates
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(Chemical Equation Presented) The first Suzuki-Miyaura cross-couplings of carbamates, carbonates, and sulfamates is described. The method provides a powerful means of using simple derivatives of phenol as precursors to polysubstituted aromatic compounds, as exemplified by a concise synthesis of the anti-inflammatory drug flurbiprofen.
- Quasdorf, Kyle W.,Riener, Michelle,Petrova, Krastina V.,Garg, Neil K.
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supporting information; experimental part
p. 17748 - 17749
(2010/04/01)
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- Anionic ortho-fries rearrangement, a facile route to arenol-based mannich bases
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Phenol and 1-naphthol-based carbamates undergo the anionic ortho-Fries rearrangement to their corresponding amides. Bulky substitution at position 8 of 1-naphthol-based carbamates makes the rearrangement an exclusive reaction, even at -90 C, under a variety of conditions. The amides can be efficiently reduced to the corresponding Mannich bases. A novel route to 7-[(dialkylamino)methyl]-8- hydroxy-1-naphthaldehydes is presented.
- Assimomytis, Nikos,Sariyannis, Yiannis,Stavropoulos, Georgios,Tsoungas, Petros G.,Varvounis, George,Cordopatis, Paul
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scheme or table
p. 2777 - 2782
(2010/03/03)
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- Tandem multi-step synthesis of C-carboxyazlactones promoted by N-heterocyclic carbenes
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Cascade reaction sequences incorporating N-heterocyclic carbene-based organocatalysis have been developed that allow the direct preparation of a range of (±)-4-phenoxycarbonylazlactones in good isolated yields (66-84%) from the corresponding N-p-anisoyl amino acids. The Royal Society of Chemistry.
- Campbell, Craig D.,Duguet, Nicolas,Gallagher, Katherine A.,Thomson, Jennifer E.,Lindsay, Anita G.,O'Donoghue, AnnMarie C.,Smith, Andrew D.
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supporting information; body text
p. 3528 - 3530
(2009/02/05)
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- Suppressing the anionic fries rearrangement of aryl dialkylcarbamates; the isolation of a crystalline ortho-deprotonated carbamate
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In the presence of organolithium bases phenyl dialkylcarbamates have previously been shown to undergo facile rearrangement to yield the corresponding salicylamides. However, heterometallic lithium diethyl(2,2,6,6- tetramethylpiperidido)zincate achieves th
- Garcia, Felipe,McPartlin, Mary,Morey, James V.,Nobuto, Daisuke,Kondo, Yoshinori,Naka, Hiroshi,Uchiyama, Masanobu,Wheatley, Andrew E. H.
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p. 644 - 647
(2008/09/17)
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- Strategies towards the synthesis of 6-N,N-diethylcarbamyloxy-1,4-dimethoxy- 7-naphthylboronic acid
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After acetylation, condensation between Danishefsky's diene and benzoquinone afforded a stable methoxytriacetoxydihydronaphthalene intermediate, which was subsequently transformed by the Snieckus DOM protocol into the regiospecific 7-naphthylboronic acid.
- Ameer,Green, Ivan R.,Krohn,Sitoza
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p. 3041 - 3057
(2008/02/12)
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- Application of directed metalation in synthesis. Part 6: A novel anionic rearrangement under directed metalation conditions leading to heteroannulation
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A short and efficient synthesis of condensed 1,4-oxathiin-2-ones from easily available phenols is described. The key step in this synthesis is a hitherto unreported anionic rearrangement under directed metalation conditions. The rearrangement occurs after
- Pradhan, Tarun Kanti,Mukherjee, Chandrani,Kamila, Sukanta,De, Asish
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p. 5215 - 5224
(2007/10/03)
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- Application of directed orthometalation toward the synthesis of aryl siloxanes
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A selection of ortho-substituted aryl siloxanes have been prepared by directed orthometalation protocols. These siloxanes can be prepared in high yields and purity by use of a diverse selection of ortho-directing groups and electrophilic siloxane derivatives. The siloxanes are employed in palladium-catalyzed cross-coupling reactions with aryl bromides to generate unsymmetrical orthosubstituted biaryls in good to excellent yields.
- Seganish, W. Michael,DeShong, Philip
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p. 6790 - 6795
(2007/10/03)
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- Application of directed metalation in synthesis. Part 5:1,2 Synthesis of condensed sulfur-oxygen heterocycle via novel anionic rearrangement-cyclisation
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Introduction of the methyl sulfanyl function in the ortho-position to O-carbamate functionality under standard directed metalation condition was followed by side-chain deprotonation with sec-butyl lithium at -78 °C. Upon warming to room temperature, the d
- Mukherjee, Chandrani,Kamila, Sukanta,De, Asish
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p. 1474 - 1478
(2007/10/03)
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- Phenyl chloro(thionoformate): A new dealkylating agent of tertiary amines
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Phenyl chloro(thionoformate) reacts rapidly with unhindered tertiary aliphatic amines at 20° to give a thiocarbamate and an alkyl chloride. Dialkylcyclohexylamines react surprisingly rapidly to form predominantly cyclohexene. The thiocarbamates are converted into the secondary amine salt by treatment with dimethyl sulfate, followed by hydrolysis with water. Rates of reaction and alkyl group cleavage selectivity in amines were found to be superior or comparable to those previously reported with chloroformates.
- Milan, David S.,Prager, Rolf H.
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p. 841 - 849
(2007/10/03)
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- Contra-thermodynamic trans-esteripication of carbamates by counter-attack strategy: A viable non-phosgene, non-mic route to carbamate pesticides
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Treatment of methyl N-methylcarbaaate (1, R= Me) with phosphorus oxychloride and 1-naphthol results in the formation of the transesterified product, 1-naphthyl N-methylcarbamate (2, Ar=1-naphthy 1) in good yield. Similarly, ethyl N-methylthiocarbamate (5) is converted to 1-naphthyl N-methylcarbamate (2, Ar= 1-naphthyl) on treatment with phosphorus oxychloride and 1-naphthol. The mechanism of these interesting and industrially important transformations is discussed.
- Kulkarni,Naik,Tandel,Rajappa
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p. 1249 - 1256
(2007/10/02)
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- α-Haloalkyl Haloformates and Related Compounds 1. A Convenient Synthesis of Carbamates via Chloromethyl Carbamates
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The preparation of carbamates under mild conditions utilizing a new class of activated carbonates (containing chloromethyl function) is described.
- Patonay, Tamas,Patonay-Peli, Erzsebet,Mogyorodi, Ferenc
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p. 2865 - 2885
(2007/10/02)
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- Silicon Polonovski Reaction. Formation and Synthetic Application of α-Siloxy Amines
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A new and versatile synthetic intermediate, α-siloxy amine was prepared in situ by the base-promoted rearrangement of a siloxyammonium salt obtained by treatment of a tertiary amine N-oxide with trialkylsilyl trifluoromethanesulfonate.The best combination of the base and silylating reagent was found to be methyllithium and t-butyldimethylsilyl trifluoromethanesulfonate.The reactions of α-siloxy amines with acyl halides and haloformates gave the corresponding amides and carbamates in moderate to good yields, respectively.Treatment of α-siloxy amines with acetic acid resulted in a direct dealkylation to free secondary amines.Fluoride induced alkylation of α-siloxy amines using alkyl halides as electrophiles leading to tertiary amines was also examined and demonstrated to be a new transalkylation method of amines.
- Tokitoh, Norihiro,Okazaki, Renji
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p. 3291 - 3298
(2007/10/02)
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- REACTION OF PHENOL WITH DIETHYLCARBAMOYL CHLORIDE IN THE PRESENCE OF LEWIS ACID
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In the presence of either SnCl4 or AlCl3, phenol reacts with diethylcarbamoyl chloride to give phenyl N,N-diethylcarbamate, which undergoes the Fries rearrangement at 170-180 deg C and is capable of being acylated by diethylcarbamoyl chloride in the para position.
- Isakova, A. P.,Naumov, Yu. A.,Nikeryasova, S. V.,Stepanova, A. A.
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p. 1115 - 1119
(2007/10/02)
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