- MeOTf-catalyzed formal [4?+?2] annulations of styrene oxides with alkynes leading to polysubstituted naphthalenes through sequential electrophilic cyclization/ring expansion
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MeOTf-catalyzed formal [4 + 2] annulation of styrene oxides with alkynes to afford polysubstituted naphthalenes has been realized, which undergoes sequential electrophilic cyclization/ring expansion. A range of substrates were tolerated in the formation of naphthalene derivatives with high regioselectivity in satisfactory yields. The reaction could also be carried out on gram scale.
- Chen, Chao,Xi, Chanjuan,Zhang, Zeyu,Zou, Song
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supporting information
(2021/12/30)
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- C(sp2)-C(sp2) Suzuki cross-coupling of arylammonium salts catalyzed by a stable Pd–NHC complex
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We have developed the Suzuki-Miyaura cross-coupling of aryl ammonium salts via C–N bond activation catalyzed by an easily prepared and bench-stable palladium-N-heterocyclic carbene complex. The reaction proceeded well under mild conditions with phenylboronic acid, pinacol ester or anhydride and provided yields of products up to 97% with good functional group compatibility. The direct arylation of arylamine can be performed by a two-step one-pot process and the protocol can be performed on the gram scale.
- Tang, Huiling,Liu, Mengna,Zhu, Meiqi,Cui, Benqiang,Shi, Yanhui,Cao, Changsheng
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- Pd/NHC-catalyzed cross-coupling reactions of nitroarenes
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N-Heterocyclic carbene (NHC) ligands effective for the cross-coupling of nitroarenes were identified. A rational design of the NHC ligand structures enabled significant reduction of catalyst loadings compared with the previous system employing BrettPhos as a phosphine ligand. Experimental and theoretical studies to compare these ligands gave some insights into high activity of the newly developed NHC ligands.
- Kashihara, Myuto,Zhong, Rong-Lin,Semba, Kazuhiko,Sakaki, Shigeyoshi,Nakao, Yoshiaki
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supporting information
p. 9291 - 9294
(2019/08/08)
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- Sterically hindered N-heterocyclic carbene/palladium(ii) catalyzed Suzuki-Miyaura coupling of nitrobenzenes
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Palladium-catalyzed denitrative Suzuki coupling of nitroarenes using 2-aryl-5-(2,4,6-triisopropylphenyl)-2,3-imidazolylidene[1,5-a]pyridines as the ligands is described. The key to success is the use of the NHC ligands which show strong donating ability and suitable steric hindrance allowing the successful oxidative addition of Ar-NO2 bonds. Both aromatic and aliphatic boronic acids are tolerated, and a variety of biphenyls and alkylarenes were obtained in good to excellent yields.
- Chen, Kai,Chen, Wei,Yi, Xiaofei,Chen, Wanzhi,Liu, Miaochang,Wu, Huayue
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supporting information
p. 9287 - 9290
(2019/08/08)
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- Nickel-Catalyzed Stille Cross Coupling of C-O Electrophiles
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Aryl sulfamates, tosylates, and mesylates undergo efficient Ni-catalyzed cross coupling with diverse organostannanes in the presence of relatively unhindered alkylphosphine ligands and KF. The coupling is valuable for difficult bond constructions, such as aryl - heteroaryl, aryl - alkenyl, and aryl - alkynyl, using nontriflate phenol derivatives. A combination of experimental and computational studies implicates an unusual mechanism for transmetalation involving an 8-centered cyclic transition state. This reaction is inhibited by chloride sources due to slow transmetalation of organostannanes at a Ni(II) - chloride intermediate. These studies help to explain why prior efforts to achieve Ni-catalyzed Stille coupling of phenol derivatives were unsuccessful.
- Russell, John E. A.,Entz, Emily D.,Joyce, Ian M.,Neufeldt, Sharon R.
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p. 3304 - 3310
(2019/03/26)
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- Nickel-Catalyzed Csp2-Csp3 Bond Formation via C-F Bond Activation
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A nickel-catalyzed cross coupling of aryl fluorides via C-F bond activation has been developed. The alkylation method allows selective replacement of aryl fluorides by alkyl groups and enables the synthesis of diverse and otherwise difficult to access scaffolds in good yields.
- Ho, Yee Ann,Leiendecker, Matthias,Liu, Xiangqian,Wang, Chengming,Alandini, Nurtalya,Rueping, Magnus
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supporting information
p. 5644 - 5647
(2018/09/12)
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- Iron-catalyzed coupling of aryl sulfamates and aryl/vinyl tosylates with aryl grignards
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The iron-catalyzed coupling of aryl sulfamates and tosylates with aryl Grignard reagents is reported for the first time. The methodology employs air-stable, low-cost FeF3·3H2O and the N-heterocyclic carbene ligand IPr·HCl as the preligand to form a long-lived catalyst upon treatment with aryl Grignards. The reaction provides a range of cross-coupled products in good-to-excellent yields. In contrast to previous reports with aryl chlorides, these reactions proceed with low levels of Grignard homocoupling regardless of the iron source.
- Agrawal, Toolika,Cook, Silas P.
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supporting information
p. 5080 - 5083
(2014/12/11)
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- Palladium-catalyzed Suzuki-Miyaura coupling of aryl sulfamates with arylboronic acids
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Readily available NHC-Pd(ii)-Mp complexes 2 showed efficient catalytic activity toward the Suzuki-Miyaura coupling of aryl sulfamates with arylboronic acids or potassium phenyltrifluoroborate, giving the expected coupling products in good to high yields.
- Wang, Zhan-Yong,Ma, Qin-Na,Li, Ren-Hao,Shao, Li-Xiong
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p. 7899 - 7906
(2013/11/19)
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- Synthesis of naphthalene derivatives through inexpensive BF 3·Et2O-catalyzed annulation reaction of arylacetaldehydes with arylalkynes
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An inexpensive BF3·Et2O-catalyzed annulation reaction of arylacetaldehydes with arylalkynes has been developed. Various substituted phenylacetaldehydes and phenylacetylenes can undergo this reaction, producing corresponding α-aryl su
- Xiang, Shikai,Hu, Hao,Ma, Jing,Li, Yuanzhuo,Wang, Biqin,Feng, Chun,Zhao, Keqing,Hu, Ping,Chen, Xiaozhen
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p. 945 - 951
(2013/08/23)
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- Base- and metal-free C-H direct arylations of naphthalene and other unbiased arenes with diaryliodonium salts
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A novel metal-free direct arylation of unbiased arenes with diaryliodonium triflates in a process where the use of solvents and additives is not required has been established.
- Castro, Susana,Fernandez, Juan J.,Vicente, Ruben,Fananas, Francisco J.,Rodriguez, Felix
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supporting information
p. 9089 - 9091
(2012/11/07)
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- N-heterocyclic carbene-palladium(II)-1-methylimidazole complex-catalyzed Suzuki-Miyaura coupling of aryl sulfonates with arylboronic acids
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A well-defined NHC-Pd(II)-Im complex 1 was found to be an effective catalyst for the Suzuki-Miyaura coupling of aryl sulfonates including tosylates and phenylsulfonates with arylboronic acids, giving the desired coupling products in good to high yields. Acceptable yields can also be achieved even by using the less reactive mesylates as the substrates. It is worthy of noting here that this is the first example of NHC-Pd(II) complex-catalyzed Suzuki-Miyaura coupling of aryl sulfonates with arylboronic acids, enriching an inexpensive, convenient, and alternative method for the synthesis of biaryl compounds.
- Wang, Zhan-Yong,Chen, Gao-Qi,Shao, Li-Xiong
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experimental part
p. 6608 - 6614
(2012/10/07)
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- Suzuki-Miyaura cross-coupling of aryl carbamates and sulfamates: Experimental and computational studies
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The first Suzuki-Miyaura cross-coupling reactions of the synthetically versatile aryl O-carbamate and O-sulfamate groups are described. The transformations utilize the inexpensive, bench-stable catalyst NiCl 2(PCy3)2 to furnish biaryls in good to excellent yields. A broad scope for this methodology has been demonstrated. Substrates with electron-donating and electron-withdrawing groups are tolerated, in addition to those that possess ortho substituents. Furthermore, heteroaryl substrates may be employed as coupling partners. A computational study providing the full catalytic cycles for these cross-coupling reactions is described. The oxidative addition with carbamates or sulfamates occurs via a five-centered transition state, resulting in the exclusive cleavage of the aryl C-O bond. Water is found to stabilize the Ni-carbamate catalyst resting state, which thus provides rationalization of the relative decreased rate of coupling of carbamates. Several synthetic applications are presented to showcase the utility of the methodology in the synthesis of polysubstituted aromatic compounds of natural product and bioactive molecule interest.
- Quasdorf, Kyle W.,Antoft-Finch, Aurora,Liu, Peng,Silberstein, Amanda L.,Komaromi, Anna,Blackburn, Tom,Ramgren, Stephen D.,Houk,Snieckus, Victor,Garg, Neil K.
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supporting information; experimental part
p. 6352 - 6363
(2011/06/19)
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- Nickel-catalyzed C-O activation of phenol derivatives with potassium heteroaryltrifluoroborates
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A general method based on nickel-catalyzed C-O activation of various phenol derivatives with potassium (hetero)aryltrifluoroborates has been developed. A large number of heterobiaryls can be easily obtained with yields up to 99% using methanesulfonate cross-coupling partners.
- Molander, Gary A.,Beaumard, Floriane
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supporting information; experimental part
p. 4022 - 4025
(2010/11/05)
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- Shape-dependent catalytic activity of copper oxide-supported Pd(0) nanoparticles for Suzuki and cyanation reactions
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Palladium nanoparticles supported on different shapes of nanocrystalline CuO are prepared by the treatment of Cu(NO3)2 and Pd(OAc)2 in polyethylene glycol (PEG-6000). The shapes of the CuO/Pd composite are dependent on the amount of PEG used. Suzuki coupling was catalyzed efficiently by the oval-shaped material, whereas the rod shape facilitates the cyanation reaction. The CuO/Pd catalyst is recovered and reused for subsequent Suzuki reactions; however, cyanation poisons the catalyst for further use. Both these reactions are very clean and high yielding.
- Chattopadhyay, Kalicharan,Dey, Raju,Ranu, Brindaban C.
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supporting information; experimental part
p. 3164 - 3167
(2009/08/09)
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- Synthesis of substituted naphthalenes via a catalytic ring-expansion rearrangement
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(Figure Presented) A new methodology for the preparation of substituted naphthalenes starting from readily available indenones, organometal reagents, and trimethylsilyldiazomethane via a catalytic rearrangement process is described. Hindered biaryl naphthalenes, including triortho-substituted biaryls, can be accessed through our method. Our results are consistent with a mechanism involving a benzobenzvalene intermediate.
- Glass, Adam C.,Morris, Benjamin B.,Zakharov, Lev N.,Liu, Shih-Yuan
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supporting information; experimental part
p. 4855 - 4857
(2009/05/31)
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- Hydrophilic CNC-pincer palladium complexes: A source for highly efficient, recyclable homogeneous catalysts in Suzuki-Miyaura cross-coupling
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The Suzuki biaryl coupling of a range of electronically dissimilar arylboronic acids and aryl bromides is performed in neat water with excellent to quantitative yields by means of a new CNC-pincer palladium catalyst that is soluble in water due to its para-carboxy group. Extremely high turn-over numbers and frequencies combined with a remarkable robustness allow an effective catalyst reuse in sustainable conditions.
- Churruca, Fatima,SanMartin, Raul,Ines, Blanca,Tellitu, Imanol,Dominguez, Esther
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p. 1836 - 1840
(2007/10/03)
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- Palladium-Catalyzed Stille Cross-Couplings of Sulfonyl Chlorides and Organostannanes
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Arene and phenylmethanesulfonyl chlorides can be cross-coupled with aryl, heteroaryl, and alkenylstannanes with desulfitation in the presence of 10 mol % CuBr·Me2S, 1.5 mol % Pd2dba3, and 5 mol % tri-2-furylphosphine in tetrahydrofuran or toluene under reflux. This extension of the Stille cross-coupling reaction realizes a new and economical method for the generation of C?C bonds. The palladium-catalyzed carbonylative Stille cross-coupling reactions of arenesulfonyl chlorides and organostannanes in the presence of CO (60 bar) at 110 °C in toluene generate the corresponding ketones. Arenesulfonyl chlorides are more reactive than aryl chlorides and aryl bromides in their Stille cross-coupling with organostannanes but less reactive than aryl iodides. The new methods disclosed for the generation of C?C bonds open new possibilities for medicinal chemistry and material sciences. Copyright
- Dubbaka, Srinivas Reddy,Vogel, Pierre
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p. 15292 - 15293
(2007/10/03)
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- Palladium-catalyzed cross-coupling reaction of triarylbismuths with aryl halides and triflates
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equation presented Palladium-catalyzed cross-coupling reaction of triarylbismuths with aryl bromides, iodides, and triflates proceeded efficiently in the presence of K2CO3 or CsF.
- Rao, Maddali L. N.,Yamazaki, Osamu,Shimada, Shigeru,Tanaka, Toshifumi,Suzuki, Yohichi,Tanaka, Masato
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p. 4103 - 4105
(2007/10/03)
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- Addition and Cyclization Reactions in the Thermal Conversion of Hydrocarbons with Enyne Structure, 3. - A Mechanistic Study of the Thermal Cycloisomerization of 1,4-Diphenyl-1-buten-3-yne
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The gas-phase pyrolysis of 1,4-diphenyl-1-buten-3-yne (1) was investigated in the temperature range between 600 and 800 deg C and in the presence of different carrier gases (N2, N2/toluene, H2).By a detailed analysis (GC, GC/MS, GC/FTIR) all volatile reaction products were identified and quantitatively determined.Besides several fragmentation products (substituted benzenes C7-C10) and some carbon-rich deposits the main products are benzene (4), naphthalene (5) as well as 1- (2) and 2-phenylnaphthalene (3).Under similar conditions 4-(4-fluorophenyl)-1-phenyl-1-buten-3-yne (1a) furnished mainly fluorobenzene (4a), naphthalene (5), 1- (2a) and 2-(4-fluorophenyl)naphthalene (3a). - If sufficient H atoms are available in the reactive gas phase the conversion of 1/1a is predominantly controlled by radical processes.The cycloisomerization of 1/1a presumably starts with previously formed vinyl radicals, which might initiate a multi-step reaction cascade involving a 1,x-H shift and homoallyl reactions.However, if the reaction system is poor in H atoms (or other chain carrier radicals), a cycloisomerization path via vinylidene carbene species and their subsequent stabilization by intramolecular 1,6-C,H insertion into 3/3a obviously dominates the reaction events.It is concluded that the 1,2-dihydro-2-phenyl-1-naphthyl radicals 19/19a and the 1,2-dihydro-1-phenyl-2-naphthyl radicals 21/21a are important intermediates which are not only precursors of the aromatics 2/2a and 3/3a but also thought to be key intermediates for the most important degradation products 4/4a and 5. - Key Words: Pyrolysis, gas-phase / Cycloisomerization / Vinyl radical / Vinylidene carbene / Rearrangement, homoallyl
- Hofmann, Joerg,Zimmermann, Gerhard,Homann, Klaus-Heinrich
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p. 841 - 848
(2007/10/02)
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- Characterization of a Longicyclic (2,2,2,2) Conjugated ? System in 1,4-Difluorobenzene-Naphthalene Biplanemer
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The electronic absorption of a 1,4-difluorobenzene-naphthalene biplanemer 1 exhibited a characteristic absorption band around 290 nm.This was attributable to intramolecular charge transfer interaction between the longicyclic conjugated ? system and the benzene chromophore.The oxidation potential of 1 was 1.70 V (vs.Ag/AgCl), which was lower than those of the related compounds in which one of the double bonds of 1 was hydrogenated.Thermally, the biplanemer 1 underwent facile Cope rearrangement, followed by dehydrofluorination, to give 1-(4-fluorophenyl)naphthalene and 2-(3-fluorophenyl)naphthalene.
- Okamoto, Hideki,Satake, Kyosuke,Kimura, Masaru
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p. 3557 - 3562
(2007/10/03)
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