- Inverting Conventional Chemoselectivity in the Sonogashira Coupling Reaction of Polyhalogenated Aryl Triflates with TMS-Arylalkynes
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A newly developed phosphine ligand with a C2-cyclohexyl group on the indole ring was successfully applied in a chemoselective Sonogashira coupling reaction with excellent chemoselectivity, affording an inversion of the conventional chemoselectivity order of C–Br > C–Cl > C–OTf. This study also provided an efficient approach to the synthesis of polycyclic aromatic hydrocarbons (PAHs) and the natural product analogue trimethyl-selaginellin L by merging of chemoselective Sonogashira and Suzuki–Miyaura coupling reactions.
- Wang, Miao,So, Chau Ming
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supporting information
p. 681 - 685
(2022/01/20)
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- N-Heterocyclic Carbene Ligand-Controlled Chemodivergent Suzuki-Miyaura Cross Coupling
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Two N-heterocyclic carbene ligands provide orthogonal chemoselectivity during the Pd-catalyzed Suzuki-Miyaura (SM) cross-coupling of chloroaryl triflates. The use of SIPr [SIPr = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene] leads to selective cross-coupling at chloride, while the use of SIMes [SIMes = 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene] provides selective coupling at triflate. With most chloroaryl triflates and arylboronic acids, ligand-controlled selectivity is high (≥10:1). The scope of this methodology is significantly more general than previously reported methods for selective SM coupling of chloroaryl triflates using phosphine ligands. Density functional theory studies suggest that palladium's ligation state during oxidative addition is different with SIMes compared to SIPr.
- Reeves, Emily K.,Humke, Jenna N.,Neufeldt, Sharon R.
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p. 11799 - 11812
(2019/10/11)
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- Modular Functionalization of Arenes in a Triply Selective Sequence: Rapid C(sp2) and C(sp3) Coupling of C?Br, C?OTf, and C?Cl Bonds Enabled by a Single Palladium(I) Dimer
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Full control over multiple competing coupling sites would enable straightforward access to densely functionalized compound libraries. Historically, the site selection in Pd0-catalyzed functionalizations of poly(pseudo)halogenated arenes has been unpredictable, being dependent on the employed catalyst, the reaction conditions, and the substrate itself. Building on our previous report of C?Br-selective functionalization in the presence of C?OTf and C?Cl bonds, we herein complete the sequence and demonstrate the first general arylations and alkylations of C?OTf bonds (in I dimer. This allowed the realization of the first general and triply selective sequential C?C coupling (in 2D and 3D space) of C?Br followed by C?OTf and then C?Cl bonds.
- Keaveney, Sinead T.,Kundu, Gourab,Schoenebeck, Franziska
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supporting information
p. 12573 - 12577
(2018/09/18)
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- Tandem thia-Fries rearrangement-cyclisation of 2-(trimethylsilyl)phenyl trifluoromethanesulfonate benzyne precursors
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A novel transformation of 2-(trimethylsilyl)phenyl trifluoromethanesulfonate aryne precursors is described. The Royal Society of Chemistry.
- Hall, Catherine,Henderson, Jaclyn L.,Ernouf, Guillaume,Greaney, Michael F.
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supporting information
p. 7602 - 7604
(2013/09/02)
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- Intermolecular mizoroki-heck reaction of aliphatic olefins with high selectivity for substitution at the internal position
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New ligand for old reaction: The title reaction of aryltriflates with aliphatic olefins leads to substitution at the internal position with high selectivity. The ratio of the desired isomer (shown in the scheme) to the sum of all other isomers is generall
- Qin, Liena,Ren, Xinfeng,Lu, Yunpeng,Li, Yongxin,Zhou, Jianrong
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supporting information; experimental part
p. 5915 - 5919
(2012/07/30)
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- Palladium-catalyzed desulfitative arylation by C-O bond cleavage of aryl triflates with sodium arylsulfinates
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An efficient Pd-catalyzed desulfitative coupling reaction of sodium arylsulfinates as arylation reagents by C-O bond cleavage of aryl triflates was developed. With only 2 mol % of Pd(OAc)2 as catalyst and XPhos as ligand, the reaction proceeded well for a range of substrates.
- Zhou, Chao,Liu, Qingjiang,Li, Yaming,Zhang, Rong,Fu, Xinmei,Duan, Chunying
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p. 10468 - 10472
(2013/01/15)
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- A novel approach to 3-methylindoles by a heck/cyclization/isomerization process
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Chemical Equation presented A novel synthesis of 3-methyllndoles from chlorotrlflates through a Heck reaction, carbamate/aryl chloride coupling, and Isomerlzatlon sequence Is presented. The three-step sequence Is highly efficient and general, enabling the
- Baxter, Carl A.,Cleator, Ed,Alam, Mahbub,Davies, Antony J.,Goodyear, Adrian,o'Hagan, Michael
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supporting information; experimental part
p. 668 - 671
(2010/04/02)
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- Synthesis of hydroxylated oligoarene-type phosphines by a repetitive two-step method
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Hydroxylated oligoarene-type phosphines with various substitution patterns were synthesized. Such phosphines have potential as ligands for transition metal-catalyzed reactions. A successful route, which includes a repetitive Suzuki-Miyaura coupling-triflation sequence, reduction, and salt formation, was established starting from 2-bromophenyldicyclohexylphosphine oxide. Other key aspects of the method are the use of suitable triflation reagents and the formation of phosphines as HBF4 salts. Interesting information was obtained from careful analysis of the byproducts in the triflation and reduction steps, and the mechanisms for their formation were proposed.
- Ishikawa, Shunpei,Manabe, Kei
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supporting information; experimental part
p. 297 - 303
(2010/03/24)
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- Low-Temperature Ag/Pd-catalyzed decarboxylative cross-coupling of aryl trflates with aromatic carboxylate salts
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Chemical Equation Presented At 50°C lower than the best known copper catalysts, a catalytic silver(I)/ palladium(II) system allows the decarboxylative cross-coupling of arenecarboxylates with aryl triflates at temper-atures as low as 120°C. Remarkably, polychlorinated and many heterocyclic arenecarboxylates are converted for the first time in high yields. FG = functional group.
- Goossen, Lukas J.,Lange, Paul P.,Rodriguez, Nuria,Linder, Christophe
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supporting information; experimental part
p. 3906 - 3909
(2010/07/03)
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- Modular synthesis of indoles from imines and o-dihaloarenes or o-chlorosulfonates by a Pd-catalyzed cascade process
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A detailed study of the scope of a new Pd-catalyzed synthesis of indolesfrom 1,2-dihaloarenes and o-halobenzene sulfonates and imines is descri bed. The cascade reaction comprises an imine a-arylation ollowed by an intramolecular C-N bond-forming reaction promoted by the same Pd catalyst. The reaction with 1,2-dibromobenzene shows wide scope and allows the introduction of aryl, alkyl, and vinyl substituents at different positions of the five-membered ring of the indole. The regioselective synthesis of indoles substituted in the six-membered ring can be carried out by employing o-dihalobenzene derivatives with two different halogens, taking advantage of the different reactivities of I, Br, and Cl in oxidative addition reactions. This paper also introduces a method for the efficient cleavage of the N-t-butyl group, thus allowing for the preparation of N-H indoles through the same methodology. Finally, the reaction with o-halosulfonates has been studied. The best substrates are o-chlorononaflates, which lead to indoles in very high yield. The reaction is particularlyappropriate for the synthesis of the challenging 6-substituted indoles. In view of the availability of o-chlorophenols, which are direct precur sors of the chlorononaflates, this reaction represents an efficient entry into indoles substituted in the six-membered ring. The concept is illustrated by the preparation of a 4,6-disubstituted indole from naturally occurring anethole.
- Barluenga, Jose,Jimenez-Aquino, Agustin,Aznar, Fernando,Valdes, Carlos
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supporting information; experimental part
p. 4031 - 4041
(2009/09/04)
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- Decoupling deprotonation from metalation: Thia-fries rearrangement
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(Chemical Equation Presented) Label-enabled: Studies with 2H-, 18O-, and 34S-labeled aryl triflates show that lithium diisopropylamide-mediated thia-Fries rearrangement proceeds through an irreversible ortho deprotonation (see scheme; DIPA = diisopropylamine, LDA = lithium diisopropylamide). In contrast, ortho metalation results exclusively in the generation of a benzyne.
- Dyke, Alan M.,Gill, Duncan M.,Harvey, Jeremy N.,Hester, Alison J.,Lloyd-Jones, Guy C.,Munoz, M. Paz,Shepperson, Ian R.
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supporting information; experimental part
p. 5067 - 5070
(2009/03/11)
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- On the preparation of ortho-trifluoromethyl phenyl triflate
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In contrast to an earlier report advocating a copper-mediated trifluoromethylation of ortho-iodophenyl triflate, ortho-trifluoromethyl phenyl triflate may be prepared simply by reacting the corresponding phenol with triflic anhydride in the presence of a
- Gill, Duncan,Hester, Alison J.,Lloyd-Jones, Guy C.
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p. 2547 - 2548
(2007/10/03)
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- A complementary method to obtain N-acyl enamides using the Heck reaction: Extending the substrate scope for asymmetric hydrogenation
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A series of N-acyl enamides were prepared using the Heck reaction. Asymmetric hydrogenation provided protected amines in up to 99% ee. A method to prepare N-acyl enamides is reported that is complementary to the existing protocols. Heck reaction of a vari
- Harrison, Paul,Meek, Graham
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p. 9277 - 9280
(2007/10/03)
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- A simple preparation of aryl methanesulfonates by thermal decomposition of dry arenediazonium O-benzenedisulfonimides in methanesulfonic acid
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Aryl methansulfonates 3 (18 examples) were easily prepared by thermal decomposition of dry arenediazonium o-benzenedisulfonimides 1 in methanesulfonic acid (2). The reactions were carried out at temperatures between 60 and 120°C for times between 0.5 and 8 h. The aryl methanesulfonates were obtained in reproducible yield of 70-90%, with few exceptions. In all cases the o-benzenedisulfonimide (4) could be recovered in good yields which can then be reused to prepare the salts 1. When thermal decomposition of salts 1 was carried out in trifluoromethanesulfonic acid (5) at 90-120°C for 1-2 h, aryl trifluoromethanesulfonates 6 were obtained in 73-78% yield (3 examples).
- Barbero, Margherita,Degani, Iacopo,Dughera, Stefano,Fochi, Rita,Perracino, Paolo
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- Nickel- and Palladium-Catalyzed Homocoupling of Aryl Triflates. Scope, Limitation, and Mechanistic Aspects
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Whereas the direct reduction of aryl triflates affords mainly phenols and some arenes, the presence of a catalytic amount of palladium or nickel results in the formation of biaryls. The homocoupling is performed in the presence of an electron source, either a cathode or zinc powder. A judicious choice of the metal (nickel or palladium), the ligand (monodentate or bidentate phosphine), and the reduction process (electrochemical or chemical) allows the synthesis of functional symmetrical biaryls. Nickel and palladium complexes ligated by bidentate ligands such as NiCl2(dppf) and Pd(OAc)2 + 1 BINAP are very efficient for the homocoupling of 1-naphthyl triflate, since the dimer was obtained in almost quantitative yield. However, the homocoupling is sensitive to steric hindrance, excluding for the moment the synthesis of atropisomers. The homocoupling proceeds via an activation of the C - O bond of the aryl triflate by a palladium(0) (or a nickel(0)) complex, providing an intermediate arylpalladium(II) (or nickel(II)) complex that after activation by electron transfer affords a new complex able to undergo a second oxidative addition with the aryl triflates.
- Jutand, Anny,Mosleh, Adil
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p. 261 - 274
(2007/10/03)
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- A Facile Preparation of Aryl Triflates. Decomposition of Arenediazonium Tetrafluoroborate Salts in Trifluoromethanesulfonic Acid
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The thermal or photochemical decomposition of arenediazonium tetrafluoroborate salts n trifluoromethanesulfonic acid, with or without organic bases such as pyridine, provides aryl triflates in high yields.
- Yoneda, Norihiko,Fukuhara, Tsuyoshi,Mizokami, Takao,Suzuki, Akira
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p. 459 - 460
(2007/10/02)
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