Copper-catalyzed cross-coupling of chloramine salts and arylboronic acids in water: A green and practical route to N-arylsulfonamides

A green and practical method for the synthesis of N-arylsulfonamides from chloramine salts and arylboronic acids is herein developed. The reaction proceeds readily in the presence of 5?mol% of CuI and 2.5?equiv. K₂CO₃ in water at room temperature, generating a variety of N-arylsulfonamides in moderate to good yields with good functional group tolerance.     

Direct arylation of tertiary amines via aryne intermediates using diaryliodonium salts

With a strategy by using diaryliodonium salts as the precursors of benzynes, direct N-arylation of tertiary amines with diaryliodonium salts was reported. Thus, the desired aromatic tertiary amines with a wide range of substituents were synthesized in moderate to excellent yields of 55–91%.     

N- and O-arylation of pyridin-2-ones with diaryliodonium salts: base-dependent orthogonal selectivity under metal-free conditions

Metal-free N- and O-arylation reactions of pyridin-2-ones as ambident nucleophiles have been achieved with diaryliodonium salts on the basis of base-dependent chemoselectivity. In the presence of N,N-diethylaniline in fluorobenzene, pyridin-2-ones were very selectively converted to N-arylated products in high yields. On the other hand, the O-arylation reactions smoothly proceeded with the use of quinoline in chlorobenzene, leading to high yields and selectivities. In these methods, a variety of pyridin-2-ones in addition to pyridin-4-one and a set of diaryliodonium salts were accepted as suitable reaction partners.

The metal-free N- and O-arylation reactions of pyridin-2-ones with diaryliodonium salts were achieved on the basis of base-dependent chemoselectivity.     

Copper-catalyzed direct oxidation and N-arylation of benzylamines with diaryliodonium salts

<正>1 The study of reaction conditions Table S1 The optimization of the rate of copper slats and ligand a) Entry Anion Cu/ligand Yield b)(%) 1 2 3 OTf OTf OTf 10%:20% 10%:10% 5%:10% 91 65 45 a) Reaction conditions: 1a(0.60 mmol), 2a(0.20 mmol), Cu(OTf)2(x mol%), K2CO3(2.5 equiv.), 1,10-phenanthroline(y mol%), DMSO(2 mL), 150 °C, 24 h; b) isolated yields. Table S2 The optimization of the substrates' rate a) Entry 1a/2a(mmol) Yield b)(%) 1 2 3 4 5 6 0.2:0.2 0.2:0.24 0.2:0.4 0.6:0.2 0.4:0.2 1.0:0.2 54 60 58 91 73 83 a) Reaction conditions: 1a(x mmol), 2a(y mmol), Cu(OTf)2(10 mol%), K2CO3(2.5 equiv.), 1,10-phenanthroline(20 mol%), DMSO(2 mL), 150 °C, 24 h; b) isolated yields.     

Transition‐Metal‐Free N‐Arylation of Pyrazoles with Diaryliodonium Salts

A new synthetic method was developed for the N‐arylation of pyrazoles using diaryliodonium salts. The transformation does not require any transition‐metal catalyst and provides the desired N‐arylpyrazoles rapidly under mild reaction condition in the presence of aqueous ammonia solution as a mild base without the use of inert atmosphere. The chemoselectivity of unsymmetric diaryliodonium salts was also explored with large number of examples.     

Copper-Catalyzed Synthesis of Axially Chiral Biaryls with Diaryliodonium Salts as Arylation Reagents

NOBIN and BINAM derivatives harboring biaryl frameworks are recognized as a class of important atropisomers with versatile applications. Here, we present an efficient synthetic route to access such compounds through copper-catalyzed domino arylation of N-arylhydroxylamines or N-arylhydrazines with diaryliodonium salts and [3,3]-sigmatropic rearrangement. This reaction features mild conditions, good substrate compatibility, and excellent efficiency. The practicality of this protocol was further extended by the synthesis of biaryl amino alcohols.     

C‐2 Selective Arylation of Indoles with Heterogeneous Nanopalladium and Diaryliodonium Salts

A simple and efficient method to prepare synthetically useful 2‐arylindoles is presented, using a heterogeneous Pd catalyst and diaryliodonium salts in water under mild conditions. A remarkably low leaching of metal catalyst was observed under the applied conditions. The developed protocol is highly C‐2 selective and tolerates structural variations both in the indole and in the diaryliodonium salt. Arylations of both N?H indoles and N‐protected indoles with ortho‐substituted, electron‐rich, electron‐deficient, or halogenated diaryliodonium salts were achieved to give the desired products in high to excellent isolated yields within 6 to 15 h at room temperature or 40 °C.     

Efficient N-arylation of azole compounds utilizing selective aryl-transfer TMP-iodonium(III) reagents

It was determined that diaryliodonium(III) triflates bearing a trimethoxybenzene (TMP) auxiliary are more reactive than the reported selective aryl-transfer iodonium salts in the N-arylation of benzimidazoles and other types of azole compounds under catalytic conditions. The TMP-iodonium(III) salts can thus effectively facilitate the reaction at 50?°C or below, producing the corresponding N-arylated biaryls without the formation of TMP-derived coupling byproducts. Utilization of this TMP reagent under mild conditions would prevent the underlying problem of participation of the auxiliary group in the coupling reactions, which is observed while using the iodonium(III) salts that require elevated temperatures.     

Transition Metal-Free N-Arylation of Amino Acid Esters with Diaryliodonium Salts

A transition metal-free approach for the N-arylation of amino acid derivatives has been developed. Key to this method is the use of unsymmetric diaryliodonium salts with anisyl ligands, which proved important to obtain high chemoselectivity and yields. The scope includes the transfer of both electron deficient, electron rich and sterically hindered aryl groups with a variety of different functional groups. Furthermore, a cyclic diaryliodonium salt was successfully employed in the arylation. The N-arylated products were obtained with retained enantiomeric excess.     

Rhodium(III)-catalyzed direct C-7 sulfonamidation and amination of indolines with arylsulfonamides and trifluoroacetamide

A rhodium-catalyzed direct C–H sulfonamidation and amidation of C-7 position of indolines by simple and commercially available arylsulfonamides and trifluoroacetamide has been developed, affording a series of N-arylsulfonamides and N-aryltrifluoroacetamides in moderate to excellent yields, respectively. Notably, this catalytic system is highly convenient on mmol scale.     

Fluoride-Promoted Ligand Exchange in Diaryliodonium Salts

Diaryliodonium salts are shown to undergo rapid, fluoride-promoted aryl exchange reactions at room temperature in acetonitrile. Aryl exchange is shown to be exquisitely sensitive to the concentration of fluoride ion in solution; fast exchange is observed as the fluoride concentration approaches a stoichiometric amount at 50 mM substrate concentration. The reaction is slowed, but not halted if benzene is the solvent, indicating that free fluoride ion or a four-coordinate anionic I(III) species may be responsible for the exchange. The fluoride-promoted aryl exchange reaction is general and allows direct measurement of the relative stabilities of diaryliodonium salts featuring different aryl substituents. The aryl exchange reaction may be of practical use for the preparation of hitherto inaccessible diaryliodonium salts, thus it also has implications for labeling radiotracers for molecular imaging with ¹⁸F-fluoride (t_1/2 = 109.7 min).     

Redox initiated cationic polymerization: Silane‐N‐aryl heteroaromatic onium salt redox couples

In this article, a new route for the synthesis of N‐aryl heteroaromatic onium salts by the direct copper catalyzed arylation of pyridine, substituted pyridines, isoquinoline, and acridine with diaryliodonium salts is described. It was demonstrated that these N‐aryl heteroaromatic onium salts undergo facile platinum or rhodium‐catalyzed reduction by silanes bearing Si? H groups. The reduction of N‐aryl heteroaromatic onium salts generates Brønsted acids. When this redox reaction was carried out in situ in the presence of an appropriate monomer, cationic polymerization was observed. Using this approach, the cationic polymerizations of epoxides, oxetanes, 1,3,5‐trioxane, styrene, and vinyl ethers were carried out. The use of optical pyrometry to monitor the redox initiated cationic polymerizations of some representative multifunctional monomers is described. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

An Efficient Method for the Synthesis of N-Acylsulfonamides: One-pot Sulfonylation and Acylation of Primary Arylamines under Solvent-Free Conditions

Summary. The preparation of N-acylsulfonamides is described using primary amines, arylsulfonyl chlorides and acyl chlorides. Reaction of primary aryl amines with arylsulfonyl chlorides in the presence of NaHCO₃ produced N-arylsulfonamides, which reacted in situ with benzoyl chloride furnishing the corresponding N-benzoyl-N-arylsulfonamides in 72–96% yields. Accordingly, 4-nitrobenzoyl chloride and 3,5-dinitrobenzoyl chloride were used as acylating agents. All the reactions were carried out under solvent-free conditions at room temperature and the products were isolated after simple work-up in high yields and purity.     

Palladium-catalyzed arylation/cyclization/desulfonation cascades toward 4-aryl quinolin-2(1H)-ones with diaryliodonium salts

Palladium-catalyzed cascades of arylation/cyclization/desulfonation of ortho-aminocinnamate esters by using diaryliodonium salts afforded a wide range of 4-aryl quinolin-2(1H)-ones. As such, the desired 4-aryl quinolin-2(1H)-ones with potential biological activity has been synthesized in the yields of 34–96%.     

Direct metal-free O-arylation of Biginelli 4-aryl-6-methyl-pyrimidine-2(1H)-one derivatives using diaryliodonium salts

4-Aryl-6-methyl-pyrimidine-2(1H)-one scaffolds of Biginelli type were subjected to C–O cross-coupling reactions using symmetrical diaryliodonium salts under transition metal-free conditions to afford 2-aryloxy pyrimidine derivatives in good to excellent yields.     

Fe-based metal-organic frameworks for the synthesis of N-arylsulfonamides via the reactions of sodium arylsulfinates or arylsulfonyl chlorides with nitroarenes in water

A newly developed chemoselective reaction of sodium arylsulfinates or arylsulfonyl chlorides with nitroarenes has been disclosed. The chemistry, in which non-toxic water and recyclable iron-based metal-organic frameworks are employed as the solvent and catalyst, respectively, provides an efficient approach for the generation of N-arylsulfonamides, which are widely present in biologically active compounds and drugs, rendering this methodology attractive to both synthetic and medicinal chemistry.     

Synthesis of Cyclic and Acyclic ortho-Aryloxy Diaryliodonium Salts for Chemoselective Functionalizations

Two regioselective, high-yielding one-pot routes to oxygen-bridged cyclic diaryliodonium salts and ortho-aryloxy-substituted acyclic diaryliodonium salts are presented. Starting from easily available ortho-iodo diaryl ethers, complete selectivity in formation of either the cyclic or acyclic product could be achieved by varying the reaction conditions. The complimentary reactivities of these novel ortho-oxygenated iodonium salts were demonstrated through a series of chemoselective arylations under metal-catalyzed and metal-free conditions, to deliver a range of novel, ortho-functionalized diaryl ether derivatives.     

Palladium-catalyzed redox cascade for direct β-arylation of ketones

Herein we report a full article about the detailed design and development of two palladium-catalyzed redox cascade methods that enable direct β-arylation of ketones. Palladium-catalyzed ketone dehydrogenation, aryl-X bond activation and conjugate addition were merged into a redox-neutral catalytic cycle. Non-metal-based aryl electrophiles were used as both the oxidant and the aryl source. The β-arylation with aryl iodides was achieved site-selectively with Pd(TFA)₂/P(i-Pr)₃ as the precatalyst and AgTFA as the iodide scavenger. Both cyclic and linear ketones can react to give β-aryl ketones with excellent functional group tolerance. The β-arylation with diaryliodonium salts was realized without stoichiometric heavy metal additives, and proved to be redox-neutral. A wider substrate scope regarding aryl groups and ketones was obtained for the arylation with diaryliodonium salts, and the possible involvement of palladium nanoparticles as the active catalyst was examined and discussed.     

Redox cationic polymerization: The diaryliodonium salt/ascorbate redox couple

Strong Brønsted acids are produced on reduction of diaryliodonium salts containing anions of the type BF₄^?, AsF₆^?, PF₆^?, SbF₆^? by ascorbic acid and its derivatives in the presence of catalytic amounts of copper salts. The cationic polymerizations of cyclohexene oxide, tetrahydrofuran, and s-trioxane were studied using the diaryliodonium salt/ascorbate redox couple.     

Truce-Smiles Rearrangement of Diaryliodonium Salts in Ionic Liquids

The Truce-Smiles rearrangement is an intramolecular S_NAr reaction, enabling the formation of a new arene carbon-carbon bond with sufficiently strong carbon-centered nucleophile. Reported here are ortho-tosylmethylene functionalized diaryliodonium salts, which can undergo an unprecedented Truce-Smiles rearrangement in ionic liquids, resulting in sulfonyl-substituted ortho-iodo diarylmethanes as a powerful class of building blocks in chemical synthesis. The protocol features aryliodo moiety as a hyper nucleofuge, facilitating the formation of Meisenheimer complex within the migratory system.