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.     

Effects of solvent and base on the palladium-catalyzed amination: PdCl2(Ph3P)2/Ph3P-catalyzed selective arylation of primary anilines with aryl bromides

A readily accessible catalytic system, PdCl₂(Ph₃P)₂/Ph₃P, was developed for the selective arylation of primary anilines with aryl bromides. The strong influence of solvents and bases on the catalytic activity was observed. In refluxing o-xylene, triphenylphosphine shows high efficiency for Pd-catalyzed intermolecular amination reactions. By changing the bases, mono- and diarylation of primary amines could be selectively achieved in high yields. Moreover, the catalytic system showed good toleration for the steric hindrance of anilines. A series of N,N,N′,N′-tetraaryl-1,1′-biphenyl-4,4′-diamines, important intermediates of OLED hole transport materials, were synthesized facilely via coupling reactions between 4,4′-diaminobiphenyls and aryl bromides.     

Cu2O/1-(2-methylhydrazine-1-carbonyl)-isoquinoline 2-oxide catalyzed C-N cross-coupling reaction in aqueous media

An experimentally simple, efficient, and inexpensive catalyst system was developed for the N-arylation of imidazole, indole, pyrrole, alkyl alcohol amines, and alkyl amines with aryl iodides and bromides. The reaction proceeds in water-ethanol media at 120 °C for 12 h with Cu₂O as the catalyst, 1-(2-methylhydrazine-1-carbonyl)-isoquinoline 2-oxide (L2) as the ligand, NaOH as the base to generate a wide range of N-arylated products in moderate to excellent yields. Aqueous medium, ease of operation, and broad substrate scope give the process a benign environmental profile.     

Pd2dba3/P(i-BuNCH2CH2)3N: a highly efficient catalyst for the one-pot synthesis of trans-4-N,N-diarylaminostilbenes and N,N-diarylaminostyrenes

A Pd₂dba₃/P(i-BuNCH₂CH₂)₃N catalyzed one-pot synthesis of unsymmetrically substituted trans-4-N,N-diarylaminostilbenes and both symmetrically and unsymmetrically substituted N,N-diarylaminostyrene derivatives is reported. The procedure involves two or more palladium catalyzed sequential coupling reactions (an amination and an inter-molecular Heck reaction) in one-pot using the same catalyst system with two different aryl halides, including aryl chlorides and hetero aryl halides as the coupling partners.     

Palladium-catalyzed highly regioselective and stereoselective arylation of electron-rich allylamines with aryl bromides

A palladium-catalyzed, highly efficient Heck arylation of electron-rich N,N-diprotected allylamine derivatives with a wide range of aryl bromides under ligand-free conditions has been developed. In the presence of Pd(OAc)₂ and an appropriate additive, the reaction proceeds with excellent regioselectivity and stereoselectivity, leading exclusively to the γ-arylated (E)-allylamine products in good to excellent yields. It was found that the choice of solvent, olefin, additive and temperature has an important influence on the reaction. Worthy of note is that good results were observed only when using N,N-diprotected allylamines containing carbamate moiety, and the steric properties of allylamines also have important impacts on the regiocontrol. The use of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) or HQ (hydroquinone) as the additive is also crucial for securing a faster reaction rate. This method provides a straightforward approach for the efficient synthesis of various γ-arylated, linear (E)-allylamines.     

Palladaphosphacyclobutenes as catalysts in Heck and Suzuki reactions

Heck reactions of aryl halides with various olefins and Suzuki reactions of aryl halides with phenylboronic acid catalyzed by palladaphosphacyclobutene have been investigated. The scope of the Heck reaction has been investigated in N,N‐dimethylacetamide at 140 °C using NaOAc as base. Using 0.1% molar ratio of palladaphosphacyclobuyenes, aryl bromides were converted into 1,2‐substitutedethene products in good to high yields through coupling with both vinylarenes and acrylates. Actived aryl chloride reacted with styrene to afford 1,2‐substitutedethene products in moderate yields. The scope of the Suzuki reaction has been conducted in toluene at 110 °C using Cs₂CO₃ as base. Using 0.1% molar ratio of palladaphosphacyclobutene, aryl bromides reacted with phenylboronic acid to afford diaryl derivatives in excellent yield. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis of macrocycles containing two pyridine and two polyamine moieties via Pd-catalyzed amination

The synthesis of macrocycles containing two pyridine and two polyamine fragments was carried out by the Pd-catalyzed amination of 2,6-dihalopyridines using polyamines and dioxadiamine. Two alternative approaches were elaborated and compared: via intermediate formation of N^α,N^ω-bis(6-halopyridin-2-yl)polyamines or via 2,6-bis(polyamino)substituted pyridines. The yields of linear and cyclic products were shown to be strongly dependent on the nature of the starting polyamines and that of the halogen atom.     

An efficient, mild, and selective Ullmann-type N-arylation of indoles catalyzed by copper(I) complex

A wide range of N-arylated indoles are selectively synthesized through intermolecular C(aryl)-N bond formation from the corresponding aryl iodides and indoles through Ullmann-type coupling reactions in the presence of a catalytic amount of easily available N,N,N′,N′-tetramethyl-BINAM-CuI complex under very mild reaction conditions.     

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.     

N-Arylation of aliphatic, aromatic and heteroaromatic amines catalyzed by copper bis(2,2,6,6-tetramethyl-3,5-heptanedionate)

Copper bis(2,2,6,6-tetramethyl-3,5-heptanedionate) was found to be an efficient catalyst for N-arylation of aliphatic, aromatic and heteroaromatic amines with aryl iodides/bromides under mild conditions. The system tolerated a variety of hindered and functionalized amines/aryl halides and the desired N-aryl amines were obtained in good to excellent yields.     

General and highly efficient fluorinated-N-heterocyclic carbene–based catalysts for the palladium-catalyzed Suzuki–Miyaura reaction

A general and highly efficient trifluoromethylated-N-heterocyclic carbene (NHC)-based catalyst for the palladium-catalyzed Suzuki–Miyaura reaction was reported. In the presence of the catalyst, reactions of non-activated aryl chlorides and triflates with aryl boronic acids occurred at room temperature with good to excellent yields (63–98%). In addition, catalysts generated from a combination of Pd(OAc)₂/imidazolium salt 6a is not only effective for the coupling of heteroaryl boronic acid with aryl halides and heteroaryl halides, but also efficient for coupling of other heteroaryl halides and heteroaryl boronic acids. Finally, the catalyst is highly effective for Suzuki–Miyaura reaction of aryl bromides and chlorides with 0.01–0.1 mol % loading if the temperature was raised at refluxed THF/H₂O.     

Three-component one-pot process to propargylic amines and related amide and sulfonamide compounds: application to the construction of 2-(aminomethyl)benzofurans and indoles

An efficient palladium-copper-catalyzed three-component assembling of propargyl halides, aryl or heteroaryl halides, and secondary amines is described. A wide variety of tertiary propargylic amines were synthesized in good to excellent yields from easily accessible starting materials. This three-component assembling was also effective when using potassium phthalimide or di-tert-butyliminodicarbonate instead of secondary amines. Consequently, it provides a quick entry to N-protected propargylic amines suitable intermediates for the synthesis of primary and secondary propargylic amines. In a similar way, related compounds including propargylic amide, carbamate and sulfonamide derivatives were efficiently obtained. This catalytic domino three-component process has been applied successfully to the construction of functionalized 2-(aminomethyl)benzo[b]furan or indole derivatives of biological interest.     

NHC-initiated cascade,metal-free synthesis of quinoxaline derivatives under solvent-free conditions

2,3-Diaryl quinoxaline derivatives have been efficiently synthesized by cascade, metal-free, and solvent-free reaction of aryl aldehydes with aryl 1,2-diamines initiated by N-heterocyclic carbene. Compared with reported methods, this procedure has the advantages of easy work-up, reduced energy consumption, and elimination of solvent waste, hazards, and toxicity. A group of potentially bioactive compounds has been prepared for biomedical screening.     

A novel isocyanide-based three-component reaction: a facile synthesis of substituted 2H-pyran-3,4-dicarboxylates

An efficient method for synthesis of 2H-pyran-3,4-dicarboxylates using the three-component reaction of dithiocarbamates, dialkyl acetylenedicarboxylates, and isocyanides in solvent-free conditions is described. In these reactions, synthesis of dithiocarbamates is possibly based on the one-pot reaction of secondary amines, CS₂, and alkyl halides in solvent-free conditions without using a catalyst. The mild reaction conditions and high yields of the reaction exhibit the good synthetic advantage of these methods.     

Synthesis of tertiary aryl amines of various aryl halides and secondary amines using ortho‐palladated complex of tribenzylamine

The activity of dimeric [Pd{C₆H₄(CH₂N(CH₂Ph)₂)} (μ‐Br)]₂ complex as an efficient, air‐ and moisture‐tolerant catalyst was investigated in amination reactions of various aryl halides with secondary amines. Substituted tertiary aryl amines were produced in excellent yields and short reaction times using catalytic amounts of this dimeric complex in DMSO at 120°C. Copyright © 2013 John Wiley & Sons, Ltd.     

Palladium-catalyzed carbonylative synthesis of N-cyanobenzamides from aryl iodides/bromides and cyanamide

A novel and convenient protocol for the synthesis of N-cyanobenzamides starting from readily available aryl halides and cyanamide via palladium-catalyzed aminocarbonylation has been developed. The protocol utilizes Mo(CO)₆ as the CO source or CO(gas) and affords the desired N-cyanobenzamides in moderate to good yields.     

Co2(CO)8 as a convenient in situ CO source for the direct synthesis of benzamides from aryl halides (Br/I) via aminocarbonylation

A fast, mild, and functional group tolerant method for the direct synthesis of benzamides from aryl halides (Br, I) via aminocarbonylation, using solid Co₂(CO)₈ as a convenient CO source, has been demonstrated. The developed method is applicable to a wide variety of 1° and cyclic and acyclic 2° amines. Nitro substituted (o, m and p) aryl halides have easily been converted to the corresponding benzamides, without the reduction of the nitro group, in high yields using this in situ carbonylation methodology under microwave irradiation.     

The highly efficient Suzuki-Miyaura cross-coupling reaction using cyclopalladated N-alkylferrocenylimine as a catalyst in aqueous medium at room temperature under ambient atmosphere

A series of N-alkyl-substituted cyclopalladated ferrocenylimines were used in palladium-catalyzed Suzuki-Miyaura cross-coupling reactions of aryl halides in room temperature and CH₃OH/H₂O media under aerobic conditions. As for the catalysts, the length of N-alkyl chains has no significant effect on the catalytic activity. Using 0.01 mol% of dimer 3a in the presence of K₂CO₃ as base offered excellent yields in the reaction of activated and non-activated aryl bromides with phenylboronic acid.     

Iodine-Mediated One-Pot Synthesis of 1,4,5-Substituted Pyrazoles from MBH Acetates via Allyl Hydrazone Intermediate

Herein, we report the regioselective one-pot synthesis of 1,4,5-trisubstituted pyrazoles by reacting Morita-Baylis-Hillman (MBH) acetates derived from aryl aldehydes with alkyl or aryl hydrazines in the presence of iodine under aerobic conditions. The reaction proceeds through sequential S_N2′ nucleophilic substitution of substituted hydrazine onto the MBH acetate, I₂-catalyzed oxidation of the allylic hydrazine to allylic hydrazone, heating-induced intramolecular aza-Michael reaction and cyclization, and oxidative aromatization. The key intermediate, the s-trans allyl hydrazones were isolated in good yields by performing the reactions at room temperature. However, the allyl hydrazones prepared from the MBH acetates of aliphatic aldehydes did not furnish the pyrazole owing to the absence of an activated methylene group in the substrate. The synthetic applications of the pyrazoles in Ugi reactions, decarboxylative halogenation, Pd-catalyzed benzoylation of the N-aryl ring, and metal-free tetrazole synthesis has been demonstrated.     

NHC triggered cascade metal-free synthesis of 2,3-diarylated indoles under solvent-free conditions

A new cascade strategy to the synthesis of 2,3-diarylated indoles via the metal-free reaction of aryl aldehyde and aryl amine triggered by N-heterocyclic carbene (NHC) under solvent-free conditions, has been disclosed. The protocol has the advantages of easy work-up, high yields, wide application scope, and an environmentally benign procedure compared with the reported methods.