Rapid Microwave Induced Palladium Catalyzed Amination of Aryl Bromides

 The palladium-catalyzed coupling reaction of aryl bromides with various amines under microwave irradiation was studied using PdCl₂ [P(o-tolyl)₃]₂ which gave various aryl amines in good yields. The reactions were carried out under normal atmospheric conditions.     

An Exceedingly Mild,Green Synthesis of Substituted N‐3‐diaryl‐1,8‐naphthyridin‐2‐amine Derivatives and Their Antimicrobial Activity

An exceedingly and highly efficient procedure has been described for the synthesis of substituted N‐3‐diaryl‐1,8‐naphthyridin‐2‐amines by the reaction of 2‐chloro‐3‐aryl‐1,8‐naphthyridines with various anilines in the presence of N‐methyl‐2‐pyrrolidone and K₂CO₃ under thermal green solvent‐free conditions. The significant features of this green reaction include very good yields in purity, simple experimental, short reaction time, easy workability, and avoidance of toxic solvents. All synthesized compounds have been evaluated for their antibacterial activity.     

Copper bis(2,2,6,6-Tetramethyl-3,5-heptanedionate)–Catalyzed Coupling of Sodium Azide with Aryl Iodides/Boronic Acids to Aryl Azides or Aryl Amines

This work reports an efficient protocol for the coupling reaction of aryl iodides/boronic acids with sodium azide to aryl azides/amines in the presence of copper bis(2,2,6,6-tetramethyl-3,5-heptanedionate) Cu(TMHD)₂ catalyst. The Cu(TMHD)₂ catalyst is a structurally well-defined, O-containing, air- and moisture-stable, transition-metal complex and works at mild reaction conditions. It was observed that aryl azides can be reduced further to corresponding aniline derivatives using the same catalyst under basic reaction conditions for a prolonged period.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Transition metal-free amination of aryl halides—A simple and reliable method for the efficient and high-yielding synthesis of N-arylated amines

A simple and reliable reaction protocol for the clean, fast, and high-yielding synthesis of various N-arylated amines derived from reactions of aryl halides with various (also sterically hindered) amines under transition metal-free reaction conditions is presented. Dioxane and KN(Si(CH₃)₃)₂ were found to be the ideal solvent and base for this transformation. The conversion rates and yields observed are excellent and in the majority of the reactions performed significantly higher than that obtained in their catalyzed versions. Furthermore, the selective synthesis of 6-halopyridin-2-amines and asymmetric pyridine-2,6-diamines (derived from consecutive reactions of 2,6-dibromopyridine and 2,6-dichloropyridine, respectively, with different amines) is possible in almost quantitative yields (relative to 2,6-dihalopyridine) within very short reaction times. Purification of the 6-halopyridin-2-amine intermediates is not necessary, allowing the synthesis of pyridine-2,6-diamines in ‘one-pot’. However, catalysts are in many cases not required to efficiently and selectively couple aryl halides with amines, making transition metal-free versions of the Buchwald-Hartwig reaction extremely attractive for the synthesis of N-arylated amines with substrates containing substituents on the aryl halide, which either promote regioselectivity and/or do not require regioselective aminations.     

Palladium Complexes Based on Ylide-Functionalized Phosphines (YPhos): Broadly Applicable High-Performance Precatalysts for the Amination of Aryl Halides at Room Temperature

Palladium allyl, cinnamyl, and indenyl complexes with the ylide-substituted phosphines Cy₃P⁺−C⁻(R)PCy₂ (with R=Me ( L1 ) or Ph ( L2 )) and Cy₃P⁺−C⁻(Me)PtBu₂ ( L3 ) were prepared and applied as defined precatalysts in C−N coupling reactions. The complexes are highly active in the amination of 4-chlorotoluene with a series of different amines. Higher yields were observed with the precatalysts in comparison to the in situ generated catalysts. Changes in the ligand structures allowed for improved selectivities by shutting down β-hydride elimination or diarylation reactions. Particularly, the complexes based on L2 (joYPhos) revealed to be universal precatalysts for various amines and aryl halides. Full conversions to the desired products are reached mostly within 1 h reaction time at room temperature, thus making L2 to one of the most efficient ligands in C−N coupling reactions. The applicability of the catalysts was demonstrated for aryl chlorides, bromides and iodides together with primary and secondary aryl and alkyl amines, including gram-scale applications also with low catalyst loadings of down to 0.05 mol %. Kinetic studies further demonstrated the outstanding activity of the precatalysts with TOF over 10.000 h⁻¹.     

Facile N-tert-butoxycarbonylation of amines using La(NO3)3·6H2O as a mild and efficient catalyst under solvent-free conditions

Facile N-tert-butoxycarbonylation of amines is described by the treatment of various primary, secondary, benzylic and aryl amines with di-tert-butyl dicarbonate in the presence of catalytic amounts of La(NO₃)₃·6H₂O under solvent-free conditions at room temperature to afford N-tert-butylcarbamates in excellent yields.     

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.     

Microwave Assisted Mannich Reaction of Terminal Alkynes on Alumina

Summary.  Terminal alkynes, secondary amines, and formaldehyde undergo a Mannich reaction at room temperature in the presence of CuCl on Al₂O₃ without any organic solvent as reaction medium. The reaction can be promoted by microwave irradiation and is complete within one minute. Received May 2, 2001. Accepted (revised) June 25, 2001     

CeCl3·H2O/NaI-Promoted stereoselective synthesis of 2,4-disubstituted chiral tetrahydroquinolines

d-Glycals readily undergo cyclization with aryl amines in the presence of CeCl₃·7H₂O-NaI under mild and neutral conditions to afford a novel sugar derived tetrahydroquinoline derivatives in good yields with high stereoselectivity. The stereochemistry of the products was assigned by using various NMR studies.     

无溶剂一锅法Al(ClO4)3催化合成α-氨基膦酸酯

以无水高氯酸铝为催化剂, 将芳香醛、芳香胺及亚磷酸酯在无溶剂条件下一锅法反应, 高效地合成了α-氨基膦酸酯, 该催化剂优于其它已发现的催化剂[如Mg(ClO₄)₂, BiCl₃, AlCl₃等], 建立了一种适用于含有钝化基团的芳香胺的α-氨基膦酸酯的新合成方法.     

Protonated primary amines induced thymine quintets studied by electrospray ionization mass spectrometry and density functional theory calculations

As the novel magic number clusters of nucleobases, the thymine quintets induced by ammonium ion (NH₄⁺), and particularly by its derivatives such as protonated alkyl amines and protonated aryl amines, have been studied by electrospray ionization mass spectrometry (ESI‐MS) and density functional theory (DFT) calculations. The DFT‐optimized geometry of NH₄⁺ induced thymine quintet ([T₅ + NH₄]⁺) reveals some new features including three additional hydrogen bonds between NH₄⁺ and its surrounding thymine molecules when compared with that of the alkali metal ions induced thymine quintets. In addition, the fourth hydrogen atom of NH₄⁺ is sticking out the assembly, and, thus, it might be replaced by an organic group R to form the protonated primary amine induced thymine quintet ([T₅ + R ? NH₃]⁺), a hypothesis that has been confirmed by both DFT calculations and ESI‐MS experiments. Furthermore, the relative abilities of the different protonated primary amines for inducing the thymine quintets are investigated by ESI‐MS competition experiments, and the results have shown a clear trend of stronger ability as the alkyl chain gets longer or as the aryl ring gets larger for the alkyl amines or the aryl amines. Two basic influence factors are consequently identified: one is the ability of the alkyl amine to accept proton, another is the π–π stacking interaction between the aryl ring and the π‐surface of the thymine molecule(s), whose explanations are strongly supported by multiple types of thermochemical data, various control experiments and DFT calculations. Copyright © 2014 John Wiley & Sons, Ltd.     

Mild and efficient Pd(PtBu3)2‐catalyzed aminocarbonylation of aryl halides to aryl amides with high selectivity

This work describes a mild and efficient approach for the synthesis of aryl amides via catalytic aminocarbonylation of aryl halides with alicyclic amines using a Pd(P^t Bu₃)₂/NH₄Cl catalyst system. Under mild reaction temperature of 60°C and balloon pressure of CO, 5 mol% Pd(P^t Bu₃)₂ with a cheap NH₄Cl promoter is sufficient for high yields of aryl amides. The influence of reaction parameters such as reaction temperature, ligand type and promoter on catalytic activity was investigated. This work also discusses the catalytic intermediates in detail, and provides a plausible mechanism based on an acid chloride intermediate.     

Facile amidation of esters with aromatic amines promoted by lanthanide tris (amide) complexes

The development of catalysts capable of catalyzing amidation of esters with amines to construct amides under mild conditions is of great importance. Compared to aliphatic amines, the direct catalytic amidation of esters with less nucleophilic aromatic amines is rather difficult. Employing simple lanthanide tris (amide) complexes Ln[N (SiMe₃)₂]₃(μ-Cl)Li (THF)₃ as the catalysts, it was found a broad range of aromatic amines and esters were efficiently converted into various amides in good yields under mild conditions. A plausible mechanism for this transformation was experimentally supported as starting from an amide exchange reaction between the lanthanide tris (amide) complex and the substrate amine.     

Copper-Catalyzed Amination of Aryl Halides with Aqueous Ammonia under Mild Conditions

A Cu(I) generated in situ from CuSO₄·5H₂O/sodium ascorbate catalyzed cross‐coupling reaction of aryl halides with aqueous ammonia for the synthesis of primary aromatic amines has been developed. Key to the success included the application of aqueous ammonia under a homogeneous condition.     

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.     

CuBr/FeCl3 Catalysis: a Novel and Efficient Method for the Preparation of New Aryl (Iminomethyl)propargyl Ether Derivatives via C?H Activation of Aryl Propargyl Ethers

CuBr/FeCl₃ Catalysis as a novel and efficient method has been developed for the preparation of new aryl propargyl imine ether derivatives via C? H activation of aryl propargyl ethers, followed by reaction with imines generated from aldehydes and amines.     

trans-Pd(OAc)2(Cy2NH)2 catalyzed Suzuki coupling reactions and its temperature-dependent activities toward aryl bromides

A new catalytic system based on Pd-simple amines for Suzuki coupling reactions of aryl bromides is described. A well-defined air-stable complex, trans-Pd(OAc)₂(Cy₂NH)₂ effectively promotes Suzuki couplings of aryl bromides with a range of aryl boronic acids to give diaryl products in high yields. It also exhibits temperature-dependent activity toward aryl bromides bearing different electronic substituents under reaction conditions.     

Novel,One-Pot,Three-Component,Regioselective Synthesis of Fluorine-Containing Thiazole and Bis-3H-thiazole Derivatives Using Polyvinyl Pyridine as Heterogeneous Catalyst,and Evaluation of Their Antibacterial Activity

A convenient, one-pot, three-component regioselective synthesis of novel 2,2′-(1,4-phenylene)-bis-(3-aryl-2-substituted imino-4-aryl-3H-thiazole) derivatives from 1,4-phenylene diisothiocyanate, aryl amines, and various phenacyl bromide, and also the regioselective synthesis of 3-alkyl-2-(aryl imino)-4-cyclopropyl-5-(2′-fluorophenyl)-thiazole derivatives from alkylisothiocyanate, aryl amines, and 2-bromo-2-(2-fluorophenyl)-1-cyclopropylethanone in the presence of poly-4-vinyl pyridine as heterogenous basic catalyst are described. This efficient method produced the products at room temperature with excellent yields (82–96%). The structures of all products were characterized by spectral and elemental analyses. The antimicrobial activity of the synthesized compounds was evaluated against Salmonella enterica, Micrococcus luteus, Bacillus subtilis, and Pseudomonas aeruginosa.     

高选择性N-单甲基化芳香胺的合成

本文报道了一种高效专一性合成N-单甲基芳胺的方法。芳胺先与醋酐反应生成乙酰胺,再与碘甲烷在氢化钠作用下反应生成相应的N-甲基乙酰芳胺。在乙二醇中用酸水解高产率得到相应的N-单甲基芳胺。并将该方法用于药物中间体的合成。     

CuBr/Et3N‐Promoted Reactions of 2‐Aminobenzamides and Isothiocyanates: Efficient Synthesis of Novel Quinazolin‐4(3H)‐ones

A series of novel quinazolin‐4(3H)‐one derivatives were efficiently synthesized starting from isatoic anhydride. First, reaction of isatoic anhydride and amines in H₂O at room temperature afforded 2‐aminobenzamides. Then, CuBr/Et₃N promoted reaction of 2‐aminobenzamides and different aryl isothiocyanates in DMF at 80° afforded the title compounds in good yield.