Three-component reaction between amines,carbon disulfide and electron-deficient derivatives of chloropyridine or chlorobenzene: synthesis of 3,6-diazaspiro[4.5]deca-2,7,9-trien-6-ium chloride and dithioylcarbamates derivatives

In this study, three-component reaction of some primary and secondary amines with carbon disulfide in the presence of electron-deficient derivatives of chloropyridine or chlorobenzene in the CH₃CN as a solvent is reported. The reaction of primary amines with carbon disulfide and electron-deficient compounds of chloropyridine or chlorobenzene after 6–8 h afforded the three-component addition product. The reaction of secondary amines with carbon disulfide and electron-deficient compounds of chloropyridine or chlorobenzene after 3–4 h afforded the two-component addition product. The product(s) of reactions were purified by recrystallization or column chromatography and their structures were identified by spectroscopy techniques such as ¹H-NMR, ¹³C-NMR, IR, UV and elemental analysis. The reactions were carried out under mild conditions and without using a catalyst.     

CpIr-catalyzed N-alkylation of amines with alcohols. A versatile and atom economical method for the synthesis of amines

A versatile and highly atom economical catalytic system consisting of [Cp^∗IrCl₂]₂/NaHCO₃ (Cp^∗=pentamethylcyclopentadienyl) for the N-alkylation of amines with primary and secondary alcohols as alkylating reagents has been developed. For example, the reaction of equimolar amounts of aniline and benzyl alcohol in the presence of [Cp^∗IrCl₂]₂ (1.0 mol % Ir) and NaHCO₃ (1.0 mol %) in toluene at 110 °C gives N-benzylaniline in 94% yield. The present catalytic system is applicable to the N-alkylation of both primary and secondary amines, and only harmless water is produced as co-product. A wide variety of secondary and tertiary amines can be synthesized with high atom economy under mild and less-toxic conditions. One-pot sequential N-alkylation leading to tertiary amines bearing three different substituents is also described.     

Effect of solvent on the free energy of activation of S_N2 reaction between phenacyl bromide and amines

The kinetics of SN2 reaction between phenacyl bromide and various amines in 12 different solvents were studied. Solvent effects on the rate of this reaction and free energy of activation, ΔG# , were interpreted by applying the Abraham-Kam-let-Taft (AKT) equation. UK solvent polarity (π1*), solvent hydrogen-bond basicity (β1) and Hildebrand cohesive density energy (δH2) are those parameters which increase the rate constant and decrease ΔG# , while solvent hydrogen-bond acidity (α1) will have the compensatory effect. A comparison among obtained values of second rate constants, k2, for different amines in a given solvent indicates that the amine reactivities are highly dependent on their structures. The consequent decrease of the rate constant for different amines in any given solvent was found to be: primary > secondary> tertiary. This order results from steric effects of amines.     

Facile Synthesis of N‐Carboranyl Amines through an ortho‐Carboryne Intermediate

The efficient o‐carboryne precursor 1‐Li‐2‐OTf‐o‐C₂B₁₀H₁₀ reacts with lithium amides at room temperature to give a series of N‐carboranyl amines in moderate to high isolated yields. This reaction is compatible with a broad substrate scope from primary to secondary, alkyl to aryl amines. The reaction mechanism is also proposed on the basis of experimental results and DFT calculations. This represents the first general and efficient method for the synthesis of 1‐NR¹R²‐o‐carboranes.     

Reaction of halogenated hydrocarbon solvents with tertiary amines: Spectrophotometric and conductimetric study

Halogenated hydrocarbon solvents, SolvCl, (dichloromethane, chloroform, and 1,2‐dichloroethane) react with various types of tertiary amines, A, such as tri‐n‐buthylamine, tropane derivatives (tropine and atropine) and quinine generating a quaternary ammonium salt, N‐halogenalkylammonium chloride (SolvA⁺Cl^?). Some tertiary amines, as well as secondary and primary amines, cannot react with these solvents. This reaction has been detected and studied by both conductivity and visible spectrophotometry measures—the latter after adding a small quantity of a dye, such as bromocresol green (BCGH₂), bromophenol blue (BPBH₂), or tetrabromophenolphthaleinethyl ester (TBPEH). Both study methods permit the determination of the kinetic parameters, and they are in good agreement. The monoprotic TBPEH is the dye of the simplest mechanism, useful to study kinetics of amines of uncertain behavior as quinine, while BPBH₂ is the best dye for quantitative determinations. Kinetics for this reaction are of first order for both amine, A, and solvent, SolvCl; activation energy, E_a, and frequency factor are also determined. Rate constants increase with the amine basicity and with a reduction in the number of the halogen atoms present in the solvent. This reaction is slow but not negligible and must be considered a side reaction of these universally used solvents. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36:500–509, 2004     

Zur Umsetzung des Zweikomponentensystems Trialkylphosphit/ Tetrachlorkohlenstoff mit wasserstoffhaltigen Nucleophilen 2. Die Reaktion mit Ammoniak und Aminen

Reaction of the Two-component System Trialkylphosphite/Carbon Tetrachloride with Nucleophiles Containing Hydrogen. 2. Reaction with Ammonia and Amines Ammonia and primary amines react with the two-component system trialkylphosphite/carbon tetrachloride yielding diester-amides of phosphoric acid, (RO)₂P(O)NHR′. If an excess of amine is used compounds of the type ROP(O)(NHR′)₂ and OP(NHR′)₃ are formed too. By the reaction of (RO)₃P/CCl₄ in presence of secondary and tertiary amines the first reaction product is (RO)₂P(O)CCl₃ which yields with the amine [NRR′R″R″′]⁺[Cl₃CP(OR)O₂]^?; (R = Et, Bu).     

Synthese und Eigenschaften von Pentafluorophosphaten,YPF5− (Y = OR,NHAr), und PF5 · Amin-Addukten,PF5 · HNR2

Synthesis and Properties of Pentafluorophosphates, YPF₅^? (Y = OR, NHAr), and PF₅-Amine Adducts, PF₅ · NHR₂ In the presence of secondary amines instead of hexafluorophosphates, PF₆^?, PF₅-amine adducts, PF₅ · NHR₂, are obtained by the reaction of PCl₅ with alkylammonium fluorides in acetonitrile. The additional presence of alcohols or phenol leads to the formation of alkoxy- or aroxypentafluorophosphates, ROPF₅^?. The PF₅-amine adducts can be converted into ROPF₅^? or arylimidopentafluorophosphates, ArNHPF₅^?, resp., by treating with alcohols or aryl amines, resp.     

Supported Gold Nanoparticles for Efficient α‐Oxygenation of Secondary and Tertiary Amines into Amides

Although the α‐oxygenation of amines is a highly attractive method for the synthesis of amides, efficient catalysts suited to a wide range of secondary and tertiary alkyl amines using O₂ as the terminal oxidant have no precedent. This report describes a novel, green α‐oxygenation of a wide range of linear and cyclic secondary and tertiary amines mediated by gold nanoparticles supported on alumina (Au/Al₂O₃). The observed catalysis was truly heterogeneous, and the catalyst could be reused. The present α‐oxygenation utilizes O₂ as the terminal oxidant and water as the oxygen atom source of amides. The method generates water as the only theoretical by‐product, which highlights the environmentally benign nature of the present reaction. Additionally, the present α‐oxygenation provides a convenient method for the synthesis of ¹⁸O‐labeled amides using H₂¹⁸O as the oxygen source.     

Transamimerungen an Dimethylaminodimethylarsin

Transaminations of Dintethylarainodimethyiarsine Dimethylaminodimethylarsine (CH₃)₂As–N(CH₃)₂ reacts with secondary amines under formation of Dialkylaininodimethylarsines (CH₃)₂As–NR₂. Dimethylamine is evolved during the reaction. Eleven arsines were prepared by this method. IR and ¹H-NMR data are presented and discussed.     

Exploiting the Brønsted Acidity of Phosphinecarboxamides for the Synthesis of New Phosphides and Phosphines

We demonstrate that the synthesis of new N‐functionalized phosphinecarboxamides is possible by reaction of primary and secondary amines with PCO^? in the presence of a proton source. These reactions proceed with varying degrees of success, and although primary amines generally afford the corresponding phosphinecarboxamides in good yields, secondary amines react more sluggishly and often give rise to significant decomposition of the 2‐phosphaethynolate precursor. Of the new N‐derivatized phosphinecarboxamides available, PH₂C(O)NHCy (Cy=cyclohexyl) can be obtained in sufficiently high yields to allow for the exploration of its Brønsted acidity. Thus, deprotonating PH₂C(O)NHCy with one equivalent of potassium bis(trimethylsilyl)amide (KHMDS) gave the new phosphide [PHC(O)NHCy]^?. In contrast, deprotonation with half of an equivalent gives rise to [P{C(O)NHCy}₂]^? and PH₃. These phosphides can be employed to give new phosphines by reactions with electrophiles, thus demonstrating their enormous potential as chemical building blocks.     

Determination of molar ratio of primary secondary and tertiary amines in polymers by applying derivatization and NMR spectroscopy

A trifluoroacetic acid derivatization combined with ¹H NMR spectroscopy method for determining the molar ratio of primary, secondary, and tertiary amines in small molecules and polymers was discussed. Amines reacted with trifluoroacetic acid to form their salts RNH₃⁺, R₂NH₂⁺, and R₃NH⁺. The ¹H NMR signals of these protonated amines (NH₃⁺, NH₂⁺, and NH⁺) were separated well in the spectra. Based on the integration of these protonated amine signals, the molar ratio of primary, secondary, and tertiary amines can be calculated.     

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.     

Palladium(II)?NHC complexes containing benzimidazole ligand as a catalyst for C?N bond formation

The reaction of 2‐(2‐bromoethyl)‐1,3‐dioxane with 1‐alkylbenzimidazole derivatives results in the formation of the new benzimidazolium salts (1). The reaction of Pd(OAc)₂ with 1,3‐dialkylbenzimidazolium salts (1a–c) yields palladium N‐heterocyclic carbene (NHC) complexes (2a–c). All synthesized compounds were characterized by ¹H NMR, ¹³ C NMR, IR and elemental analysis techniques which support the proposed structures. As catalysts, these new palladium complexes offer a simple and efficient methodology for the synthesis of triarylamines and secondary amines from anilines and amines and in a single step with potassium tertiary butoxide as a base. Copyright © 2010 John Wiley & Sons, Ltd.     

Response and selectivity characteristics of alkylammonium ion-selective electrodes

A series of poly(vinyl chloride) matrix coated-wire electrodes based on dinonylnaph-thalene sulfonic acid (DNNS) selective to various alkylammonium ions was prepared and selectivity characteristics were evaluated. A set of tributylammonium electrodes was used to study the interference by a homologous series of alkylammonium ions. Selectivity coefficient (k^pot_i,j) values for alkylammonium ions at a given carbon number decreased in the order primary, secondary, tertiary, quaternary. A linear increase in log k^pot_i,j with carbon number was observed in each series. Two additional sets of electrodes selective to dodecylammonium ion and to di-n-hexylammonium ion were evaluated for response to other C-12 amines. Electrodes for primary amines showed little or no response to secondary and tertiary amines, while electrodes for tertiary amines responded strongly to primary amines and less strongly to secondary amines. The effect of structural modifications was evaluated in a study of N-substituted cydohexylamines. The dependence of the magnitude of k^pot_i,j on the concentration of the interference was determined for both strongly and weakly interfering species. For strong interferences, k^pot_i,j was observed to increase to a maximum value of characteristic concentration. For weak interferences, the k^pot_i,j variation with concentration was markedly less. Guides for estimating the response to an interfering species based on its structure and molecular weight were obtained. The results are compared to analogous solvent-extraction systems. The significance of these results is discussed in terms of quantifying different components in binary mixtures using several electrodes simultaneously.     

Effect of amines on the ceric ion-initiated polymerization of vinyl monomers. II. Polymerization of acrylonitrile by ceric ion in presence of various substituted amines

The effect of various substituted amines on the polymerization of acrylonitrile initiated by ceric ammonium sulfate has been studied in aqueous solution at 30°C. It was found that the secondary and tertiary amines considerably increased the rate of polymerization, whereas the primary amines seemed to have no effect at all. From the kinetic studies it was found that the overall polymerization rate R_p is independent of ceric ion concentration and can be expressed by the equation: R_p = k₁ [amine] [monomer] + k₂[monomer]², where k₁ and k₂ are constants (involving different rate constants). The accelerating effect of the amines was attributed to a redox reaction between the ceric ion and the amine involving a single electron transfer, the relative activity of the different amines being thus dependent on the relative electron-donating tendency of the substituents present in the amine. The mechanism of the polymerization is discussed on the basis of these results, and various kinetic constants are evaluated.     

N‐Silylation of Amines Mediated by Et3SiH/KOtBu

Silylation of primary and secondary amines is reported, using triethylsilane as the silylating reagent in the presence of potassium tert‐butoxide (KO^tBu). The reaction proceeds well in the presence of 0.2 equiv. of KO^tBu. In competition experiments, aniline is selectively silylated over aliphatic amines. Computational studies support a catalytic mechanism which is initiated by KO^tBu interacting with the silane to form KH and silylated amine. The KH then takes over the role of base in the propagation of the cyclic mechanism and deprotonates the amine. This reacts with R₃SiH to afford the product R₃SiNR′R′′ and regenerate KH.     

Spectrofluorimetric determination of aliphatic amines using a new fluorigenic reagent: 2,6-dimethylquinoline-4-(N-succinimidyl)-formate

A new amino fluorescence probe, 2,6-dimethylquinoline-4-(N-succinimidyl) formate (DMQF-OSu) has been synthesized. Based on the selective reaction of DMQF-OSu with primary and secondary aliphatic amines to yield strong fluorescence, a new spectrofluorimetric method for the determination of total aliphatic amines has been developed. At λ_ex/λ_em=324.4/416 nm, the linear calibration range was 6×10⁻⁸-6×10⁻⁶ mol l⁻¹ with the detection limit (3σ) of 1.94×10⁻¹⁰ mol l⁻¹ for the determination of aliphatic amines in weak basic media. The proposed method has been applied to the determination of aliphatic amines in tap water and lake water with the recoveries of 99-104%. Compared with the reported methods, the method presented here is rapid, simple, sensitive and feasible.     

Visible‐Light/Photoredox‐Mediated sp3 CH Functionalization and Coupling of Secondary Amines with Vinyl Azides in Flow Microreactors

Structurally diverse imidazole derivatives were synthesized by a visible‐light/[Ru(bpy)₃][(PF₆)₂]‐mediated coupling of vinyl azides and secondary amines in flow microreactors. This operationally simple and atom‐economical protocol allows the formation of three new C?N bonds through the functionalization of sp³ C?H bonds adjacent to the secondary nitrogen atom. In order to get mechanistic insight of the coupling reaction, several control experiments were carried out and discussed.     

Mannich Synthesis of Acetylenic Amino Alcohols in Aqueous Ionic Liquids

Terminal alkynols react with formaldehyde and secondary amines in aqueous ionic liquid [emim]HSO^–₄ in the presence of Cu(OAc) to afford the corresponding 1-(a-hydroxyalkyl)- or 1-(b-hydroxyalkyl)-2-(aminomethyl)acetylenes in better yields in comparison with the reaction in conventional organic solvents. The catalytic system can be easily recovered and recycled.     

Mild and Selective Activation and Substitution of Strong Aliphatic CF Bonds

A procedure for chemoselectively manipulating the strong aliphatic C?F bond with direct transformation into a C?N bond under mild conditions is reported. The activation and subsequent substitution of primary alkyl fluorides is mediated by La[N(SiMe₃)₂]₃, and results in high to excellent yields of tertiary amines. The methodology displays high selectivity towards the C(sp³)?F bond, and a variety of secondary amines are applicable as nucleophiles. Mechanistic investigations reveal a reaction that is first order with respect to [La[N(SiMe₃)₂]₃], [R¹R²NH], and [alkyl fluoride], and a 6‐membered cyclic transition state is proposed. In addition, ¹H NMR spectroscopy shows that La[N(SiMe₃)₂]₃ is the active species involved in the substitution and that protonolysis of the amine, yielding La[NR¹R²]₃, lowers the reactivity.