Chemospecific and ligand free CuI catalysed heterogeneous N-arylation of amines with diheteroaryl halides at room temperature

A ligand free, copper-catalyzed N-arylation reaction of amines with diheteroaryl halides in heterogeneous medium at room temperature has been developed. The protocol is very effective for low boiling amines and useful for amines available in aqueous solution. The reaction gives chemospecific arylation of amines with diheteroaryl halides in the mixture monoheteroaryl halides, diheteroaryl halides and carbocyclic aryl halides. The reaction is also chemospecific with respect to arylation of aliphatic amines. Monoarylated piperazines were also synthesized at room temperature following this protocol.     

A C-13 study of the reaction of 2,4,6-triarylpyrylium cations with amines

The reaction of primary and secondary amines with 2,4,6-triarylpyryliums is shown by C-13 NMR to proceed by fast ring opening to a vinylogous amide; in the case of primary amines this closes slowly to a pyridinium salt. The reaction in DMSO gives the pyridinium salt quantitatively when 2 moles of amines are used, with less amine significant quantities of a diketone intermediate are produced which results in slower conversion.     

Chlorotrimethylsilane activation of acylcyanamides for the synthesis of mono-N-acylguanidines

A simple and efficient one-pot method for the synthesis of monoprotected guanidines is presented. Treatment of an acylcyanamide with chlorotrimethylsilane generates a reactive N-silylcarbodiimide capable of guanylating a variety of amines. Typically the reaction is complete in 15 min for primary and secondary aliphatic amines at rt. Hindered amines and anilines are also competent nucleophiles but require extended reaction times.     

Kinetics of the reaction of the 2,4,6-tri-tert-butylphenoxyl radical with aromatic amines under quasiequilibrium conditions,and the dissociation energy of the N-H bond in aromatic amines

We have studied the kinetics of the reaction of the 2,4,6-tri-tert-butylphenoxyl radical with 11 aromatic amines under quasiequilibrium conditions. The equilibrium constant for each amine was determined from the kinetic results. These values, together with their temperature dependence, were used to calculate the dissociation energy of the N-H bond in the 11 aromatic amines. By using earlier results for the reaction of the aroxyl radical with cumyl hydroperoxide, catalyzed by aromatic amines, we have calculated the rate constants for the reaction of 10 aminyl radicals with cumyl hydroperoxide and of cumylperoxy radicals with 10 aromatic amines.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 743–749, April, 1990.     

Trifluoroacetylation of amines with trifluoroacetic acid in the presence of trichloroacetonitrile and triphenylphosphine

We developed a mild and convenient trifluoroacetylation process for amines using a combination of trichloroacetonitrile and triphenylphosphine. The reaction that we designed is applicable to the trifluoroacetylation of a wide variety of amines, including amines with stereogenic centers, which underwent trifluoroacetylation without racemization.     

ZrCl4 as a new and efficient catalyst for the opening of epoxide rings by amines

Zirconium(IV) chloride catalyses the nucleophilic opening of epoxide rings by amines leading to the efficient synthesis of β-amino alcohols. The reaction works well with aromatic and aliphatic amines in short times at room temperature in the absence of solvent. Exclusive trans stereoselectivity is observed for cyclic epoxides. Aromatic amines exhibit excellent regioselectivity for preferential nucleophilic attack at the sterically less hindered position during the reaction with unsymmetrical epoxides. However, in case of styrene oxide, selective formation of the benzylic amine was observed during the reactions with aromatic amines.     

Development of a General Non‐Noble Metal Catalyst for the Benign Amination of Alcohols with Amines and Ammonia

The N‐alkylation of amines or ammonia with alcohols is a valuable route for the synthesis of N‐alkyl amines. However, as a potentially clean and economic choice for N‐alkyl amine synthesis, non‐noble metal catalysts with high activity and good selectivity are rarely reported. Normally, they are severely limited due to low activity and poor generality. Herein, a simple NiCuFeO_x catalyst was designed and prepared for the N‐alkylation of ammonia or amines with alcohol or primary amines. N‐alkyl amines with various structures were successfully synthesized in moderate to excellent yields in the absence of organic ligands and bases. Typically, primary amines could be efficiently transformed into secondary amines and N‐heterocyclic compounds, and secondary amines could be N‐alkylated to synthesize tertiary amines. Note that primary and secondary amines could be produced through a one‐pot reaction of ammonia and alcohols. In addition to excellent catalytic performance, the catalyst itself possesses outstanding superiority, that is, it is air and moisture stable. Moreover, the magnetic property of this catalyst makes it easily separable from the reaction mixture and it could be recovered and reused for several runs without obvious deactivation.     

Reaction of Free Methyl Cation with (Isobutylamino)trimethylsilane in the Gas Phase. A Radiochemical and Quantum-Chemical Study

The reaction of free methyl cation with (isobutylamino)trimethylsilane was studied by the radiochemical method. Like with organic amines and silazane, the reaction occurs by two channels: condensation and proton transfer. Proton transfer remains to be the major reaction channel, while its contribution is less that with amines and silazane. The radiochemical and quantum-chemical methods were used to show that the condensation and proton-transfer complexes decompose primarily via Si-N bond cleavage.     

Transition-metal-free nucleophilic allylic substitutions of Morita–Baylis–Hillman bromides with aliphatic and aromatic amines

A simple protocol for the preparation of functionalized allylic amines under mild, transition-metal-free conditions from the reaction of Morita–Baylis–Hillman (MBH) bromides with amines is described herein. The treatment of the MBH bromides with various amines in the presence of NaI and Et₃N in aqueous acetone solution and at room temperature affords the corresponding functionalized allyl amines in moderate to good yields (45–87%). The reaction is rapid and carried out at room temperature.     

Regiochemical control in the amination reaction of phenanthridine-7,10-quinones

The reaction of substituted phenanthridine-7,10-quinones with amines to construct novel aminophenanthridinequinone derivatives as antitumor agents is described. The regiochemistry of the amination reaction is discussed in terms of inductive and steric effects of remote substituents to the quinone ring, which control the direction of the conjugate addition of the amines across the quinone double bond. Evidences on the significant in vitro antitumor activities of some of the obtained aminoquinones, are reported.     

Investigations on the formation of 4-aminobicyclo[2.2.2]-octanones

Benzylidene acetone reacts with thiocyanates derived from secondary amines in a one-pot reaction to give 4-aminobicyclo[2.2.2]octan-2-ones. The reaction mixture was investigated for the presence of possible intermediates using GC-MS. These intermediates - diketones and enamines - were prepared and exposed to the same reaction conditions to examine the reaction mechanism. The reaction of ethyl styryl ketone with thiocyanates of secondary amines yielded cyclohexanone derivatives instead of the expected bicyclo- octanones. Their structures were established by means of a single crystal structure analysis.     

Multicomponent one-pot procedure for the synthesis of free alpha-chiral amines from aldehydes

[reaction: see text] The synthesis of free alpha-chiral amines by a one-pot multicomponent procedure from commercially available starting materials is described. This enantioselective reaction involves a catalytic asymmetric addition of dialkylzinc reagents to N-diphenylphosphinoylimines with use of an air-stable precatalyst complex 1. The alpha-chiral amines are prepared with a one-pot procedure from alkyl and aryl aldehydes in good yield (41-90%) and with excellent enantioselectivity (90-97% ee).     

均相催化的醇和胺借氢反应

醇和胺的借氢反应是一种制备胺类化合物的绿色途径。本文介绍了借氢反应的概念,并重点介绍了均相催化的醇和胺之间借氢反应的起源、重要进展以及未来的发展趋势。     

氰基衍生化制备胺的研究进展

胺是有机分子中最常见且重要的结构之一,广泛存在于天然产物分子、药物、染料、塑料等的分子结构中,开发合成胺的有效方法在化学工业中具有很高的需求但仍充满挑战。在诸多已知有机胺的合成方法中,以氰基为前体还原衍生化制备胺被认为是一条原子经济且绿色可行的方案。然而,氰基中存在稳定的碳氮三重键,还原过程涉及较多中间体,而部分中间体活性比氰基更高,因此反应受还原剂、催化剂、反应条件的影响很大,由氰基选择性制备目标胺结构仍充满挑战。本文从氰基的基本电子结构与反应活性出发,综述了近年来以氰基为原料的官能团胺基化反应,对部分重要反应的催化剂和反应机理做了简要讨论,为设计氰基制胺催化剂和应用工艺提供了新的视角。     

Effect of amine nature on reaction mechanism: aminolyses of o-4-nitrophenyl thionobenzoate with primary and secondary amines

Pseudo-first-order rate constants (k(obs)) have been measured spectrophotometrically for reactions of O-4-nitrophenyl thionobenzoate (2) with a series of primary and acyclic secondary amines. The plots of k(obs) vs amine concentration are linear for the reaction of 2 with primary amines. The slope of the Br?nsted-type plot for the reaction of 2 with primary amines decreases from 0.77 to 0.17 as the amine basicity increases, indicating that the reaction proceeds through a zwitterionic addition intermediate in which the rate-determining step changes from the breakdown of the intermediate to the reaction products to the formation of the intermediate as the amine basicity increases. On the other hand, for reactions with all the acyclic secondary amines studied, the plot of k(obs) vs amine concentration exhibits an upward curvature, suggesting that the reaction proceeds through two intermediates, e.g., a zwitterionic addition intermediate and an anionic intermediate. The microscopic rate constants (k(1), k(-)(1), k(2), and k(3) where available) have been determined for the reactions of 2 with all the primary and secondary amines studied. The k(1) value is larger for the reaction with the primary amine than for the reaction with the isobasic acyclic secondary amines, while the k(-)(1) value is much larger for the latter reaction than for the former reaction. The k(3) value for the reaction with secondary amine is independent of the amine basicity. The small k(2)/k(-)(1) ratio is proposed to be responsible for the deprotonation process observed in aminolyses of carbonyl or thiocarbonyl derivatives.     

A novel solid-phase synthesis of highly diverse guanidines: reactions of primary amines attached to the T2 linker

The reaction of primary amines with the T2 diazonium resin generates polymer-bound triazenes, which can in turn be acylated by the addition of isothiocyanate. The formed thioureas are readily transformed into the corresponding guanidines by the reaction with amines in the presence of mercury(II) oxide, tosyl chloride, or silver nitrate. This reaction sequence furnishes trisubstituted guanidines that are potentially useful pharmacophores.     

N-Benzyloxycarbonylation of amines in the ionic liquid [TPA][l-Pro] as an efficient reaction medium

An efficient method for the N-benzyloxycarbonylation of amines is described. The reaction of amines with Cbz-Cl in the ionic liquid [TPA][l-Pro] afforded the corresponding N-Cbz derivatives in excellent yields. The method is versatile for the preparation of a wide variety of N-Cbz derivatives of aliphatic and aromatic amines.     

General molecular weight-lowering side reaction in the thermal condensation of aromatic methyl esters with aromatic amines and hydrazides

The direct thermal condensation of aromatic methyl esters with aromatic amines and hydrazides was studied. Using model compounds, it was learned that N-methylation of amines (both aromatic and aliphatic) and hydrazides is inherent at temperatures required for condensation polymerization. This side reaction prevents attainment of high molecular weight polyamides, polyhydrazides, or polyoxadiazoles from the corresponding difunctional aromatic monomers by heat alone. Reported catalysts for the condensation reaction do not prevent the side reaction.     

Advances in the field of the synthesis of amino derivatives of terpenoids

Information on the synthesis of amino derivatives of monoterpenes by the reduction of oximes by the Leuckart reaction, and by the reductive amination of ketones by amines and nitriles is generalized. The stereochemistry of the amines formed as the result of the above-mentioned reactions is discussed.     

Factors affecting the efficiency and stereoselectivity of α-amino acid synthesis by the Petasis reaction

The use of chiral secondary amines containing only one branched substituent has been shown to give optimal yields and stereoselectivities in the preparation of α-amino acids using the Petasis reaction. While the use of chiral primary amines generally gives products in low to moderate diastereoselectivity, chiral secondary amines generally give products in >95:5 diastereoselectivity. Additionally, the use of amines with two chiral (and by definition, branched) N-alkyl substituents results in significantly reduced yields with respect to to secondary amines with one or no branched N-alkyl substituents.