Reductive monoalkylation of aromatic and aliphatic nitro compounds and the corresponding amines with nitriles

[reaction: see text] A simple, selective, rapid, and efficient procedure for the synthesis of secondary amines from the reductive alkylation of either aliphatic or aromatic nitro compounds and the corresponding amines is reported. Ammonium formate is used as the hydrogen source and Pd/C as the hydrogen transfer catalyst. The reaction is carried out at room temperature. The rate differences for the preferential formation of secondary over tertiary products are due to both steric and electronic factors.     

Reductive N-alkylation of aromatic amines and nitro compounds with nitriles using polymethylhydrosiloxane

The potential utility of polymethylhydrosiloxane (PMHS) as a reducing agent for reductive N-alkylation of aromatic amines and nitro compounds using nitriles as an alkylating agent and Pd(OH)₂/C as a catalyst is described. The application of this method for the synthesis of several heterocyclic compounds is also reported.     

催化转移氢化还原腈类化合物成胺

本文报道了在碱性条件下, 用水合肼处理氯化镍(NiCl2.6H2O)得到活性镍催化剂, 不经分离直接用于催化转移氢化还原腈类化合物成胺。方法温和简便, 收率中等(35～82%)。α, β-不饱和腈还原时收率较低(12～17%)。     

Reductive monoalkylation of nitro aryls in one-pot

The scope of the serendipitous reductive monoalkylation of ethyl (4-methoxy-3-nitrophenyl) acetate taking place during reduction of the nitro functionality to the corresponding primary amine when treated with hydrogen (1 atm) over Pd/C (10%) in ethanol is investigated. Upon prolonged reaction time the reaction conducted in ethanol and methanol yields significant amount of the corresponding secondary amines, while when performed in n-butanol and i-propanol it only resulted in the formation of a small amount of the corresponding secondary amines. Further development of the reductive monoalkylation reaction provided conditions that facilitate conversion of a range of different nitro aryls in one-pot to the corresponding secondary benzyl amino aryls in mostly good to excellent yields. This is accomplished by using hydrogen (1 atm) over Pd/C (10%) as reducing agent and benzaldehyde as the benzyl source combined with a stepwise reaction sequence. This chemistry was further extended to the formation of substituted benzyl amino aryls. The yields of the latter products varied dramatically depending on the substitution patterns associated with the benzaldehyde. However, by altering the reaction conditions it was possible to improve the yields of the benzylated products.     

Accelerated benzylation reaction utilizing dibenzyl carbonate as an alkylating reagent

Ionic liquids can effectively accelerate slow N-benzylation reactions utilizing dibenzyl carbonate as an alkylating reagent. By applying microwave irradiation in the presence of the same ionic liquid, additional rate enhancement was accomplished.     

Synthesis of poly(sulfonium cation) as an alkylating reagent

Methyl 4-phenylthiophenyl sulfoxide is polymerized to poly(methyl-4-phenylthiophenylsulfonium) in poly(phosphoric acid) with a yield higher than 90%. The demethylation of poly(sufonium cation) is examined to control the composition ratio of the thiophenylene unit in the polycation. The polycation is soluble in common solvents due to the alternative structure of phenylene sufide and phenylenesulfonium cation and is easily converted to poly(phenylene sulfide) through the demethylation with a nucleophile. The poly(sulfonium cation) can be applicable as an alkylating agent for phenol, aniline and benzoic acid to the corresponding to anisole, N-methyl aniline, N,N-dimethyl aniline and benzoic methyl ester, respectively, with high conversion through the demethylation. These products can be isolated without a complicated purification because poly(phenylene sulfide) is precipitated in the mixture as the side product due to the poor solvent solubility.     

Tributyl- or tribenzylbismuth-copper diacetate system as an alkylating reagent for alcohols

Tributyl- and tribenzylbismuth react with aliphatic alcohols in the presence of copper diacetate to give dialkyl ethers, with yields of 0.10–0.25 moles per mole of the organobismuth compound.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2109–2111, December, 1993.     

Detection of aromatic amines using lead tetraacetate as the reagent

Summary Intense colors are immediately produced when primary, secondary and tertiary aromatic amines are reacted with lead tetraacetate in glacial acetic acid, methanol, acetonitrile, benzene or dioxane. This color reaction forms the basis of a rapid spot test for the detection of aromatic amines.

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Zusammenfassung Primäre, sekundäre und tertiäre aromatische Amine reagieren mit Bleitetraacetat in Eisessig, Methanol, Acetonitril, Benzol oder Dioxan unter sofortiger intensiver Farbbildung. Auf der Grundlage dieser Reaktion lassen sich aromatische Amine rasch auf der Tüpfelplatte nachweisen.

     

Synthesis of primary arylselenoamides by reaction of aryl nitriles with Woollins' reagent

[Structure: see text] The reaction of aryl nitriles with Woollins' reagent followed by water affords a variety of primary arylselenoamides in 60-100% yield. The first crystal structures of two primary selenoamides are reported.     

Reductive spiroannulation of nitriles with secondary electrophiles

The scope of reductive decyanation and spiroannulation reactions has been expanded to include secondary electrophiles for potentially useful transformations. Secondary phosphates and chlorides, as well as terminal epoxides, cyclize in a stereospecific fashion. Both endo and exo modes of cyclization were observed with terminal epoxides.     

Selective N-alkylation of amines using nitriles under hydrogenation conditions: facile synthesis of secondary and tertiary amines

Nitriles were found to be highly effective alkylating reagents for the selective N-alkylation of amines under catalytic hydrogenation conditions. For the aromatic primary amines, the corresponding secondary amines were selectively obtained under Pd/C-catalyzed hydrogenation conditions. Although the use of electron poor aromatic amines or bulky nitriles showed a lower reactivity toward the reductive alkylation, the addition of NH(4)OAc enhanced the reactivity to give secondary aromatic amines in good to excellent yields. Under the same reaction conditions, aromatic nitro compounds instead of the aromatic primary amines could be directly transformed into secondary amines via a domino reaction involving the one-pot hydrogenation of the nitro group and the reductive alkylation of the amines. While aliphatic amines were effectively converted to the corresponding tertiary amines under Pd/C-catalyzed conditions, Rh/C was a highly effective catalyst for the N-monoalkylation of aliphatic primary amines without over-alkylation to the tertiary amines. Furthermore, the combination of the Rh/C-catalyzed N-monoalkylation of the aliphatic primary amines and additional Pd/C-catalyzed alkylation of the resulting secondary aliphatic amines could selectively prepare aliphatic tertiary amines possessing three different alkyl groups. According to the mechanistic studies, it seems reasonable to conclude that nitriles were reduced to aldimines before the nucleophilic attack of the amine during the first step of the reaction.     

Reductive methylation of primary and secondary amines and amino acids by aqueous formaldehyde and zinc

Amines can be methylated when treated with formaldehyde and zinc in aqueous medium. Selective mono- or dimethylation can be achieved by proper choice of pH, stoichiometry and reaction time. This method can also be applied for amino acids.     

Synthesis and molecular structures of lanthanocene amide complexes and their catalytic activity for addition of amines to nitriles

Reaction of (CH₃C₅H₄)₂LnCl(THF) with NaNHAr in a 1:1 molar ratio in THF afforded the amide complexes (CH₃C₅H₄)₂LnNHAr(THF) [(Ar = 2,6-Me₂C₆H_3, Ln = Yb (I), Y (III); Ar = 2,6-ⁱPr₂C₆H₃, Ln = Yb (II)]. X-ray crystal structure determination revealed that complexes I-III are isostructural. The central metal in each complex coordinated to two methylcyclopentadienyl groups, one amide group and one oxygen atom from THF to form a distorted tetrahedron. Complexes I-III and a known complex (CH₃C₅H₄)₂YbNⁱPr₂(THF) IV all can serve as the catalysts for addition of amines to nitriles to monosubstituted N-arylamidines. The activity depended on the central metals and amide groups, and the active sequence follows the trend IV ≈ III < I < II.     

Dibepin-2: A new color reagent for primary aliphatic amines

3-Chloro-3-[2, 3(CO), 6, 5(CO)dibenzoylene-4-pyridyl]phthalide (Dibepin-2) is an analytical color reagent for primary aliphatic amines and arylalkylamines (with the exception of ethylenediamine and 1, 2-diaminopropane). The reaction is always negative with secondary and tertiary amines.     

Pivaloylpyruvic acid as a new acylating reagent for amines

Pivaloylpyruvic acid is an efficient reagent for preparative acylation of amines. A method for the synthesis of substituted pivaloylpyruvamides with domination of (Z)-β-keto-enol tautomer is proposed. The structure of pivaloylpyruvic acid and its amides, as well as the specific features of the reaction of pivaloylpyruvic acid with amines, are discussed.     

Sequential perfluoroalkylation and asymmetric reduction of nitriles triggered with perfluoroalkyl titanates: catalytic asymmetric synthesis of perfluoroalkyl amines

Highly enantio-enriched perfluoroalkyl amines are shown to be synthesized by perfluoroalkylation and asymmetric reduction of nitriles. Perfluoroalkylation of nitriles can be attained by the Lewis acidic perfluoroalkyl titanate reagents to give acyclic ketimines. Catalytic asymmetric hydrogenation of the acyclic ketimines affords the perfluoroalkyl amine products in up to 93% ee.