Ruthenium catalyzed synthesis of secondary or tertiary amines from amines and alcohols

Unsymmetrical secondary and tertiary amines are prepared by the ruthenium catalyzed reaction of alcohols with amines, which provides highly efficient method for synthesis of cyclic amines.     

One-pot synthesis of secondary or tertiary amines from alcohols and amines via alkoxyphosphonium salts

Secondary or tertiary amines may be prepared from primary alcohols and primary or secondary amines by treating triphenylphosphine with N-bromosuccinimide (NBS) in the presence of the alcohol at low temperature, followed by addition of the amine and heating for about 1 h. The yield of amine is good to fair, decreasing sharply with sterically congested alcohols and starting amines.     

Rapid reductive-carboxylation of secondary amines. One pot synthesis of tertiary N-methylated amines

Various tertiary N-methylated amines were synthesized by using a new reductive-carboxylation approach. Secondary amines, on carboxylation with carbon dioxide under moderate reaction conditions, afforded their corresponding carbamate esters, which, on $\text{in situ}$ lithium aluminum hydride reduction, gave desired tertiary N-methylated amines in high yield.     

Expedient protocol for solid-phase synthesis of secondary and tertiary amines

[reaction: see text] An expedient solid-phase synthetic approach to secondary and tertiary amines was developed. The protocol employs conversion of resin-bound amino alcohols to the corresponding iodides, followed by iodide displacement with primary or secondary amines or with unprotected amino alcohols. This two-step procedure, affording products in good to excellent yields, is suitable for solid-phase synthesis of polyamines.     

Ruthenium-catalysed synthesis of tertiary amines from alcohols

Secondary amines have been converted into tertiary amines by reactions with primary alcohols. A catalytic system of [Ru(cymene)Cl₂]₂ with dppf has been shown to be effective for this transformation for a range of primary alcohols and secondary amines. The methodology has been applied to the one pot synthesis of Piribedil and other piperazine and morpholine-containing products.     

n-Butyllithium-mediated synthesis of N-aryl tertiary amines by reactions of fluoroarenes with secondary amines at room temperature

A simple and facile method for the synthesis of aromatic tertiary amines by amination of fluoroarenes with secondary amines in the presence of n-butyllithium at room temperature was reported.     

Preparation of secondary and tertiary amines from nitroarenes and alcohols

Various secondary amines were obtained selectively from the reaction of nitroarenes with primary alcohols in the presence of ruthenium(II) complexes having phosphine-amine ligands as the catalyst. Secondary amines could be further alkylated with a primary alcohol using the same catalyst, but different conditions.     

A one-pot synthesis of tertiary amines from amines,lactams and urethanes

A one-pot synthesis of unsymmetrical tertiary amines from amides, lactams and urethanes has been developed. The reaction is general for all cases examined with the exception of N-aryl containing examples, which are not accessible by this method.     

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.     

An efficient synthesis of tertiary amines from nitriles in aprotic solvents

Tertiary amines are utilized extensively as non-nucleophilic proton scavengers for a number of organic transformations. Herein we report the efficient syntheses of tertiary alkyl amines from their corresponding alkyl nitriles in the presence of a heterogeneous palladium catalyst and a source of dihydrogen in aprotic solvents. The reaction is atom economic, the conditions are mild, and the isolated yields are virtually quantitative. The degree of amine alkylation shows some solvent dependency; in polar protic solvents such as ethanol or methanol, the reaction affords a mixture of products with the secondary alkyl amine as the major product.     

Coordination of secondary and tertiary amines to zinc tetraphenylporphyrin

Stability constants of 46 complexes of zinc(II) tetraphenylporphyrin with primary, secondary, and tertiary amines and thermodynamic parameters of their formation (ΔG ⁰, ΔH ⁰, ΔS ⁰) in chloroform at 283–308 K have been analyzed. Probable factors responsible for enhanced stability of the complexes with ligands containing n-octyl groups are discussed. The X-ray diffraction data for the 1: 1 complex of zinc(II) tetraphenylporphyrin with di-n-octylamine are given.     

Highly efficient and diastereoselective gold(I)-catalyzed synthesis of tertiary amines from secondary amines and alkynes: substrate scope and mechanistic insights

An efficient method for the synthesis of tertiary amines through a gold(I)‐catalyzed tandem reaction of alkynes with secondary amines has been developed. In the presence of ethyl Hantzsch ester and [{(tBu)₂(o‐biphenyl)P}AuCl]/AgBF₄ (2 mol %), a variety of secondary amines bearing electron‐deficient and electron‐rich substituents and a wide range of alkynes, including terminal and internal aryl alkynes, aliphatic alkynes, and electron‐deficient alkynes, underwent a tandem reaction to afford the corresponding tertiary amines in up to 99 % yield. For indolines bearing a preexisting chiral center, their reactions with alkynes in the presence of ethyl Hantzsch ester catalyzed by [{(tBu)₂(o‐biphenyl)P}AuCl]/AgBF₄ (2 mol %) afforded tertiary amines in excellent yields and with good to excellent diastereoselectivity. All of these organic transformations can be conducted as a one‐pot reaction from simple and readily available starting materials without the need of isolation of air/moisture‐sensitive enamine intermediates, and under mild reaction conditions (mostly room temperature and mild reducing agents). Mechanistic studies by NMR spectroscopy, ESI‐MS, isotope labeling studies, and DFT calculations on this gold(I)‐catalyzed tandem reaction reveal that the first step involving a monomeric cationic gold(I)–alkyne intermediate is more likely than a gold(I)–amine intermediate, a three‐coordinate gold(I) intermediate, or a dinuclear gold(I)–alkyne intermediate. These studies also support the proposed reaction pathway, which involves a gold(I)‐coordinated enamine complex as a key intermediate for the subsequent transfer hydrogenation with a hydride source, and reveal the intrinsic stereospecific nature of these transformations observed in the experiments.     

Regio- and stereospecific synthesis of allylic tertiary amines

E and Z allylic amines have been synthesised by stereo-specific elimination of Ph₂PO₂^? from pure diastereoisomers (3) and (4).     

Low-temperature synthesis of tetraalkylureas from secondary amines and carbon dioxide

The reaction of dialkylamines with CO(2) giving tetraalkylureas can be performed at 60 degrees C. The reaction requires CCl(4), is weakly promoted by DMAN or PPh(3), and is not promoted by a Pd catalyst. A two-step procedure, in which dialkylammonium dialkylcarbamate is produced in situ and then reacted with CCl(4) and free dialkylamine, gave greater yields of urea than a simple single-stage procedure.     

Selenium dioxide catalyzed oxidation of secondary amines with hydrogen peroxide. Simple synthesis of nitrones from secondary amines

Oxidation of secondary amines with hydrogen peroxide in the presence of selenium dioxide catalyst at room temperature gives nitrones, which are versatile synthetic intermediates, highly efficiently.     

Re2O(7)-catalyzed three-component synthesis of protected secondary and tertiary homoallylic amines

Three-component synthesis of protected secondary and "for the first time" tertiary homoallylic amines is achieved from carbonyl, carbamate, and allyltrimethylsilanes using a Re(2)O(7)-catalyst under mild and open flask conditions. Excellent chemoselectivities and diastereoselectivities were observed.