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.     

Efficient synthesis of tertiary amines from secondary amines

Reliable N-alkylations of secondary amines have been developed. By using DIAD and TPP (or PS-TPP) a variety of secondary amines can be converted to the corresponding tertiary amines in good to excellent yields with diverse alkylhalides; no formation of quaternary amine salts are observed. These protocols are amenable to combinatorial chemistry libraries, and are also useful for the syntheses of secondary amines by an acid lysis of the cleavable tertiary amino resins.     

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.     

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.     

Oxone-sodium nitrite mediated N-nitrosamines formation under mild conditions from secondary amines

Abstract

Herein, we report an efficient synthesis of N-nitrosamines from cyclic, aliphatic, benzylic, and aromatic secondary amines via a novel straightforward, efficient, and mild chemical process using sodium nitrite and Oxone in methanol as a solvent at 0–5?°C. The demonstrated methodology accounts well for the parameters like cost-effective, short reaction time, clean and safe handling along with good to excellent yields.     

Copper-catalyzed direct oxidative C-H amination of benzoxazoles with formamides or secondary amines under mild conditions

A facile, efficient, and practical method for copper-catalyzed direct C-H amination of benzoxazoles with formamides or secondary amines has been developed. The system can be performed in the absence of external base and only requires O(2) or even air as oxidant. A variety of substituted benzoxazol-2-amines were synthesized with moderate to excellent yield.     

温和条件下钒催化氧化胺、醇和胺直接合成亚胺(英文)

开发了钒催化氧化胺、醇和胺直接合成亚胺催化体系,无须额外的添加剂或促进剂,空气作为环境友好的氧源,温和条件下,能高收率地得到各种对称和非对称亚胺,并且催化剂非常容易制备和使用.该催化体系对含杂原子亚胺的合成也非常有效.     

All-carbon-substituted vinylsilane stable to TBAF: synthesis of allyldimethylvinylsilane and its Pd-catalyzed cross-coupling under mild conditions

[reaction: see text] Allyldimethylvinylsilanes 3 are easily synthesized by the reaction of silylallylmetals, generated from 1 by n-BuLi/t-BuOK, with carbonyl compounds in the absence or presence of metal halides. They can tolerate 2 equiv of TBAF in THF at room temperature for at least 6 h but can be easily activated in the presence of a palladium catalyst and TBAF to perform the cross-coupling reaction with aryl iodides at room temperature.     

Reaction of primary amines with Pt/C catalyst in water under microwave irradiation: a convenient synthesis of secondary amines from primary amines

Upon microwave irradiation in water, Pt/C converts primary amines into secondary amines in good yield via retro-reductive and reductive amination.     

Direct and mild palladium-catalyzed aerobic oxidative synthesis of imines from alcohols and amines under ambient conditions

By ligand, TEMPO, and base screening, we developed a mild and green one-pot imine synthesis from alcohols and amines via a low-loading palladium-catalyzed tandem aerobic alcohol oxidation-dehydrative condensation reaction that can be readily carried out in open air at room temperature.     

酞菁锌高效催化以二氧化碳、含氢硅烷和有机胺为原料合成甲酰胺类衍生物

目前为了有效地利用好CO2,主要策略有以下几种:(1)"水平途径"——无价态及能量变化,譬如生成尿素、环状碳酸酯、聚碳酸酯及噁唑烷酮类衍生物等;(2)"垂直途径"——有价态及能量变化,譬如直接加氢转化成碳一产品(甲酸、甲醛、甲醇、甲烷)等;(3)"对角线途径"——有价态及能量变化,即结合石油化工原料将CO2还原生成醇、醚、羧酸、亚胺、酰胺、酯等系列高附加值的精细有机化工产品.其中以二氧化碳和含氢硅烷为原料,通过有机胺的N-甲酰化反应合成甲酰胺类衍生物符合绿色化学和可持续发展的要求.基于仿生催化CO2分子活化的基本理论,我们借鉴强极性的有机溶剂可有效活化硅氢键的性质,创新性地将廉价易得的酞菁锌(ZnPc)作为类酶催化剂,并以化学计量的N,N'-二甲基甲酰胺(DMF)为添加剂,构成组分新颖并高效绿色的类酶协同催化体系,实现了在温和反应条件下高效高选择性地合成甲酰胺类衍生物.研究发现:以苯硅烷作为还原剂,当加入0.5 mol%ZnPc和2 mmol DMF,在25℃和0.5 MPa下仅需反应6 h,可得到收率为99%的N-甲基甲酰苯胺.更值得注意的是,当以更易得的聚甲基氢硅烷(PMHS)为还原剂时,加入5 mol%ZnPc和1 mL DMF,在80℃和1 MPa下反应8 h,N-甲基甲酰苯胺的收率也高达99%.实验结果表明:添加剂DMF可以通过溶剂化和强极性作用高效活化含氢硅烷中的Si?H键,然后具有亲电性的金属活性中心能够稳定氢负离子生成高活性锌氢中间体.即ZnPc/DMF之间的协同催化作用能够促进氢化物从含氢硅烷转移到CO2分子,进而有利于CO2分子的高效活化.综上所述,利用类酶催化剂反应专一性的特点,通过有机胺的N-甲酰化反应,实现了以CO2和含氢硅烷为原料在温和条件下甲酰胺类衍生物的绿色高效合成.这对于设计和开发更加高效的催化体系具有一定的指导作用和借鉴意义.     

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.     

Expedient synthesis of secondary amines bound to indole resin and cleavage of resin-bound urea, amide and sulfonamide under mild conditions

Highly efficient, new protocols for the attachment of primary amines to indole aldehyde resin using Ti(OⁱPr)₄-NaBH₄ and CH(OMe)₃-NaBH₃CN-HOAc are reported. Mild cleavage conditions for the release of urea, amide and sulfonamide products from the solid support using 1% trifluoroacetic acid (TFA) are developed.     

Sonocatalyzed facile synthesis of 2-aryl benzoxazoles using MnO2 nanoparticles as oxidant agent under mild conditions

Nano MnO₂ was found to be an efficient oxidant agent for the synthesis of 2-substituted benzoxazoles through one-pot reaction of o-aminophenol and different aromatic aldehydes in acetonitrile under ultrasonic irradiation. This method was performed under mild conditions with high yields, inexpensive and readily available oxidant agent, facile and easy experimental procedure, simple purification of final products, and short reaction times. The prepared nano MnO₂ has been characterized by FTIR, XRD, and SEM techniques. The pure products were identified and characterized by physical and spectroscopic data such as; melting point, IR, ¹H NMR, and ¹³C NMR.     

Metal-free synthesis of allylic amines by cross-dehydrogenative-coupling of 1,3-diarylpropenes with anilines and amides under mild conditions

Dehydrogenative cross-coupling reaction of primary anilines, secondary anilines, carboxamides, and sulfonamides with 1,3-diarylpropenes to form a series of allylic amines promoted by DDQ have been realized. Both monoallylation and diallylation products can be selectively synthesized when primary anilines are used as the starting materials. The method may provide a wide scope of allylamines in scientific research including biologically active compound library construction.     

Synthesis of carbamoyl azides from primary amines and carbon dioxide under mild conditions

Treatment of amines under a carbon dioxide atmosphere with tetramethylphenylguanidine (PhTMG) and diphenylphosphoryl azide (DPPA) in acetonitrile below 0 degrees C provides carbamoyl azides in high to excellent yields. In addition, epimerization is not observed when optically pure alpha-amino esters are used as substrates.     

Chemoselective N-nitrosation of secondary amines under heterogeneous and mild conditions via in situ generation of HNO_2

A wide variety of secondary amines are chemoselectively subjected to N-nitrosation reaction with treatment of citric acid and NaNO2 in the presence of wet SiO2(50%,w/w)in dichloromethane at room temperatture under heterogeneous conditions.The N-nitrosation method is very simle and products can be easily isolated with good to high yields.