A rate enhancement of tert-butoxycarbonylation of aromatic amines with Boc2O in alcoholic solvents

A rate enhancement of tert-butoxycarbonylation of aromatic amines by Boc₂O in alcohols compared to aprotic solvents was demonstrated. Kinetic analysis by NMR suggested that the reaction in CD₃OD was faster than in CDCl₃ by a factor of 70. Reactions between Boc₂O and various aliphatic and aromatic amines in ethanol provided the N-Boc derivatives in good to excellent yields in short reaction times.     

Hydrothermal synthesis, characterization, and photocatalytic properties of Zn2SnO4

Nanosized Zn₂SnO₄ (ZTO) particles were successfully synthesized by a simple hydrothermal process in water/ethylene glycol mixed solution using amines (ethylamine, n-butylamine, n-hexylamine, and n-octylamine) as mineralizer. The products were characterized by X-ray diffractions (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N₂ adsorption. The results indicated that the hydrothermal conditions, such as alkaline concentration (n-butylamine), reaction temperature, solvent composition, and the kind of amines, had an important influence on the composition, crystallinity, and morphology of the product. The as-synthesized ZTO samples exhibited high activities and durabilities for photodegradation of methyl orange and the activities were mainly affected by the crystallinities of the samples. A hexagonal-shaped ZTO (H-ZTO) sample was prepared in 0.53 M of n-butylamine solution at 180 °C for 20 h and its optical properties were characterized by UV-Vis diffuse reflectance and Photoluminescence (PL) spectra. Furthermore, the photocatalytic H₂ evolution reaction from ethanol aqueous solution over H-ZTO was also investigated.     

Syntheses of phenanthridines and benzophenanthridines by intramolecular ortho-arylation of aryl amide ions with aryl halides via SRN1 reactions

The photostimulated reaction of N-(2-halo-benzyl)aryl amines with t-BuOK in liquid ammonia affords fused azaheterocycles by the S_RN1 mechanism. The starting materials are easily obtained by the reaction of 2-halo-benzyl chloride and aromatic amines to prepare the secondary amines. Through this approach, phenanthridine (90%), 4-phenylphenanthridine (87%), benzo[a]phenanthridine (98%), and benzo[c]phenanthridine (84%) were synthesized.     

Nano-ferrous ferric oxide (nano-Fe3O4): Powerful,reusable, and stable catalyst for N-Boc protection of amines

Nano-ferrous ferric oxide (nano-Fe₃O₄) efficiently catalyzed N-boc protection of amines in high yields and acceptable reaction times. Nano-Fe₃O₄ was applied as an efficient, green, heterogeneous and reusable magnetite catalyst. Clean reaction, simple purification, short reaction time and high yield were some other advantages of this compound.     

Reactions of chlorofullerene C60Cl6 with N-substituted piperazines

It was shown for the first time that reactions of C₆₀ halides with aliphatic amines provide a facile route for the synthesis of aminofullerenes, valuable precursors for water-soluble cationic fullerene derivatives. Particularly, chlorofullerene C₆₀Cl₆ and N-substituted piperazines were investigated in this work. It was shown that substitution of chlorine atoms in C₆₀Cl₆ by amine groups is accompanied by partial elimination of addends from the fullerene cage that yields mixtures of di-, tetra- and, hexaaminofullerenes as the final products. Separation of these mixtures by column chromatography resulted in isolation of pure 1,4-diaminofullerenes; this procedure gives much higher and more reproducible yields of these compounds than direct oxidative photoaddition of secondary amines to C₆₀. ESI mass spectrometry and NMR spectroscopy data showed that hexaaminofullerene isomers are major components in inseparable mixtures of polyaddition products. Polyaminofullerenes were found to be readily soluble in aqueous acids; these solutions are unstable because of a facile substitution of protonated amine groups with hydroxyls. Nevertheless, the use of other amine substrates in the investigated reaction can potentially allow the preparation of more stable water-soluble cationic fullerene derivatives for biological studies.     

Ferric sulfate [Fe2(SO4)3·xH2O]: an efficient heterogeneous catalyst for the synthesis of tetrahydroquinoline derivatives using Povarov reaction

Fe₂(SO₄)₃·xH₂O can be used as an efficient and reusable catalyst for the synthesis of pyrano- and furanotetrahydroquinolines via one-pot three-component Povarov reaction involving aromatic aldehydes, aromatic amines, and cyclic enol ethers. The catalyst is recyclable, economically viable, and environmentally benign. This protocol provides good yields and diastereoselectivity as well as applicability on a wide range of substrates.     

NbCl5-Catalyzed one-pot Mannich-type reaction: three component synthesis of β-amino carbonyl compounds

Three-component Mannich-type reaction of acetophenone, aromatic aldehydes and aromatic amines was catalyzed by NbCl₅ at ambient temperature to give various β-amino ketones in high yields.     

Synthesis of chiral vicinal C2 symmetric and unsymmetric bis(sulfonamide) ligands based on trans-1,2-cyclohexanediamine by aminolysis of N-tosylaziridines

The ring opening of N-tosylaziridines with aliphatic amines can be efficiently catalyzed by lithium perchlorate to provide derivatives of the trans-1,2-diamine in high yields. The reaction was used in desymmetrization of several cyclic N-tosylaziridines using chiral amines. Using this strategy, an efficient synthesis of chiral vicinal C₂ symmetric bis(sulfonamide) and unsymmetrical bis(sulfonamide) ligands based on trans-1,2-cyclohexanediamine was developed.     

Ferric Chloride–Promoted Efficient and Facile BOC Protection of Amines

Amines are efficiently protected as their tertiary butyloxycarbonyl (BOC) derivatives under mild reaction condition when reacted with (BOC)₂O in the presence of FeCl₃. The present method is applicable to a variety of amines including aliphatic, aromatic, and hetero aromatic amines.     

Electrophilic monofluoromethylation of O-, S-, and N-nucleophiles with chlorofluoromethane

CH₂ClF has been found to be a useful electrophilic monofluoromethylating agent for a variety of O-, S-, and N-nucleophiles. The reaction is not sensitive to the radical scavenger such as nitrobenzene, which strongly supports an S_N2 mechanism rather than an SET mechanism. Although most of these products (fluoromethyl ethers, sulfides, and amines) can be isolated with good purity, some of these compounds do intend to decompose (via defluorination) during storage. The electrophilic monofluoromethylation of carbon-nucleophiles was attempted with CH₂ClF, CH₂FI, or FCH₂OTs as monofluoromethylating agents, but with no success.     

Yb(OTf)3催化苯乙酮、芳香醛和芳香胺的Mannich反应: 三组分“一锅法”合成β-氨基酮衍生物

报道了稀土化合物Yb(OTf)₃催化的苯乙酮、芳香醛和芳香胺Mannich反应, 三组分“一锅法”合成了一系列的β-氨基酮衍生物. 该方法操作简单、条件温和、产率较高、催化剂可重复使用, 且对环境友好.     

CuPy2Cl2: A Novel and Efficient Catalyst for Synthesis of Propargylamines Under the Conventional Method and Microwave Irradiation

CuPy₂Cl₂ is an efficient catalyst for the preparation of propargylamines via three-component coupling reaction of aromatic aldehydes, amines, and aromatic alkynes stirred at 95 °C without using any solvent to afford the corresponding products in good yields. The reaction mixture was irradiated at 450 W in a microwave oven to furnish the expected products in excellent yields.     

N-tert-Butoxycarbonylation of amines using H3PW12O40 as an efficient heterogeneous and recyclable catalyst

The commercially available heteropoly acid H₃PW₁₂O₄₀ (0.5 mol %) is a very efficient and environmentally benign catalyst for N-tert-butoxycarbonylation of amines (primary, secondary) with di-tert-butyl dicarbonate at room temperature in short reaction times (<10 min). No competitive side products such as isocyanates, ureas, N,N-di-tert-butoxycarbonyls, O-Boc and oxazolidinones were observed. Chiral α-amino alcohols and esters afforded the corresponding N-Boc derivatives chemoselectively in excellent yields.     

FeCl3 as Lewis acid catalyzed one-pot three-component aza-Friedel-Crafts reactions of indoles, aldehydes, and tertiary aromatic amines

A new strategy for the synthesis of 3-diarylmethyl indoles was developed through FeCl₃ as Lewis acid catalyzed three-component aza-Friedel-Crafts reactions of indoles, aldehydes, and tertiary aromatic amines in one-pot. The reactions generated the corresponding 3-diarylmethyl indoles in good yields under mild reaction conditions by using less expensive, readily available, and environmentally benign iron catalyst. It is important to note that the key feature of this reaction is operational simplicity.     

Syntheses of polycarbonate and polyurethane precursors utilizing CO2 over highly efficient, solid as-synthesized MCM-41 catalyst

As-synthesized MCM-41 was used as a reusable, heterogeneous catalyst for the eco-friendly synthesis of cyclic carbonate precursors of polycarbonates via a cycloaddition reaction of CO₂ with epoxides. This catalyst is also efficient for the synthesis of alkyl and aryl carbamate precursors of polyurethanes via the reaction of amines, CO₂ and alkyl halides. Both these reactions were carried out under mild conditions and without using any solvent or co-catalyst. CO₂ is utilized as a raw material replacement for toxic phosgene in the conventional synthesis of these chemicals.     

A novel multi-component reaction of indole, formaldehyde, and tertiary aromatic amines

A novel multi-component reaction of indoles, formaldehydes, and tertiary aromatic amines is described for the synthesis of dialkylaminoarylated indoles using silica-supported perchloric acid (HClO₄-SiO₂) as an inexpensive and highly efficient catalyst. The key features of this multi-component reactions are operational simplicity, mild reaction conditions, regioselectivity, and recycling of catalyst.     

A novel and efficient catalytic system including TEMPO/acetaldoxime/InCl3 for aerobic oxidation of primary amines to oximes

A simple and efficient catalytic system including TEMPO/acetaldoxime/InCl₃ for aerobic oxidation of primary amines to corresponding oximes by using toluene as the solvent is described. This practical method can use O₂ as the economic and green oxidant, tolerate a wide range of substrates, which can afford the target oximes in moderate to excellent yields.     

Cs2.5H0.5PW12O40 catalyzed diastereoselective synthesis of β-amino ketones via three component Mannich-type reaction in water

A series of insoluble salts of Keggin heteropoly compounds were prepared and used as catalysts for the Mannich-type reaction of benzaldehyde, aniline, and cyclohexanone in water. Among them, Cs_2.5H_0.5PW₁₂O₄₀ showed excellent catalytic activity. Effects of surfactant, catalyst loading and temperature were studied to introduce the best reaction condition. The optimized reaction conditions were extended to Mannich reaction of various aldehydes, ketones, and amines in water. This rapid procedure afforded structurally divers β-amino ketones with major anti diastereoselectivity. Additionally, four new compounds were reported. The catalyst was recovered and reused for subsequent runs.     

Efficient and mild method for preparation of allylic amines from aziridine-2-alcohols using PPh3/I2/imidazole

Allylic amines are synthesized in good to excellent yields by treatment of aziridine-2-alcohols with PPh₃/I₂/imidazole in THF as solvent under mild conditions.     

SnCl4 and SbCl5 promoted aromatization of enamines

Aromatic amines have been synthesized efficiently from enamines using SnCl₄ and SbCl₅ in CH₂Cl₂ at room temperature.