Magnesium nitride as a convenient source of ammonia: preparation of dihydropyridines

Magnesium nitride (Mg 3N 2) has been investigated for the preparation of dihydropyridines. This is a commercially available, bench-stable solid that generates ammonia upon treatment with protic solvents. The main features of the process are the facile reaction setup and good yields obtained in the majority of cases.     

New convenient method for preparation of amides of 1-adamantylthioacetic acids

The reaction of 4-(1-adamantyl)-1,2,3-thiadiazole with potassium tert-butylate followed by treating with acetyl chloride and amine results in the formation of 1-adamantylthioacetic acid amides in moderate or good yields.     

A convenient new procedure for converting primary amides into nitriles

An operationally simple and high-yielding procedure has been developed for the conversion of primary amides to the corresponding nitriles, using ethyl dichlorophosphate/DBU as the mild dehydrating agent.     

Borate esters as convenient reagents for direct amidation of carboxylic acids and transamidation of primary amides

Simple borates serve as effective promoters for amide bond formation with a variety of carboxylic acids and amines. With trimethyl or tris(2,2,2-trifluoroethyl) borate, amides are obtained in good to excellent yield and high purity after a simple work-up procedure. Tris(2,2,2-trifluoroethyl) borate can also be used for the straightforward conversion of primary amides to secondary amides via transamidation.     

Acceptorless dehydrogenative synthesis of primary amides from alcohols and ammonia

The highly desirable synthesis of the widely-used primary amides directly from alcohols and ammonia via acceptorless dehydrogenative coupling represents a clean, atom-economical, sustainable process. Nevertheless, such a reaction has not been previously reported, and the existing catalytic systems instead generate other N-containing products, e.g., amines, imines and nitriles. Herein, we demonstrate an efficient and selective ruthenium-catalyzed synthesis of primary amides from alcohols and ammonia gas, accompanied by H₂ liberation. Various aliphatic and aromatic primary amides were synthesized in high yields, with no observable N-containing byproducts. The selectivity of this system toward primary amide formation is rationalized through density functional theory (DFT) calculations, which show that dehydrogenation of the hemiaminal intermediate into primary amide is energetically favored over its dehydration into imine.

An efficient and selective synthesis of primary amides from alcohols and ammonia, with H₂ evolution, has been achieved by an unprecedented acceptorless dehydrogenative process catalyzed by a pyridine-based PNN–ruthenium pincer complex.     

Heterogeneously catalyzed synthesis of primary amides directly from primary alcohols and aqueous ammonia

In the presence of a manganese oxide based octahedral molecular sieve (OMS-2), a range of primary amides could be synthesized directly from primary alcohols and ammonia. The observed catalysis was heterogeneous, and the recovered catalyst could be reused many times without an appreciable loss of its catalytic performance.     

Synthesis of primary aromatic amides by aminocarbonylation of aryl halides using formamide as an ammonia synthon

Primary aromatic amides were prepared by a palladium-catalyzed aminocarbonylation reaction of aryl halides in high yields (70-90%) using formamide as the amine source. The reactions require a palladium catalyst in combination with a nucleophilic Lewis base such as imidazole or 4-(dimethylamino)pyridine (DMAP). Aryl, heteroaryl, and vinyl bromides and chlorides were converted to the primary amides under mild conditions (5 bar, 120 degrees C) using 1 mol % of a palladium-phosphine complex. Best results were obtained in dioxane using triphenylphosphine as the ligand and DMAP as the base. For activated aryl bromides, a phosphine-to-palladium ratio of 2:1 was sufficient, but less reactive aryl bromides or aryl chlorides required ligand-to-palladium ratios up to 8:1 in order to stabilize the catalyst and achieve full conversion. The influence of catalyst, base, solvent, pressure, and temperature was studied in detail. The mechanism of the reaction could be clarified by isolating and identifying the reaction intermediates. In addition, methylamides and dimethylamides were prepared by the same method using N-methylformamide and N,N-dimethylformamide as the amine source.     

Zirconium nitride as a highly efficient nitrogen source to synthesize the metal nitride clusterfullerenes

Metal nitride clusterfullerenes(NCFs)have significant applications in molecular electronics,biomedical imaging,and nonlinear optical devices due to their unique structures.However,their wide applications are limited by the production quantity.In this work,the yields of metal nitride clusterfullerenes M3N@C80(M=Y,Sc,Gd)were greatly enhanced by utilizing zirconium nitride(Zr N)as an efficient nitrogen source for the arc-discharge method.Compared with the traditional synthetic route using N2gas as nitrogen source,the Zr N inside graphite tube can be vaporized simultaneously with metal and graphite,and then afford the high concentration of nitrogen atoms in the arc region,which will promote the formation of metal nitride clusterfullerenes finally.The Zr N can promote the yields of Y3N@C80,Sc3N@C80and Gd3N@C80,revealing the universal applicability of Zr N as a highly efficient nitrogen source.Specifically,the yield of Sc3N@C80was greatly improved when adding Zr N,and it shows over double yield compared to traditional synthetic route using N2gas.In addition,Zr N can also enhance the yields of paramagnetic azametallofullerene M2@C79N due to the high concentration of nitrogen atoms in the arc region.This new method enhances the production quantity of metal nitride clusterfullerenes and azametallofullerenes,and it will greatly promote the research and application of these molecular carbon materials.     

Sample preparation and gas chromatography of primary fatty acid amides

A method for the isolation of bio-active primary fatty acid amides (PFAM's) from total lipid extract by solid-phase extraction (SPE) was developed and validated. The lowest mass of amide to be loaded and recovered by this method was detected as 0.5 microg using 500 mg of normal phase adsorbent. The isolated PFAM's were separated and quantified by GC/MS and percent recoveries were calculated. An HP-5MS column was able to provide base line separation between the saturated and unsaturated PFAM's whereas clear resolution between geometric and positional isomers having the same number of carbons was obtained using a BPX70 column. The separated amides were all 18 carbon analogs of cis-9-octadecenoamide (oleamide). Detection limits in the single ion monitoring mode were found to be on the order of 10 pg in a 1 microl injection. Solid phase extraction of amides from total lipid extract before GC/MS analysis provides clean detection and interference free analysis.     

A convenient catalytic approach to synthesize straight boron nitride nanotubes using synergic nitrogen source

Straight boron nitride nanotubes (BNNTs) with pure hexagonal phase were conveniently prepared by heating the mixture of Mg(BO₂)₂ · H₂O, NH₄Cl, NaN₃ and Mg powder in an autoclave at 600 °C for 20–60 h. These BNNTs had diameters mainly ranging 30–300 nm and lengths up to 5 μm, and a majority of them had at least one closed end. Besides the traditional end tips, additional cone-like tips were frequently found to be attached on the BNNTs. The effects of temperature, reactants and the possible mechanism of the catalytic formation of the BNNTs are discussed.     

A convenient method for the preparation of primary amines using tritylamine

A simple method for the preparation of primary amines by treating N-tritylamines with trifluoroacetic acid has been established. The N-tritylamines were prepared by the reaction of alkyl halides or alkyl p-toluenesulfonates with tritylamine, or by the reaction of alkyl bromides with lithium tritylamide.     

DABCO-bis(sulfur dioxide), DABSO, as a convenient source of sulfur dioxide for organic synthesis: utility in sulfonamide and sulfamide preparation

The charge-transfer complex generated from the combination of DABCO and sulfur dioxide, DABSO, is a bench-stable colorless solid suitable for use in organic synthesis as a replacement for gaseous sulfur dioxide. The complex can be combined with Grignard reagents to form sulfinates, which can then be converted in situ to a series of sulfonamides. Alternatively, reaction with anilines and iodine leads to the formation of a series of sulfamides. Cheletropic addition between DABSO and 2,3-dimethylbutadiene provides the corresponding sulfolene.     

β-Sulfinyl acrylate esters as a convenient source of alkane- and arenesulfenate anions

Methyl acrylate esters bearing alkane- and arenesulfinyl units on the 2-carbon liberate sulfenate anions upon nucleophilic attack. The sulfenates are readily captured through sulfur alkylation. When a sulfenate derived from R-cysteine is generated, diastereoselective benzylation is observed.     

Enantioselective iridium-catalyzed allylic amination of ammonia and convenient ammonia surrogates

Iridium-catalyzed, asymmetric allylation of ammonia as a nucleophile occurs with stereoselectivity to form a symmetric diallylamine, and related allylation of the inexpensive ammonia equivalent potassium trifluoroacetamide or the highly reactive ammonia equivalent lithium di-tert-butyliminodicarboxylate forms a range of conveniently protected, primary, alpha-branched allylic amines in high yields, high branched-to-linear regioselectivities, and high enantiomeric excess. The reactions of ammonia equivalents were conducted with a catalyst generated from a phosphoramidite containing a single stereochemical element.     

Highly enantioselective access to primary propargylamines: 4-piperidinone as a convenient protecting group

[reaction: see text] We report a highly enantioselective, catalytic three-component coupling of aldehydes, alkynes, and 4-piperidone hydrochloride hydrate to afford the corresponding tertiary propargylamines in useful yields. The selective cleavage of the piperidone protecting group using either ammonia/EtOH or a polymer-supported scavenger amine furnishes primary propargylamines.     

Direct use of dioxygen as an oxygen source: catalytic oxidative synthesis of amides

The first transition-metal-catalyzed direct oxidative synthesis of amides by using dioxygen as an oxygen source has been developed under mild conditions, in which DBU was used as the key additive. The present methodology, which utilizes dioxygen as an oxidant and oxygen source and cheap copper salts as catalysts, opens up an interesting and attractive avenue for the synthesis of amide functionality.     

N-Acylbenzotriazoles: neutral acylating reagents for the preparation of primary, secondary, and tertiary amides

Readily available N-acylbenzotriazoles 2a-q efficiently acylate aqueous ammonia and primary and secondary amines to give primary, secondary, and tertiary amides in good to excellent yields. The wide applicability of the procedure is illustrated by the preparation of (i) alpha-hydroxyamides from alpha-hydroxy acids and of (ii) perfluoroalkylated amides.