Copper(II)-catalyzed hydration of nitriles with the aid of acetaldoxime

An efficient method for the selective hydration of nitrile to amide by employing inexpensive copper salt catalyst and commercially available acetaldoxime in environmentally friendly water is described. Under this protocol, nitriles including aromatic nitriles, heterocyclic nitriles and aliphatic nitriles were converted into the corresponding amides in good to excellent yields.     

A heterogeneous catalytic method for the conversion of nitriles into amides using molecular sieves modified with copper(II)

A heterogenous catalytic method is developed for the hydration of nitriles into amides with acetaldoxime. Copper(II) supported on 4 Å molecular sieves is an efficient catalyst for this reaction.     

An efficient InCl3-catalyzed hydration of nitriles to amides: acetaldoxime as an effective water surrogate

An efficient InCl₃-catalyzed hydration protocol of nitriles to amides was developed. The reaction was carried out in toluene at refluxing temperature with the aid of acetaldoxime as an effective water surrogate to produce amides in high yields.     

Efficient Mo(VI)-Catalyzed Hydration of Nitrile with Acetaldoxime

A method for the selective hydration of nitrile to amide by employing commercially available acetaldoxime and inexpensive oxometallate such as molybdate, vanadate, and tungstate in environmentally friendly water is described. Under this protocol, nitriles including aromatic nitriles, heterocyclic nitriles, and aliphatic nitriles were converted into the corresponding amides in good to excellent yields.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Aerobic oxidative transformation of primary azides to nitriles by ruthenium hydroxide catalyst

In the presence of an easily prepared supported ruthenium hydroxide catalyst, Ru(OH)(x)/Al(2)O(3), various kinds of structurally diverse primary azides including benzylic, allylic, and aliphatic ones could be converted into the corresponding nitriles in moderate to high yields (13 examples, 65-94% yields). The gram-scale (1 g) transformation of benzyl azide efficiently proceeded to give benzonitrile (0.7 g, 90% yield) without any decrease in the performance in comparison with the small-scale (0.5 mmol) transformation. The catalysis was truly heterogeneous, and the retrieved catalyst could be reused for the transformation of benzyl azide without an appreciable loss of its high performance. The present transformation of primary azides to nitriles likely proceeds via sequential reactions of imide formation, followed by dehydrogenation (β-elimination) to produce the corresponding nitriles. The Ru(OH)(x)/Al(2)O(3) catalyst could be further employed for synthesis of amides in water through the transformation of primary azides (benzylic and aliphatic ones) to nitriles, followed by sequent hydration of the nitriles formed. Additionally, direct one-pot synthesis from alkyl halides and TBAN(3) (TBA = tetra-n-butylammonium) could be realized with Ru(OH)(x)/Al(2)O(3), giving the corresponding nitriles in moderate to high yields (10 examples, 64-84% yields).     

Polymer‐anchored Ru(II) complex as an efficient catalyst for the synthesis of primary amides from nitriles and of secondary amides from alcohols and amines

A polymer‐anchored ruthenium(II) catalyst was synthesized and characterized. Its catalytic activity was evaluated for the preparation of primary amides from aqueous hydration of nitriles in neutral condition. A range of nitriles were successfully converted to their corresponding amides in good to excellent yields. The catalyst was also effective in the preparation of secondary amides from the coupling of alcohols and amines. The catalyst can be facilely recovered and reused six times without a significant decrease in its activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis and properties of novel dialkylaminocarbenium salts

Novel dialkylaminocarbenium salts with metallocomplex counter ions were prepared by the reaction of phosgene with either DMF or tetramethylurea in the presence of metal chlorides. Reactions of organosilicon amides with phosgene gave corresponding carbenium salts, while organosilicon ureas yielded aminoiminocarbenium salts. Dialkylaminochlorocarbenium salts were reduced with hydrosilanes to give dialkylaminocarbenium, salts and can be easily hydrolyzed to afford either amides or ureas. Pathways of the reaction with water and alcohols depend on the nature of reagent and the reaction conditions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1035–1040, May 1997.     

Transition Metal–Free Sodium Borohydride Promoted Controlled Hydration of Nitriles to Amides

A transition metal–free process, promoted by sodium borohydride, has been developed for convenient and selective hydration of nitriles to corresponding amides. The present process converts the aromatic, aliphatic, and heteroaromatic nitriles with wide functional group tolerance. The regioselective hydration of one nitrile moiety in the presence of an other nitrile group makes high impact in the present protocol.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource: Full experimental and spectral details.]     

Synthesis of alkyl iodides/nitriles from carbonyl compounds using novel ruthenium tris(2,2,6,6-tetramethyl-3,5-heptanedionate) as catalyst

Aldehydes and ketones were hydrogenated to the corresponding alcohols, which were then transformed in situ into their respective iodides and nitriles in good yields. A structurally well-defined O-containing transition metal complex, Ru (TMHD)₃, was found to be the active catalyst for hydrogenation, iodination and cyanation reactions. It has high affinity for the transformation of benzylic alcohols to iodides and nitriles.     

Reaction of nitriles under acidic conditions. Part I. A general method of synthesis of condensed pyrimidines

Nitriles are known to give rise to salts of different compositions with halogen acids. Many of the reactions undergone by nitriles under the influence of halogen acids are, in many cases, assumed to proceed via the intermediate formation of highly reactive imidoyl derivatives. The intermediates produced, in situ, by the reaction of nitriles with hydrogen chloride should, in principle, be capable of reacting with compounds containing appropriately placed nucleophilic and electrophilic centers leading to the formation of a heterocycle incorporating the C=N of the nitrile. Thus, the reaction of aliphatic, aromatic and heterocyclic nitriles with a variety of ortho aminocarbonyl derivatives such as nitriles, amides, esters and ketones of benzene, thiophen, furan, pyrrole, benzothiophene and pyridothiophene have been found to yield the corresponding condensed pyrimidines in fair to good yields. This constitutes a facile and versatile one-pot synthesis of condensed pyrimidines.     

Nickel-Catalyzed Cyanation of 2- and 3- Bromothiophene

Trans-chloro-(2-naphthyl)-bis-(triphenylphosphine)nickel has been used to catalyze the conversion of 2-and 3-bromothiophene with alkali cyanide into the corresponding nitriles. A modified procedure for preparing the catalyst is described.     

Synthesis of novel functional polycyclic chromones through Michael addition and double cyclizations

A base-promoted, microwave-assisted one-pot tandem reaction from simple 3-(1-alkynyl)chromones with 2-halobenzylic nitriles (esters or amides) for the synthesis of novel functional polycyclic chromenones has been developed. This tandem process involves multiple reactions, such as Michael addition and double cyclizations without a transition metal catalyst.     

3 d Transition Metal‐Catalyzed Hydrogenation of Nitriles and Alkynes

Selective hydrogenation of nitriles and alkynes is crucial considering the vast applications of reduced products in industries and in the synthesis of bioactive compounds. Particularly, the late 3d transition metal catalysts (manganese, iron, cobalt, nickel and copper) have shown promising activity for the hydrogenation of nitriles to primary amines, secondary amines and imines. Similarly, semihydrogenation of alkynes to E‐ and Z‐alkenes by 3d metals is adequately successful both via the transfer hydrogenation and by using molecular hydrogen. The emergence of 3d transition metals in the selective synthesis of industrially relevant amines, imines and alkenes makes this protocol more attractive. Herein, we provide a concise overview on the late 3d transition metal‐catalyzed hydrogenation of nitriles to amines and imines as well as semihydrogenation of alkynes to alkenes.     

Combination of Tetrabutylammonium Iodide (TBAI) with tert‐Butyl Hydroperoxide (TBHP): An Efficient Transition‐Metal‐Free System to Construct Various Chemical Bonds

In this account, we describe our recent progress on transition‐metal‐free‐catalyzed cross‐coupling reactions using tetrabutylammonium iodide (TBAI) as the catalyst and tert‐butyl hydroperoxide (TBHP) as the oxidant. A rich variety of important organic compounds including α‐acyloxy ethers, tert‐butyl peresters, allylic esters, amides, α‐amino nitriles, fully substituted pyrazoles, N‐sulfonyl formamidines, α‐amino acid esters, cyanomethyl esters, N‐nitrosamines, and 3‐acyloxy‐2,3‐dihydrobenzofurans have been successfully achieved in high chemoselectivity. Mechanistic studies suggested that TBAI could decompose TBHP to ^tBuO^. and ^tBuOO^. or be oxdized to (hypo)iodite by TBHP.     

Facile and highly selective conversion of nitriles to amides via indirect acid-catalyzed hydration using TFA or AcOH-H2SO4

Both aliphatic and aromatic nitriles are conveniently and selectively converted in a single step, via an indirect acid-catalyzed hydration, into the corresponding amides in 1-8 h using a TFA-H2SO4 mixture as a reagent system. Although the same reagent did not work for the sterically hindered nitriles such as mesitonitrile, the transformation could be accomplished by changing TFA to AcOH at higher temperatures (>90 degrees C).     

Chiral oxazoline substituted optically active poly(m‐phenylene)s: Synthesis and coupling polymerizations of (S)‐4‐benzyl‐2‐(3,5‐dihalidephenyl) oxazoline using transition metal catalysts

Optically active poly(m‐phenylene)s substituted with chiral oxazoline derivatives have been synthesized by the nickel‐catalyzed Yamamoto coupling reaction of optically active (S)‐4‐benzyl‐2‐(3,5‐dihalidephenyl)oxazoline derivatives (X = Br or I). The structures and chiroptical properties of the polymers were characterized by spectroscopic methods and thermal gravimetric analyses. The polymers showed higher absolute optical specific rotation values than their corresponding monomer, and showed a Cotton effect at transition region of conjugated main chain. The optical activities of the polymers should be attributed to the higher order structure such as helical conformations. Moreover, the helical conformation could be induced by addition of metal salts into polymer solutions. The polymers showed good thermal stabilities, which was attributable to the oxazoline side chains. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

In situ Generated Ruthenium Catalyst Systems Bearing Diverse N‐Heterocyclic Carbene Precursors for Atom‐Economic Amide Synthesis from Alcohols and Amines

The transition‐metal‐catalyzed direct synthesis of amides from alcohols and amines is herein demonstrated as a highly environmentally benign and atom‐economic process. Among various catalyst systems, in situ generated N‐heterocyclic carbene (NHC)‐based ruthenium (Ru) halide catalyst systems have been proven to be active for this transformation. However, these existing catalyst systems usually require an additional ligand to achieve satisfactory results. In this work, through extensive screening of a diverse variety of NHC precursors, we discovered an active in situ catalyst system for efficient amide synthesis without any additional ligand. Notably, this catalyst system was found to be insensitive to the electronic effects of the substrates, and various electron‐deficient substrates, which were not highly reactive with our previous catalyst systems, could be employed to afford the corresponding amides efficiently. Furthermore, mechanistic investigations were performed to provide a rationale for the high activity of the optimized catalyst system. NMR‐scale reactions indicated that the rapid formation of a Ru hydride intermediate (signal at δ=?7.8 ppm in the ¹H NMR spectrum) after the addition of the alcohol substrate should be pivotal in establishing the high catalyst activity. Besides, HRMS analysis provided possible structures of the in situ generated catalyst system.     

Synthesis of 2-aryl- and 2-hetaryloxazoles from the oxazolines and oxazolidines

Treatment of 2-phenyl-, 2-(2-furyl)-, and 2-(2-thienyl)oxazolines with nickel peroxide has been found to give, in addition to the dehydrogenation products (2-substituted oxazoles), the fragmentation products (amides of benzoic, furan-2-carboxylic, and thiophen-2-carboxylic acids). This fragmentation appears to give initially the nitriles, which are then converted into the amides by the nickel peroxide. Catalytic dehydrogenation of 2-phenyloxazoline gives low yields of 2-phenyloxazole, the principal product being benzonitrile. Treatment of the Schiff's bases obtained from ethanolamine and aldehydes (benzaldehyde, furfural, and thiophen-2-aldehyde) with nickel peroxide gives trace amounts of the oxazoles, the principal products being the aldehydes, with smaller amounts of the nitriles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 822–825, June, 1986.     

Nmp-based ionic liquids: Recyclable catalysts for both hetero-Michael addition and Knoevenagel condensation in water

A series of novel N-methyl piperidine (Nmp)-based ionic liquids with 1,2-propanediol group are synthesized and used as catalysts for both hetero-Michael addition of α,β-unsaturated amides and Knoevenagel condensation at room temperature in water; and all the examined substrates could be transformed into corresponding products in good to excellent yields. Meanwhile IL-catalyzed hetero-Michael addition of α,β-unsaturated amides in water has not been reported in the previous literatures. Additionally, the catalyst is recyclable for the two reactions. This finding provides a green catalyst for both hetero-Michael addition of α,β-unsaturated amides and Knoevenagel condensation in water.     

Synthesis of α–amino nitriles through Strecker-type reaction using SO3H -functionalized ionic liquid as a homogeneous and water tolerant-acidic catalyst

Task-specific ionic liquid (TSIL) bearing a sulfonic acid group in imidazolium cation (10 mol %), was found to be an effective catalyst for a Strecker-type reaction in water at room temperature. A wide variety of aldehydes/ketones, amines and TMSCN as cyanide source can be easily transformed into the corresponding α-amino nitriles. The water tolerant catalyst could be recycled five times without loss of any activity.