An efficient Pd-catalyzed hydration of nitrile with acetaldoxime

An efficient palladium-catalyzed protocol for the hydration of nitrile to amide with acetaldoxime has been developed. A plausible mechanism was suggested involving the first Pd(II)-catalyzed nitrile-oxime coupling and the following disruption of the intermediate into amide and acetonitrile in a concerted manner.     

FeCl3-catalyzed Ritter reaction. Synthesis of amides

A safe and inexpensive synthesis of amides, from benzylic alcohols and nitriles and from t-butyl acetate and nitriles, using a Ritter reaction catalyzed by FeCl₃·6H₂O is described.     

InCl3-catalyzed efficient synthesis of spiro-perimidine derivatives

InCl₃ was found to be a mild and effective catalyst for the simple and efficient synthesis of spiro-perimidine derivatives by the reaction of naphthalene-1,8-diamine and active carbonyl compounds in water at room temperature. This protocol includes some important aspects like the use of water as a “green” reaction medium, good yielding of products and mild reaction conditions.     

An efficient synthesis of diarylmethanes via InCl3·4H2O-catalyzed dehydration of electron-rich arenes with trioxane

A facile, efficient and environmentally benign procedure for the synthesis of diarylmethanes via the reaction of arenes with trioxane catalyzed by InCl₃·4H₂O was developed. The reactions of aromatic compounds bearing electron-donating group proceeded smoothly affording the corresponding diarylmethanes in good to excellent yields.     

An efficient synthesis of Baylis-Hillman adducts of acrylamide: Pd-catalyzed hydration of Baylis-Hillman adducts of acrylonitrile

An efficient palladium-catalyzed two-step protocol for the synthesis of Baylis-Hillman adducts of acrylamide was developed. The method involved the preparation of Baylis-Hillman adducts of acrylonitrile and a Pd-catalyzed hydration of nitrile with acetaldoxime.     

InCl3-assisted one-pot synthesis of 1-aminocarbazoles

A novel InCl₃-mediated one-pot reaction leading to 1-aminocarbazoles is reported. Starting from easily available 2-acetyl-1H-indole, the reaction involves the alkylation of C-3 with a prop-2-yn-1-ol followed by a domino aminobenzannulation reaction in the presence of a secondary amine. The indium salt is most likely involved as catalyst in all three steps of the one-pot reaction. Starting from 2-acetyl-1H-indole and a series of prop-2-yn-1-ols and secondary amines a small library of products has been obtained.     

InCl3-catalyzed reaction of aromatic amines with cyclic hemiacetals in water: facile synthesis 1,2,3,4-tetrahydroquinoline derivatives

By using a domino reaction of aromatic amines with various cyclic hemiacetals catalyzed by indium chloride in water, tetrahydroquinoline derivatives were synthesized efficiently.     

InCl3 catalyzed C-C coupling of aryl alcohols and TosMIC

The InCl₃ mediated C-C coupling reaction between aryl alcohols and TosMIC gives the corresponding amides in good to high yields.     

InCl3-catalyzed efficient one-pot synthesis of 2-pyrrolo-3′-yloxindoles

An InCl₃-catalyzed one-pot synthesis of 2-pyrrolo-3′-yloxindoles was achieved via three-component reaction of 3-phenacylideneoxindole, β-keto ester, and ammonium acetate at reflux by a sequential Michael addition followed by Paal-Knorr condensation.     

The catalytic hydration of nitriles to amides using a homogeneous platinum phosphinito catalyst

New homogeneous catalysts for the hydration of nitriles to amides are described. The catalyst precursors are coordination compounds of Pt(II) with secondary phosphine oxides. They contain a hydrogen bridged mono-anionic didentate phosphinito group, together with a third phosphine oxide ligand and a monodentate anionic ligand, either hydride or chloride. Reacting the chloride with silver ion, or the hydride with water gives a cationic species which is the active catalyst. On coordination to the cation the nitrile becomes susceptible to nucleophilic attack. The hydrolysis gives the amide as the sole product, and there is no tendency towards further hydrolysis to the acid. The effects of substituents on phosphorus are investigated, and a reaction mechanism is suggested. The most active catalyst, [PtH(PMe₂OH)(PMe₂O)₂H], 2a, is derived from dimethylphosphine oxide, and this precursor catalyses the hydration of acrylonitrile to acrylamide with a turnover number of 77,000, without addition to the C=C double bond.     

An eco-friendly synthesis of 2-aminochromenes and indolyl chromenes catalyzed by InCl3 in aqueous media

A simple and convenient method for the synthesis of new 2-aminochromenes and indolyl chromenes via an indium trichloride catalyzed, three-component reaction in aqueous media is described.     

InCl3-catalyzed three-component reaction: a novel synthesis of dihydropyrano[3,2-b]chromenediones under solvent-free conditions

Three-component coupling (3CC) of kojic acid, aldehyde and 1,3-dione has been achieved in the presence of 10 mol % InCl₃ under solvent-free conditions to afford the corresponding dihydropyrano[3,2-b]chromenedione derivatives in good yields. This is the first example of the condensation of kojic acid, aldehyde and 1,3-diones to provide a novel series of kojic acid derivatives.     

Microwave-assisted InCl3-catalyzed Meyer-Schuster rearrangement of propargylic aryl carbinols in aqueous media: a green approach to α,β-unsaturated carbonyl compounds

A novel, efficient, simple and environmentally benign protocol for the Meyer-Schuster isomerization of propargylic aryl carbinols into α,β-unsaturated carbonyl compounds has been developed using catalytic amounts of InCl₃, pure water as the solvent, and microwave irradiation as the heating source.     

Ac2O/K2CO3/DMSO: an efficient and practical reagent system for the synthesis of nitriles from aldoximes

The transformation of aldoximes to nitriles using acetic anhydride as dehydration agent under mild reaction conditions is reported. The reaction, which proceeds under weak alkaline condition, allows for the conversion of a range of aldoximes including aromatic aldoximes, alphatic aldoximes, and heterocyclic aldoximes in good to excellent yields. This method has also been successfully applied to the synthesis of calcium channel blocker nilvadipine in pilot scale.     

Selective reductive cleavage of 2,3-epoxybromides by the InCl3-NaBH4 reagent system

A combination of sodium borohydride and a catalytic amount of indium(III) chloride in acetonitrile reduces 2,3-epoxybromides to the corresponding allylic alcohols in good yields involving reduction of the bromo moiety followed by selective C-O bond cleavage through a radical process. Several aromatic, cyclic and open-chain bromoepoxides successfully participated in this reaction.     

InCl3-CH3CN-H2O: an efficient catalyst-solvent combination for the synthesis of Perlin aldehydes and related compounds. Application in the synthesis of unnatural l-azasugars

InCl₃-CH₃CN-H₂O has been found to be an efficient catalyst-solvent combination for the synthesis of Perlin aldehydes and related compounds. While acetylated glycals afforded the Perlin aldehydes directly with InCl₃ and water, benzylated glycals on the other hand provided the hemiacetals under identical condition. The methodology reports a non-mercurial approach to Perlin aldehydes. Noteworthy is that this reaction is more facile as well as highly selective with glycals possessing a hydroxyl as a leaving group than with a benzyloxy group. Extension of this reaction to 2-C-hydroxymethyl glycals resulted in the formation of the corresponding hemiacetals, which were further transformed in to unsaturated azasugars with an exo-methylene group at C-2 position. Glycosidase inhibition studies reveal that these compounds display selectivity in inhibiting glucosidases rather than galactosidases.     

An improved protocol for synthesis of N-arylamides and benzoxazoles by the copper-catalyzed reaction of aryl halides with nitriles

An improved protocol for the synthesis of N-arylamides and benzoxazoles by the copper-catalyzed reaction of aryl halides with nitriles has been developed. Use of acetaldoxime as the hydrolysis reagent instead of H₂O facilitates the operation of the reaction. The significantly decreased amount of nitriles, along with use of weak base K₂CO₃ instead of strong base KOH, makes this transformation atom-efficient and environmentally benign. A variety of N-arylamides and benzoxazole derivatives can be synthesized according to this approach.     

Efficient and selective hydration of nitriles to amides in aqueous systems with Ru(II)-phosphaurotropine catalysts

A simple and efficient synthesis of amides by selective hydration of aromatic and aliphatic nitriles is described. The catalysts are prepared in situ from easily available Ru-precursors and ligands using water as the solvent. The most active catalyst, is obtained from [RuCl₂(dmso)₄] and benzylated 1,3,5-triaza-7-phosphaadamantane. Of the 16 substrates examined, 92–99% conversions of 14 nitriles were achieved in one hour at reflux temperature.     

Synthesis of some novel functionalized dihydropyrido[2,3-d]pyrimidines via an one-pot three-component reaction catalysed by InCl3

Some novel functionalized dihydropyrido[2,3-d]pyrimidine derivatives 4 were synthesized using a one-pot three-component reaction of 6-aminouracils 1, aryl aldehydes 2 and 3-cyanoacetyl indole 3 using InCl₃ as catalyst.     

An efficient catalytic method for the Beckmann rearrangement of ketoximes to amides and aldoximes to nitriles mediated by propylphosphonic anhydride (T3P®)

An efficient method for the Beckmann rearrangement of ketoximes to amides mediated by a catalytic amount (15 mol %) of propylphosphonic anhydride (T3P®) is described. Aldoximes underwent second order Beckmann rearrangement to provide the corresponding nitriles in excellent yields on reacting with T3P (15 mol %) at room temperature. The main advantages of this environmentally friendly protocol include procedural simplicity, and particularly ease of isolation of the products.