Synthesis of amides through the Cannizzaro-type reaction catalyzed by lanthanide chlorides

Amidation of aldehydes with lithium amides through the LnCl₃-catalyzed Cannizzaro-type reactions afforded a variety of amides in high yields. The electronic and steric effects on the reaction were investigated. The features of the economical catalysts, high yields, tolerance of a wide range of lithium amides and aromatic aldehydes make this methodology an easy and valid contribution to the direct synthesis of amides from aldehydes.     

Simple Lanthanide Amides [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 as Highly Efficient Catalysts for the Nitroaldol Reaction

This contribution is to report the application of simple lanthanide amides [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 exhibiting a high activity toward catalyzing Henry reaction of aromatic aldehydes with nitroalkanes to give β-nitroalcohols or β-nitroolefins with a very good chemoselectivity by controlling the reaction temperatures and by selecting aromatic aldehydes. It was found that this catalytic system was compatible with a wide range of substrates of aldehydes.     

nBu4NI-catalyzed oxidative amidation of aldehydes with tertiary amines

An efficient oxidative coupling protocol for amide formation has been developed. Various tertiary amines and aromatic aldehydes were oxidized to their corresponding tertiary amides in moderate to good yields in the presence of a simple nBu₄NI-catalyst.     

Characterization,Consideration and Catalytic Application of Novel Pyrazine‐1,4‐Diium Trifluoromethanesulfonate {[1,4‐DHPyrazine](OTf)2} as a Green and Recyclable Ionic Liquid Catalyst in the Synthesis of Amidoalkyl Naphthol Derivatives

An efficient and green one‐pot method has been developed for the synthesis of amidoalkyl naphthol derivatives using reusable {[1,4‐DHPyrazine](OTf)₂} as an ionic liquid catalyst via condensation of aromatic aldehydes, β‐naphthol and various amides under solvent‐free conditions.     

Oxidation of aldimines to amides by m-CPBA and BF3·OEt2

Several amides were obtained in high yields by an efficient method from the corresponding imines which are readily prepared from aldehydes. This procedure involves the oxidation of aldimines with m-CPBA and BF₃·OEt₂. In this reaction, the product is strongly influenced by the electron releasing capacity of the aromatic substituent.     

New C(4)‐Functionalized Colchicine Derivatives by a Versatile Multicomponent Electrophilic Aromatic Substitution

Electrophilic alkylation of colchicine at C(4) was accomplished by a multicomponent aromatic electrophilic substitution reaction with electrophilic aldehydes and carboxylic acids or amides in H₂SO₄. A series of new derivatives were obtained and evaluated for their antiproliferative effect towards various tumor cell lines, and their stimulatory effect on the development of polarity in human neutrophils.     

The catalytic decomposition of secondary carboxamides by transition-metal complexes

High-boiling secondary amides of monocarboxylic acids decompose under the influence of RhCl(PPh₃)₃, HRhCl₂(PPh₃)₃, and some other organometallic catalysts in homogeneous phases into nitriles and carbinols. The latter are further transformed into aldehydes and hydrocarbons. N-Benzyl-(and N-substituted benzyl-) aromatic amides from nitriles generated both from the aroyl and the benzyl moieties. Amides carrying Cl, Br or I atoms in the aromatic ring are partially or completely dehalogenated during the catalysis. Malonamides are decarbonylated and form acetamides.Both mono- and di-amides give amido-complexes with the catalysis employed. The complexes derived from RhCl(PPh₃)₃ are extremely labile, while those from RuCl₂(PPh₃)₃ can be isolated.     

Sulphamic Acid （H2NSO3H）-Catalyzed Multicomponent Reaction of β-Naphthol： An Expeditious Synthesis of Amidoalkyl Naphthols

Sulphamic acid （H2NSO3H） was found to be an efficient catalyst for the multicomponent condensation reaction of β-naphthol, aromatic aldehydes and urea or amides to afford the corresponding α-amidoalkyl-β-naphthols in good yields. The remarkable features of this new procedure are high conversions, short reaction time, clean reaction profiles and simple experimental and work-up procedures.     

Haloarenes in the Duff reaction under high pressures

Reactions of haloarenes with urotropine in CF₃COOH at elevated temperatures and high pressures give the corresponding aromatic aldehydes and/orN-(haloarylmethyl)trifluoroacetamides. The yeilds of the products and their ratio depend on electronic properties of substituents in the aromatic ring. The reaction carried out in a mixture of CF₃COOH and (CF₃CO)₂O affords only amides.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2221–2224, November, 1995.     

H3Mo12O40P-Catalyzed One-Pot Synthesis of Amidoalkyl Naphthols

Solid H₃Mo₁₂O₄₀P is used for an efficient one-pot synthesis of amidoalkyl naphthols using aromatic aldehydes, β-naphthol, and urea or amides in carbon tetrachloride. The catalyst was efficiently recovered from the reaction mixture and reused with negligible loss of catalyst activity. Ambient conditions, simple workup, and good yield are some of the striking features of the present protocol.     

Tetrakis(acetonitrile)copper(I) Hexafluorophosphate–Promoted Efficient Synthesis of Amidoalkyl Naphthols Under Solvent-Free Conditions

An efficient and direct protocol for the preparation of amidoalkyl naphthols employing a multicomponent, one-pot condensation reaction of β-naphthol, aromatic aldehydes, and amides (acetamide, benzamide, and urea) in the presence of tetrakis(acetonitrile)copper(I) hexafluorophosphate [Cu(CH₃CN)₄PF₆] under solvent-free conditions at 80 °C is described. Good yields, short reaction time, and easy workup are advantages of this procedure.     

Sterically oriented synthesis and structure of new perphosphorylated resorcinarenes

Tetraarylresorcinarenes in a chair conformation of C_2h symmetry were synthesized by sterically oriented condensation of aromatic aldehydes with resorcinol and 2-methylresorcinol. By further phosphorylation of resorcinarenes with phosphorous amides perphosphorylated derivatives were obtained with rctt configuration of substituents at internuclear methylidene bridges. Structure of these compounds was proved using NMR spectroscopy and X-ray diffraction analysis.     

Tandem three-component reaction of aldehyde, alkyl acrylate, and amide using ethyl diphenylphosphine as organocatalyst

It is the first time that a chemoselective EtPPh₂-catalyzed three-component reaction of aromatic aldehyde, alkyl acrylate, and phthalimide or methyl toluenesulfonamide has been achieved. A variety of highly functional adducts can be generated efficiently in one step within 1-72 h in 38-93% yields. The reaction mechanism is proposed to undergo Morita-Baylis-Hillman reactions of aryl-substituted aldehydes and alkyl acrylates followed by Michael additions of amides. Our studies indicated that, in combination of EtPPh₂, alkyl acrylate also catalyzed this process.     

Selective and facile synthesis of α,β-unsaturated nitriles and amides with N-hydroxyphthalimide as the nitrogen source

The direct conversion of α,β-unsaturated aldehydes to corresponding nitriles promoted by Pd(OAc)₂ and phthalic acid which was hydrolyzed from N-hydroxyphthalimide (NHPI) has been disclosed. Additionally, it was found that when water was used as the solvent, α,β-unsaturated amides was obtained as the main products in good to excellent yields. It was first reported that NHPI was utilized as the nitrogen source to synthesize α,β-unsaturated nitriles and amides from aldehydes. Control experiment demonstrated that aldehydes undergo a process of oximation and dehydration to form nitriles and amides.     

A mild titanium-based system for the reduction of amides to aldehydes

A mild method for the reduction of amides to aldehydes using 1,1,3,3-tetramethyldisiloxane/titanium(IV) isopropoxide reducing system is described. The reaction occurs under mild conditions and allows the reduction of aromatic as well as aliphatic, tertiary amides to the corresponding aldehydes, in good yields. This methodology was extended to the reduction of aromatic secondary and primary amides to the corresponding aldehydes.     

l-Proline amides catalyze direct asymmetric aldol reactions of aldehydes with methylthioacetone and fluoroacetone

Direct aldol reactions of aldehydes with methylthio- and fluoroacetone catalyzed by proline amides have been investigated. l-Prolinamide 5e was found to be the best catalyst. Under the optimized reaction conditions, a series of aromatic and aliphatic aldehydes reacted smoothly with methylthioacetone, to generate 1-methylthio-4-hydroxyketones 3 in good yields and with high regio- and enantioselectivities. Excellent enantioselectivities of up to 98% ee were observed for aromatic aldehydes and even higher enantioselectivities of >99% ee were observed for aliphatic aldehydes. Asymmetric direct aldol reactions of fluoroacetone with aldehydes in the presence of 20 mol % of 5e preferentially occurred at the fluoromethyl group, yielding products with high enantioselectivities (up to 98% ee).     

Synthesis of functional derivatives of aryl trichlorovinyl (trichloroallyl) ketones via consecutive transformations of the carbonyl group

An efficient procedure have been developed for the selective reduction of the carbonyl group in phenyl trichlorovinyl ketone and aryl trichloroallyl ketones by the action of NaBH₄ in propan-2-ol to obtain the corresponding alcohols. The hydroxy group in the latter was converted into amino by the Ritter reaction. Treatment of the alcohols and amines with 5-phenylisoxazole-3-carbonyl chloride and 4,5-dichloroisothiazole-3-carbonyl chloride gave the corresponding esters and amides, and condensation of the amines with aromatic aldehydes afforded Schiff bases.     

Metal-free one-pot oxidative conversion of benzylic alcohols and benzylic halides into aromatic amides with molecular iodine in aq ammonia, and hydrogen peroxide

Various primary alcohols, particularly benzylic alcohols, could be converted into the corresponding aromatic amides in good yields in a one-pot manner by treatment with molecular iodine in aq. NH₃, followed by reaction with ∼30% aq H₂O₂. Similarly, various benzylic halides could be also converted into the corresponding aromatic amides in good yields in a one-pot manner by treatment with molecular iodine in aq NH₃, followed by reaction with ∼30% aq H₂O₂. The present reactions involve the metal-free one-pot oxidative conversion of benzylic alcohols and benzylic halides into the corresponding aromatic amides, respectively.     

One-pot stibine modified Co2(CO)8 catalyzed reductive N-alkylation of primary amides with carbonyl compounds

A one-pot stibine modified Co₂(CO)₈ homogeneous catalytic reductive N-alkylation of primary amides using aldehydes/ketones as alkylating agents, is reported. Good to excellent yields of a wide range of secondary amides are obtained (up to 97%) under relative mild conditions.     

Rhodium‐catalyzed ortho‐C‐H olefination of aromatic aldehydes employing transient directing strategy

A Rhodium(III)‐catalyzed ortho‐C‐H olefination of aromatic aldehydes in the presence of catalytic amount of TsNH₂ has been developed. The in situ generated imine intermediate from aldehyde and TsNH₂ worked as a transient directing group. Both electron‐rich and electron‐deficient aromatic aldehydes were tolerated, affording the corresponding products in moderate to good yields. Importantly, the present protocol provides a straightforward access to olefinated aromatic aldehydes with aldehydes as the simple starting materials.