Synthesis of enantiopure β-amino amides via a practical reductive amination of the corresponding β-keto amides

A convenient and efficient reductive amination for the preparation of chiral β-amino amides is developed utilizing microwave heating. A variety of chiral β-keto amides react with ammonium acetate and sodium cyanoborohydride to afford the desired functionalized amines in good yields. This improved procedure takes advantage of microwave heating to significantly accelerate the reaction and offers a convenient and effective method to access some interesting molecules containing primary amine functionalities.     

Microwave assisted, palladium catalyzed aminocarbonylations of heteroaromatic bromides using solid Mo(CO)6 as the carbon monoxide source

The direct conversion of a variety of heteroaromatic bromides into heteroaromatic amides is described. This reaction utilizes Mo(CO)₆ as the carbon monoxide source and is performed using microwave heating allowing for very short reaction times. This convenient methodology allows for the preparation of a variety of heteroaromatic amides useful in medicinal chemistry applications.     

Direct, facile synthesis of N-acyl-alpha-amino amides from alpha-keto esters and ammonia

N-Acyl-alpha-amino amides were prepared, without the necessity of chromatographic purification, in a single step by heating the corresponding alpha-keto ester in methanolic ammonia.     

Cascade synthesis with (triphenylphosphoranylidene)-ethenone as a versatile reagent for fast synthesis of heterocycles and unsaturated amides under microwave dielectric heating

A general procedure for the synthesis of a large variety of compounds comprising an alpha, beta,-unsaturated carbonyl functionality was developed. The use of one-pot cascade synthesis with (triphenylphosphora-nylidene)ethenone as a versatile reagent for various formations including heterocycles of different ring sizes and unsaturated amides in combination with microwave dielectric heating is described. The method was used to synthesize a small library of unsaturated amides.     

The use of formamidine protection for the derivatization of aminobenzoic acids

N,N-Dimethylformamidine and novel N,N-diisopropylformamidine protecting groups were used to carry out a one-pot conversion of aminobenzoic acids into the corresponding amides. General conditions for an in situ transformation of aminobenzoic acids and their heterocyclic analogues into the corresponding formamidine-protected acid chlorides were developed. These chlorides were used in reactions with amines, including poorly reactive anilines. The protected amides were then smoothly deprotected by heating with ethylenediamine derivatives, resulting in a general procedure for the one-pot transformation of aminobenzoic acids into their amides. Our one-pot procedure was successfully applied to the preparation of several compounds of pharmaceutical interest.     

Halo substituent effects on intramolecular cycloadditions involving furanyl amides

Intramolecular Diels-Alder reactions involving a series of N-alkenyl-substituted furanyl amides were investigated. Stable functionalized oxanorbornenes were formed in high yield upon heating at 80-110 degrees C. The cycloaddition reactions include several bromo-substituted furanyl amides, and these systems were found to proceed at a much faster rate and in higher yield than without substitution. This effect was observed by incorporating a halogen in the 3- or 5-position of the furan ring and appears to be general. The origin of increased cycloaddition rates for halo-substituted furans has been investigated with quantum mechanical calculations. The success of these reactions is attributed to increases in reaction exothermicities; this both decreases activation enthalpies and increases barriers to retrocycloadditions. Halogen substitution on furan increases reactant energy and stabilizes the product, which is attributed to the preference of electronegative halogens to be attached to a more highly alkylated and therefore more electropositive framework.     

Poly[amino-p-(hydroquinone or benzoquinone)]amides and poly(p-benzoquinono)diimidazoles of phenylene dicarboxylic acids. IV

Poly(amino-p-benzoquinone)amides were indirectly prepared by low-temperature polycondensation of 2,3,5,6-tetraamino-p-hydroquinone, with terephthaloyl, isophthaloyl, or phthaloyl dichloride and subsequent oxidation of the obtained poly(amino-p-hydroquinone)amides. Then the poly(amino-p-benzoquinone)amides were converted by cyclodehydration with heating to the corresponding poly(p-benzoquinono)diimidazoles. The prepared redox thermally stable polymers were characterized by elemental analysis, UV, and IR spectral study, inherent viscosity solubility, and thermal analysis (DSC, TGA). The synthesis and properties of the corresponding model compounds are also reported.     

Microwave-assisted polymer-supported acylation of 15-membered azalides—a rapid and efficient procedure

The application of microwave heating to a polymer-assisted solution phase synthesis technique has been used to develop a rapid and efficient protocol for the solution phase synthesis of amides from unprotected polyfunctional 15-membered azalides.     

Isolation and characterization of 2-alkylaminobenzo[b]furans. Evidence for competing O-arylation in Cu-catalyzed intramolecular amidation

2-Alkylaminobenzo[b]furans were isolated and characterized by X-ray crystal structural analysis, for the first time, from the Cu-catalyzed intramolecular amidation of hindered secondary amides under controlled microwave heating. A mechanism was proposed to account for competing Cu-catalyzed intramolecular N- and O-arylation pathways, which were controlled by the bulkiness of substituents on the nitrogen atom of secondary amides.     

N-Alkylation of N-trimethylsilyl derivatives of lactams,amides, and imides with alkyl sulfonates

Russian Chemical Bulletin - The reaction of N-trimethylsilyl derivatives of amides and imides with alkyl sulfonates on heating affords the corresponding N-alkyl derivatives and trimethylsilyl...     

A convenient highly stereoselective synthesis of allyl amides from Baylis–Hillman adducts using Amberlyst-15 as a heterogeneous reusable catalyst

The Baylis–Hillman adducts have efficiently been converted into the corresponding allyl amides in stereoselective manner by heating in acetonitrile under reflux in the presence of Amberlyst-15 as a catalyst. The catalyst works under heterogeneous conditions and can be recycled.     

Iodine-catalyzed one-pot synthesis of amides from nitriles via Ritter reaction

Ritter reactions of alcohols and tert-butyl acetate with various nitriles were performed using iodine as a mild and effective catalyst under heating conditions to afford the corresponding amides in good to excellent yields.     

1,2,4-Oxadiazoles. XI. An intermediate in the isomerization from nitrones to amides

Certain 1,2,4-oxadiazolyl-aryl nitrones isomerize to the corresponding amides by heating in ethanol via stable intermediates, for which the structure of 1,2,4-oxadiazolium inner salts was recognized.     

Thionation of amides using a solid-supported P2S5 reagent under microwave irradiation

In this Letter, we describe an improved method for the thionation of amides. Using a solid-supported P₂S₅ reagent, heating under microwave irradiation furnished thioamides in good to excellent yields, with a significantly reduced reaction time compared with that achieved under conventional heating. Furthermore, a change of solvent from that described in the literature enabled a simplified work-up and purification of the products.     

Microwave-assisted synthesis utilizing supported reagents: a rapid and efficient acylation procedure

[reaction: see text] The application of microwave heating to a polymer-assisted solution-phase (PASP) synthesis technique has been utilized to develop a rapid and efficient protocol for the solution-phase synthesis of amides from either amine or carboxylic acid cores.     

A rapid thermal cyclisation of ethane-1,2-bis-fatty amides and alcohol derivatives to Δ2-imidazolines with phenylphosphorodiamidate.

Brief heating of ethane-1,2-bis-fatty amides at 235 – 250° with phenylphosphorodiamidate gave high yields of 2-fattyalkyl-Δ²-imidazolines.     

A novel synthesis of benzo- and indolo[a]quinolizidines by intramolecular diels-alder reaction of l-azadienes

Intramolecular Diels-Alder reaction of l-azadienes was conducted by heating the α,β-unsaturated amides (2a ～ d and 6) in the presence of trimethyl- chlorosilane, triethylamine and zinc chloride to give benzo- and indolo[a]- quinolizidines (5a ～ e and 7).     

Neat reaction of carboxylic acid methyl esters and amines for efficient parallel synthesis of scaffold amide libraries

Efficient synthesis of unsubstituted and substituted amides is described. The reaction is characterised by its mildness and ease of work-up. A library of amides, synthesised by heating ester 1 or 2 with various amines has been generated. To cite this article: F. Machetti et al., C. R. Chimie 6 (2003).     

Solventless lactam synthesis by intramolecular cyclizations of alpha-iminoester derivatives under microwave irradiation

We have previously reported a new synthesis of amides from esters and amines under microwave irradiation, offering much higher yields than those achieved with conventional heating [1]. We have now extended these studies to the ring closure of neat iminoesters I2, I3 and I4-I6 to give five- and six-membered ring lactams L5, L6 and larger lactams L7-L9 (where I means imine and L means lactam), respectively, under both classical heating conditions and microwave irradiation.     

SYNTHESIS OF AMIDES FROM ESTERS AND AMINES UNDER MICROWAVE IRRADIATION

ABSTRACT

Formamide, primary and secondary amines react with esters in the presence of potassium tert-butoxide under microwave irradiation. Substituted amides are formed in yields (generally more than 70%) much higher than under conventional heating.