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.     

BASE-CATALYZED CONDENSATION OF BIS(DIETHYLPHOSPHONOMETHYL)-PHOSPHINIC AMIDES WITH ALDEHYDES1

Abstract

The reaction of the mono anion of bis(diethylphosphonomethyl)phosphinic amides (3) with aldehydes gives varying amounts of diethyl alkyl- or arylethenylphosphonates (10) and diethylphosphonomethylalkyl- or arylethenylphosphinic amides (7). When R in 3 is N,N-di-n-propylamino or N-cydohexyl-N-methylamino, the predominate product is 7 and this condensation is a satisfactory synthesis of vinylphosphinic amides which are potential antimetabolites of organic pyrophosphates.     

SOME REACTIONS OF ALIPHATIC AMIDES WITH SULFUR AND SODIUM POLYSULFIDES

Abstract

Some reactions of the aliphatic amides, CH₃CONH₂, CH₃CONHCH₃, CH₃CON(CH₃)₂ and CH₃CON(C₂H₅)₂ with elemental S and sodium sulfides, Na₂S _n , n ≥ 1, have been studied. The initial reaction product with elemental sulfur appears to be a substituted polysulfane, CH₃COS _n NR, formed by the insertion of the sulfur chain into the C[sbnd]N bond. This product decomposes on further heating, forming COS as the major gas product. In solutions of Na₂S _n in the amides, the reactive material appears to be elemental S, present in equilibrium with S _n ^?2. In the N-dialkyl substituted amides, CH₃CON(CH₃)₂ and CH₃CON(C₂H₅)₂, the tetrasulfide is uniquely stabilized by solvent coordination so that solutions of Na₂S₄ in these amides are stable for long periods of time at 130°C.     

REDUCTION OF AZIDES TO AMINES OR AMIDES WITH ZINC AND AMMONIUM CHLORIDE AS REDUCING AGENT

ABSTRACT

Alkyl azides and acyl azides were reduced to the corresponding amines and amides with zinc and ammonium chloride as reducing agent under mild conditions in good to excellent yield.     

KINETIC ENANTIOSELECTIVITY IN THE ALKANESULPHONYL AMIDES FORMATION REACTION

Abstract

In order to obtain quantitative information on the non-bonded interactions in the formation of alkanesulphonyl amides, the kinetics of the reaction between (?)-camphor-10-sulphonyl chloride and (?)- and (+)-1-phenylethylamine (1-PhEtA) in benzene, chlorobenzene, chlorobenzene-nitrobenzene mixtures (1, 4 and 11 v.% of the latter), in a chlorobenzene-o-dichlorobenzene mixture (50v.%) and in o-dichlorobenzene have been studied.     

酰胺水化作用的富里埃红外光谱研究及其SCFPPP计算

本文用富里埃红外光谱仪研究了酰胺水化作用引起的红外光谱变化。用SCFPPP方法对五种酰胺进行了计算。含水酰胺的羰基伸缩振动频率向低波数的位移与酰胺和水分子间的氢键强度成正比。其氢键强度与羰基上氧原子的净电荷密度成正比,与酰胺分子的HOMO轨道能量成反比。     

A NOVEL SYNTHESIS OF ISOXAZOLES VIA 1,3-DIPOLAR CYCLOADDITION OF NITRILE OXIDES TO ACETYL ACETONE

ABSTRACT

Nitrile oxides (2) isolated from the oxidative dehydrogenation of aldoximes (1) by chloramines-T react with acetyl acetone (3) to afford 4-acetyl-3-aryl-5-methyl isoxazoles (5) in good yield. All new compounds were characterized by IR, ¹H NMR, ¹³C NMR, MS studies and elemental analysis.     

SYNTHESIS OF SALICYLTHIOAMIDES AND 4 H-1, 3, 2 BENZOXAZAPHOSPHORIN-DERIVATIVES

Abstract

Recent studies have shown that the dimer of p-methoxyphenylthionophosphinesulfide, 1, is a very superior thiation reagent, as ketones, amides, and esters are in most cases quantitatively converted to their thio-analogues.     

TETRACHLOROPYRIDINE: A NEW REAGENT FOR THE DEHYDRATION OF ALDOXIMES UNDER MICROWAVE*

ABSTRACT

Dehydration of aldoximes to nitriles using tetrachloropyridine under microwave in dry media is described. The procedure is applicable to a variety of aldoximes and the reagent can be recycled and reused.

     

Novel amides and Schiff's bases derived from 1,3,4-oxadiazole derivatives: synthesis and mesomorphic behaviour

The synthesis and liquid crystalline properties of novel achiral amides (Ia–g, IIa–g and IVa,b), achiral Schiff's bases (IIIa–g and Va–g), chiral amides (VI, VII) and chiral Schiff's bases (VIII–XI) incorporating a 1,3,4-oxadiazole ring are reported. All amides of the series I and II display an enantiotropic smectic A phase. The amide IVa,b did not show mesomorphic properties. Amides of the series Ia–g and IIa–g contain a flexible n-tetradecylthio chain, the other terminal substituent is an n-alkoxy chain and n-alkyl chain, respectively (n?=?4–10) and the 1,3,4-oxadiazole is in the terminal rigid core. Amides Ia–g have broader mesomorphic range and higher thermal stability than the corresponding amides IIa–g. Amides IVa,d contain the 1,3,4-oxadiazole ring in the centre of the rigid core and two flexible alkoxy chains as flexible terminal substituents. Thus, the mesomorphic properties are favoured if 1,3,4-oxadiazole is shifted to a terminal position of the rigid core. Schiff's bases IIIa–g display an enantiotropic dimorphism smectic C–smectic A. Schiff's bases IIIa–g have a broader mesomorphic range than the analogous amides Ia–g. Schiff's bases Va–g exhibit a dimorphism smectic A–nematic, and in contrast to this the analogous amide IVa,b did not show mesomorphism. The chiral amides VI and VII and chiral Schiff's bases X and XI did not show mesomorphic properties and only the chiral Schiff's bases VIII and IX display a chiral smectic C phase in a short mesomorphic range. A density functional theory theoretical study at the B3LYP/6–311++G(d,p) level was performed in order to analyse the structural features that must be related with the mesomorphic behaviour of the reported compounds.     

SOCl2/β-Cyclodextrin: A New and Efficient Catalytic System for Beckmann Rearrangement and Dehydration of Aldoximes Under Aqueous Condition

A rapid and efficient synthesis of amides via Beckmann rearrangement of ketoximes and dehydration of aldoximes to corresponding nitriles with good to excellent yields has been carried out in the presence of SOCl₂/β-cyclodextrin under aqueous conditions. The β-cyclodextrin has been recovered and reused.     

Copper catalyzed aryl amidation between Nα-Fmoc-protected amino-acid azides and aryl boronic acids

Abstract

A simple and efficient method for the synthesis of aryl amides via oxidative copper-catalyzed coupling of commercially available aryl boronic acids and bench stable N^α-protected amino-acid azides is reported. The potential utility of this protocol is demonstrated through a survey of diversely substituted aryl boronic acids and several side-chain functionalized amino-acid azides, leading to the preparation of the desired amidated products in good to excellent yields. This amide synthesis is suitable for the preparation of amides (such as peptide aryl amides and sterically hindered amino acids) that are not or hardly accessible via classical approaches.     

Synthesis of pyrazolopyrimidinones as sildenafil derivatives and sclerotigenin

A series of novel pyrazolo pyrimidinone derivatives (3(a–d), 4(a–d), and 6(a–d)) was synthesized from various pyrazolo amides (2a–d) which are synthesized by the reaction between ethyl 5-amino-3-methyl-1-phenyl-1H-pyrazole-4-carboxylate (1) and various lithium amides. In addition, we also described the synthesis of sclerotigenin drug molecule which has quinazoline moiety from simple 2-nitro benzoic acid with high yields.     

Simple and Highly Efficient Procedure for Conversion of Aldoximes to Nitriles Using N-(p-Toluenesulfonyl) Imidazole

A facile and efficient method for dehydration of aldoximes into nitriles using N-(p-toluenesulfonyl) imidazole (TsIm) is described. In this method, aldoximes were refluxed with TsIm in the presence of 1,8-diazabicyclo-[5.4.0]undec-7-ene (DBU) in dimethylformamide (DMF) to afford the corresponding nitriles in good yields. This methodology is highly efficient for various structurally diverse aldoximes including aromatic, heteroaromatic, and aliphatic oximes. A plausible mechanism for the conversion of aldoxime into nitriles using TsIm/DBU is explained.     

CATALYTIC DEHYDROCOUPLING OF AMINE-BORANE ADDUCTS TO FORM AMINOBORANES AND BORAZINES

A mild, catalytic dehydrocoupling route to aminoboranes and borazine derivatives from either primary or secondary amine-borane adducts has been developed using late transition metal complexes as precatalysts. The dehydrocoupling of Me ₂ NH·BH ₃ was found to be catalyzed by 0.5 mol% [Rh(1,5-cod)(μ-Cl)] ₂ in solution at 25°C to give [Me ₂ N─BH ₂ ] ₂ (1) quantitatively after ca. 8 h. This new catalytic method was extended to other secondary adducts RR ′NH·BH ₃ which afforded the dimeric [(1,4-C ₄ H ₈ )N─BH ₂ ] ₂ (2) and [PhCH ₂ (Me)N─BH ₂ ] ₂ (3) or the monomeric aminoborane ⁱ Pr ₂ N═BH ₂ (4) under mild conditions. The catalytic dehydrocoupling of NH ₃ ·BH ₃ , MeNH ₂ ·BH ₃ , and PhNH ₂ ·BH ₃ at 45°C affords the borazine derivatives [RN─BH] ₃ (5: R = H; 6: R = Me; 7:R = Ph). TEM analysis of the contents of the reaction solution for the [Rh(1,5-cod)(μ-Cl)] ₂ catalyzed dehydrocoupling of Me ₂ NH·BH ₃ together with Hg poisoning experiments suggested a soluble heterogeneous catalyst involving Rh(0) nanoclusters.     

Stannous Chloride Reduction of Nitroalkenes in Amines. Synthesis and Cycloaddition of α-Dialkylaminoaldoxime

α-Dialkylamino aldoximes 12 were prepared by stannous chloride reduction of nitroalkenes in amines. An intramolecular Michael addition-deoxygenation mechanism is suggested. α-Allylamino aldoxime underwent an efficient Intramolecular Oxime Olefin Cycloaddition (IOOC) giving 13     

Synthesis of oximes,conversion to nitrile oxides and their subsequent 1,3-dipolar cycloaddition reactions under microwave irradiation and solvent-free reaction conditions

Aldoximes and ketoximes were readily synthesized from aldehydes and hydroxylamine hydrochloride on Al₂O₃ without solvent under microwave irradiation. At higher irradiation power, aldoximes dehydrated to nitriles and ketoximes rearranged to amides. Aldoximes reacted in a one-pot reaction with N-chlorosuccinimide and alkenes or alkynes over alumina under microwave irradiation to give isoxazolines or isoxazoles. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:351–354, 1998     

Sydnone Ring as an ortho-Director of Lithiation, 3: One-Pot Regiospecific o-Acylation and Subsequent Sydnone 4-Substitution

Readily available 3-phenylsydnone (1) reacts with n-butyllithium/N,N,N′,N′-tetramethylethylenediamine (TMEDA) to form the dilithio species 2, which can be acylated regiospecifically at the ortho-aryl position using N-methoxy-N-methylamides (Weinreb's amides) followed by reaction with a second, more reactive electrophile at the sydnone C-4 position. Asymmetrically substituted arylsydnones 7 are obtained in 57–86% yield.     

ALKYLATIOIM,ACYLATION, AND ARYLATION PRODUCTS OF 1-CYANO-ISOTHIOCHROMANE

Abstract

1-Cyano-isothiochromane (1a) can be alkylated in position 1, using the carbanion that is formed from sodium amide, sodium hydride, or n-butyllithium. With methyl iodide or ethyl iodide 1c and 1d are formed; with α-halogenated ether or thioether, 1e and 1f; with propargyl bromide, 1h; with bromo acetophenone, li; and with ethyl chloroacetate, 1k. Similarly, acylation with benzoyl chloride leads to 11, and with 2,4-dinitrofluorobenzene to 1m. The alkylation products of 1a can be oxidized with peracids to the sulfones 2 and with LiAlH₄ reduced to 1-aminomethyl-isothiochroman (3): Acid hydrolysis of 1 gave isothiochromane-1-carboxylic acids, 4, whereas when 1 is treated with hydrogen peroxide in alkaline medium the S-dioxide and the S-oxide acid amides, 5 and 6 respectively, are formed.     

PCC-Promoted Dehydration of Aldoximes: A Convenient Access to Aromatic,Heteroaromatic, and Aliphatic Nitriles

A simple and convenient procedure for the synthesis of nitriles by dehydration of aldoximes using a PCC (pyridiniumchlorochromate) has been developed. A variety of aromatic, heteroaromatic, and aliphatic aldoximes are converted.

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