Palladium-catalyzed aminocarbonylation of aryl iodides using aqueous ammonia

Aminocarbonylation of aromatic iodides using aqueous ammonia in toluene has been developed. Various primary aromatic amides have been efficiently synthesized in good to excellent yields in the presence of catalytic quantities of Pd(OAc)₂/CYTOP®292. The usage of aqueous ammonia avoids the handling of two gases in the reaction.     

Convenient synthesis of C-terminal di- and tri-peptide amides from N-protected dipeptidoylbenzotriazoles

N-Protected dipeptidoylbenzotriazoles react with aqueous ammonia to give dipeptide primary amides (77-98%) and with N-unprotected α-amino amides to afford tripeptide primary amides (82-86%).     

Truncated diastereoselective Passerini reaction, a rapid construction of polysubstituted oxazole and peptides having an α-hydroxy-β-amino acid component

The reaction of aldehydes and ketones, including aliphatic and aromatic ones, with amides of α-isocyano-β-phenylpropionic acid in toluene in the presence of lithium bromide gives 2,4,5-trisubstituted oxazoles in good to excellent yield. Protected chiral α-amino aldehydes participate in this reaction to give, after hydrolysis of the oxazoles, norstatine-containing peptides in good overall yield. The nucleophilic addition of isonitriles to N,N-dibenzylphenylalanal is investigated for the first time and is found to be stereoselective leading predominantly to the anti-adduct (dr=9/1). On the other hand, the reaction between the N-Boc phenylalanal and isonitrile is non-stereoselective.     

Development of aqueous oxidative Ugi-type reactions by copper-catalyzed surfactant-promoted C(sp)–H direct functionalization in water

Direct assembly of α-amino amides from N-alkyl amines and isocyanides through oxidative Ugi-type reactions in aqueous conditions, has been achieved in a Cu(I)–TBHP–surfactant catalysis system. Various N-alkyl amines and isocyanides could be tolerated in this reaction and furnish α-amino amides in moderate yields.     

Base-promoted aromatic [3,3] sigmatropic rearrangement of N-acyl-O-arylhydroxylamine derivatives

The base-promoted aromatic [3,3] sigmatropic rearrangement of N-acyl-O-arylhydroxylamines giving α-(2-hydroxyphenyl)amides was successfully demonstrated. The substrates were prepared from N-substituted hydroxylamines by N-acylation followed by copper(I)-mediated O-arylation with boronic acids. Treatment of the substrates with lithium hexamethyldisilazide (LiHMDS) in THF at 0?°C to room temperature generated the corresponding amide enolates. The aromatic [3,3] rearrangement of the enolates provided the desired products in moderate to good yields. A crossover experiment produced only intramolecular products and clarified that the reaction proceeds via the aromatic [3,3] sigmatropic rearrangement, not a bond-cleavage–recombination process. Our method is a formal α-arylation of amides.     

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.     

A solventless protocol for the Michael addition of aromatic amides to α,β-unsaturated esters promoted by microwave irradiation

A very simple and efficient solvent-free method for the preparation of N-benzoylated β-amino esters (protected β-amino acids) via the microwave-assisted Michael addition of aromatic amides to α,β-unsaturated esters in the presence of Cs₂CO₃ and tetrabutylammonium bromide (TBAB) is described. The advantages of this method are efficiency, high yields and short reaction times.     

A straightforward synthesis of N-monosubstituted α-keto amides via aerobic benzylic oxidation of amides

An efficient sodium bicarbonate promoted aerobic oxidation reaction to prepare N-monosubstituted α-keto amides in the presence of n-tetrabutylammonium hydrogensulfate (TBAHS) was described. This reaction provides a very simple and convenient synthetic route to N-monosubstituted α-keto amides from easily available aryl- or heteroarylacetamides in good to high yields without using toxic reagents and harsh conditions.     

Ultrasound-Promoted Rapid and Efficient Iodination of Aromatic and Heteroaromatic Compounds in the Presence of Iodine and Hydrogen Peroxide in Water

A rapid and efficient ultrasound-promoted protocol for iodination of aromatic and heteroaromatic compounds, using molecular iodine in the presence of aqueous hydrogen peroxide in water without any cosolvent, has produced versatile iodinated organic molecules with potential application in organic synthesis and medicine in short reaction times and good to excellent yields.     

A new method for the preparation of functionalized unnatural α-H-α-amino acid derivatives

A new method for the preparation of α-H-α-amino acids is reported based on the α-alkylation of iminoacetic acid esters or amides. These imines are readily available by the reaction of glyoxylic acid esters with branched primary amines. The subsequent reaction with methanolic ammonia gave the corresponding iminoacetic acid amides. α-Alkylation of these imines with various electrophiles under basic conditions, followed by an acidic hydrolysis, gave α-amino acids, esters, or amides in up to 93% yield. α-Alkylation under chiral PTC conditions resulted in mono-alkylated amino acids with 90% ee.     

Efficient and eco-friendly synthesis of iodinated aromatic building blocks promoted by iodine and hydrogen peroxide in water: a mechanistic investigation by mass spectrometry

The reaction of aromatic and heteroaromatic compounds with molecular iodine in the presence of aqueous hydrogen peroxide using water without any co-solvent at 50 °C for 24 h produced versatile iodinated organic molecules with potential application in organic synthesis and medicine in very good yields. In addition, a mechanistic investigation for the iodination process was carried out by mass spectrometry.     

Oxidative fragmentation of oxiranes to nitriles with hypervalent iodine(V) reagents in aqueous ammonia

Oxiranes undergo oxidative fragmentation when treated with hypervalent iodine(V) reagents particularly o-iodoxybenzoic acid in aqueous ammonia to give nitriles. The reaction goes via the formation of 1, 2-amino alcohols as intermediates followed by C-C bond cleavage.     

Poly(ethylene terephthalate) waste recycling and uses for enhancement of bioremediation of arsenic in groundwater

Various studies on arsenic pollution reveal that high concentrations of arsenic were found in many districts of western Uttar Pradesh, India. There arsenic concentrations were higher than the permissible limit given by the World Health Organization (WHO) and Bureau of Indian Standards (BIS). There is a requirement to bioremediate arsenic due to its harmful effect. On the other hand, Poly(ethylene terephthalate) was being repeatedly used as packaging materials, due to which various environmental issues regarding PET waste disposal have generated. In the present study, PET waste was recycled into various aromatic amides by aminolysis and ammonolysis. These aromatic amides were used as surfactants. Various studies have been carried out for biosorption of heavy metal through Bacillus cereus. The efforts were made to enhance bioremediation of arsenic in different water samples spiked with Bacillus cereus in the presence of synthesized aromatic amides. This study explored the possibility to increase bioremediation of arsenic by bacteria using recycled PET waste. The results of this study indicated that in the presence of aromatic amides the percent biosorption could be enhanced by bacteria up to 20–60%.The other significant approach of this study is recycling of PET waste.     

Study on the propylphosphonic anhydride (T3P®) mediated Ugi-type three-component reaction. Efficient synthesis of an α-amino amide library

In the present work, a mild and simple synthesis of α-amino amides has been developed via the one-pot three-component ABC type Ugi reaction of a wide variety of aromatic aldehydes and primary aromatic amines, and two different aliphatic isocyanides. The reactions took place rapidly at room temperature in the presence of 1-propanephosphonic acid cyclic anhydride (T3P^®), rendering possible the highly efficient preparation of an α-amino amide library in medium to excellent yields. This study represents the first case in which T3P^® has been used in the Ugi reaction.     

Facile preparation of aromatic esters from aromatic bromides with ethyl formate or DMF and molecular iodine via aryllithium

Various aromatic bromides were treated with n-BuLi and subsequently with ethyl formate, followed by the reaction with ethanol and molecular iodine in the presence of K₂CO₃ to provide the corresponding aromatic ethyl esters in good yields. Moreover, aromatic bromides could be transformed into the corresponding aromatic methyl esters in good yields by the treatment with n-BuLi and subsequently with DMF, followed by the reaction with methanol, molecular iodine, and K₂CO₃. Some aromatics could be also converted into the corresponding aromatic esters in good yields by the treatment with n-BuLi, and subsequently with ethyl formate or DMF, followed by the reaction with molecular iodine and K₂CO₃. The present reactions offer a novel route for the transition-metal-free, carbon-monoxide-free, and therefore environmentally benign one-pot conversion of aromatic bromides and aromatics into aromatic esters.     

Aza-Ferrier rearrangement of glycals with amides promoted by molecular iodine

Amidoglycosidation of tri-O-acetyl-d-glucal with different N-nucleophiles such as t-butyl carbamate, N-benzyl carbamate, N-ethyl carbamate, tosyl amide, and mesyl amide has been achieved using an equimolar amount of molecular iodine under mild and neutral conditions to afford the corresponding N-glycosyl amides in good yields with a preferential α-anomeric selectivity. The use of iodine makes this method simple, convenient, and cost-effective. This is the first report on aza-Ferrier rearrangement using molecular iodine.     

Efficient and Divergent Synthesis of α-Halogenated Amides and Esters by Double Electrophilic Activation of Ynamides

An efficient and modular entry to α-halogenated amides and esters is reported. This reaction is based on an underestimated double electrophilic activation of ynamides sequentially involving highly reactive activated keteniminium and iminium ions. Upon simple reaction with HCl and an electrophilic halogenation reagent in the presence of water or an alcohol, a broad range of ynamides can be transformed, in a highly divergent manner, to α-halo amides and esters with high efficiency and under mild conditions.     

Intermolekulare CC-verknüpfung von azanickelacyclopentanonen, α,ω-disäureamide aus alkenen und phenylisocyanat

The reaction mode of the nickela five-membered ring complexes, prepared from phenyl isocyanate and the alkenes ethene, propene and styrene at (Lig)Ni⁰ systems, with oxidizing reagents such as FeCl₃ and iodine are reported. Depending on the ligands, either unsaturated acid amides are formed or α,ω-diacid amides result by intermolecular CC bond formation. In this way the azanickela seven-membered ring complexes yield linear 1,8-diacid amides.     

Iron-catalyzed hydroaminocarbonylation of alkynes: Selective and efficient synthesis of primary α,β-unsaturated amides

α,β-Unsaturated primary amides are important intermediates and building blocks in organic synthesis. Herein, we report a ligand-free iron-catalyzed hydroaminocarbonylation of alkynes using NH₄HCO₃ as the ammonia source, enabling the highly efficient and regioselective synthesis of linear α,β-unsaturated primary amides. Various aromatic and aliphatic alkynes are transformed into the desired linear α,β-unsaturated primary amides in good to excellent yields. Further studies show that using NH₄HCO₃ as the ammonia source is key to obtain good yields and selectivity. The utility of this route is demonstrated with the synthesis of linear α,β-unsaturated amides including vanilloid receptor-1 antagonist TRPV-1.     

Cesium carbonate promoted aerobic oxidation of arylacetamides: an efficient access to N-substituted α-keto amides

A novel cesium carbonate promoted aerobic oxidation reaction to prepare N-substituted α-keto amides in the presence of catalytic amount of tetra-n-butylammonium bromide was described. This reaction provides a very simple and convenient route from easily available arylacetamides in good to high yields.