Indium-mediated mild and facile method for the synthesis of amides

Indium-mediated coupling reactions of acyl chlorides and amines for the synthesis of amide bonds are described. The reaction afforded high yields of the desired amides under mild and neutral conditions, and it was applicable also to the preparation of peptides without epimerization.     

Preparation of selenofunctionalized heterocycles via iodosobenzene-mediated intramolecular selenocyclizations of olefins with diselenides

An intramolecular selenocyclizations of olefins mediated by a commercially available hypervalent iodine(III) reagent, PhIO, was developed. This method provided access to a wide range of selenenylated heterocycles under ambient conditions. The striking advantages of this protocol over all previous methods include mild reaction conditions, easy operation, good yields, high levels of functional group compatibility, large–scale application and suitability for the late-stage functionalization of complex molecules of biological importance.     

Heteropoly acids: a green and efficient heterogeneous Brønsted acidic catalyst for the intermolecular hydroamination of olefins

Intermolecular hydroamination of non-activated olefins with amides and benzyl carbamate proceeds efficiently in the presence of environmentally benign silicotungstic acid (HSiW) catalyst under mild conditions in air to afford addition products in good to excellent yields.     

A facile one-step preparation of chlorofluoromethylene olefins

The “insitu” reaction of triphenylphosphine, fluorotrichloromethane, zinc dust, and an aldehyde or ketone in dimethylformamide at 60°C provides a facile one-step synthesis of chlorofluoromethylene olefins. A study of representative examples of carbonyl compounds demonstrates that this approach gives yields of olefinic products comparable to other more elaborate or expensive synthetic routes. It should prove to be synthetically useful for the preparation of chlorofluoromethylene olefins from aldehydes and reactive ketones.     

New investigation of Vilsmeier-type reaction using pyrazolones with various amides

New investigation of Vilsmeier-type reaction was evaluated to realize the solvent effect by using pyrazolones to react with various of amides, including formamide, N-methylformamide, N-propylformamide, N-tert-butylformamide, N,N-dimethylformamide (DMF), N,N-diethylformamide (DEF), N,N-dipropylformamide (DPF), N,N-diisopropylformamide, N,N-dibutylformamide, piperidine-1-carbaldehyde, and pyrrolidine-1-carbaldehyde, in the presence of phosphorous oxychloride POCl₃. The unexpected resulting products were observed in this work according to the difference chemoseletivities of substituted amides. The plausible reactive pathways were proposed to explain the experimental result.     

p-Tolylsulfinyl amides: reagents for facile electrophilic functionalization of olefins

A variety of olefins were found to react with sulfinyl amides in the presence of POCl(3) to give beta-chlorosulfides and beta-hydroxysulfides in good yields. In the absence of nucleophiles, p-tolylsulfinyl amides were found to react with olefins with the formation of allylsulfoxides.     

Acylation of sugar amides over Algerian bentonite and mcm-41 materials

The condensation of sugar with fatty acids in an organic media is possible by chemical amidification without fastidious steps by hydroxyl group protection/deprotection. The acylation of sugar (N-methyl glucamine) with fatty acids (lauric acid, palmitic acid and stearic acid) is catalyzed in the presence of two inorganic and acid solid catalysts: Algerian clay called bentonite of Maghnia and mesoporous material of type (Al–MCM-41). The results obtained with this last solid (i.e. MCM-41) are very encouraging.     

Synthesis of 2-oxazolines and related N-containing heterocycles using [Et2NSF2]BF4 as a cyclodehydration agent

The preparation of 2-oxazolines and related N-containing heterocycles from the corresponding hydroxyamides using XtalFluor-E ([Et₂NSF₂]BF₄) as a cyclodehydration agent is described. A wide range of heterocycles are obtained under mild conditions in good to excellent yields.     

An atom efficient and solvent-free synthesis of structurally diverse amides using microwaves

An array of structurally diverse amides was synthesized efficiently by combining (primary and secondary) amines and carboxylic acids in one-pot under solvent-free microwave (MW) conditions. In most cases, no racemization was observed with optically active inputs and chiral amides were obtained in high ee or de.     

Scandium triflate catalyzed ester synthesis using primary amides

A scandium triflate (ScOTf)₃ catalyzed methodology has been developed to synthesize esters from primary amides. Various primary and secondary aliphatic alcohols have been shown to react in n-heptane with a range of primary amides for 24 h.     

A facile preparation of selenohydantoins using isoselenocyanate

Reactions of isoselenocyanate with methyl aminoacetate hydrochlorides in the presence of triethylamine afforded selenohydantoins, 2‐selenoxoimidazolidin‐4‐ones, in high yields.     

Direct synthesis of oxazolines from olefins and amides using t-BuOI

A new and simple method for the synthesis of oxazolines from readily accessible olefins and amides using tert-butyl hypoiodite is described; aromatic/aliphatic olefins and amides can be used in the reaction to give a variety of oxazolines.     

Divergent Photosensitizer Controlled Reactions of 4-Hydroxycoumarins and Unactivated Olefins: Hydroarylation and Subsequent [2+2] Cycloaddition

Herein, we report a photoinduced approach for hydroarylation of unactivated olefins using 4-hydroxycoumarins as the arylating reagent. Key to the success of this reaction is the conversion of nucleophilic 4-hydroxycoumarins into electrophilic carbon radicals via photocatalytic arene oxidation, which not only circumvents the polarity-mismatch issue encountered under ionic conditions but also accommodates a broad substrate scope and inhibits side reactions that were previously observed. Moreover, divergent reactivity was achieved by changing the photocatalyst, enabling a subsequent [2+2] cycloaddition to deliver cyclobutane-fused pentacyclic products that are otherwise challenging to access in high yields and with high diastereoselectivity. Mechanistic studies have elucidated the mechanism of the reactions and the origin of the divergent reactivity.     

A facile method for oxytelluration of olefins

Treatment of olefins with phenyltellurium(I) or (IV) species [(PhTe)₂, PhTeCN, PhTeBr₃] in alcohol at room to reflux temperature for 1–24 h produces the corresponding (2-alkoxyalkyl)phenyltellurium dihalides in good yields, the reaction being trans-stereoselective and highly regioselective.     

A facile direct conversion of aldehydes to esters and amides using acetone cyanohydrin

Aromatic aldehydes with electron-withdrawing groups undergo rapid reactions with a variety of alcohols and secondary amines to afford the corresponding esters and amides, respectively, in high yields, when treated with NaCN or acetone cyanohydrin and base under ambient reaction conditions. In case of α,β-unsaturated aldehydes, simultaneous reduction of the CC bond along with esterification occurred to produce the saturated esters in high yields.     

A facile access to bridged 1,2,4-trioxanes

Bicyclo[3.2.1] type 1,2,4-trioxanes are readily synthesized from precursors that may form intramolecular hemiketals using UHP (H₂O₂-urea complex) as the source of the peroxy bond and p-TsOH or CSA as the catalyst. The ring closure through an intramolecular Michael addition occurred in a highly stereoselective way, giving only one diasteromer as shown by the NMR spectra.     

Photochemical C–N bond forming reactions for the synthesis of five-membered fused N-heterocycles

Abstract

Few conversions cannot take place with ground-state reactions even with the help of a catalyst, therefore they are made to occur under photochemical conditions. The transfer of electrons took place even with the photochemical excitement of one molecule where redox reaction cannot occur at the ground state. The ground-state reactions resulted in the formation of side products. The substrates did not require any sort of chemical activation for C–N bond construction in the course of photochemical reactions. The source of energy; light has always been the interest of researchers in order to induce chemical reactions ever since the starting of scientific chemistry. The present review encloses the chemistry of photochemical transformations with a focus on their synthetic uses. The organic photochemical reactions prevent the polluting or harmful reagents thus, provides a possibility for sustainable procedures as well as green chemistry. This review article displays the formation of numerous of five-membered fused nitrogen-heterocyclic compounds.     

Alder-ene reaction of aryne with olefins

A novel intermolecular Alder-ene reaction based on aryne and olefins was developed. We performed this transformation under mild conditions such as at room temperature, and this reaction displayed high selectivity and good yields only in the presence of CsF. Hence, the intermolecular Alder-ene reaction of aryne with olefins provides an effective route to synthesize derivatives of olefins.     

A novel and efficient catalytic epoxidation of olefins and monoterpenes with microencapsulated Lewis base adducts of methyltrioxorhenium

The reactivity of methyltrioxorhenium in the epoxidation of olefins can be tuned by the presence of Lewis bases as ligands of the metal center. Unfortunately, a large excess of ligand is usually required to obtain high yields and selectivities mainly because of the fluxional behaviour that these compounds show in solution. We describe here the microencapsulation technique that can resolve this problem. Microencapsulated Lewis base adducts of methyltrioxorhenium with nitrogen containing ligands are highly efficient and selective catalysts for the epoxidation of several olefins and monoterpenes with hydrogen peroxide even in the case of the most sensitive substrates. These systems show the advantages of the ligand accelerated catalysis and the benefits of heterogeneous compounds. They can be easily recovered from the reaction mixture and used for more transformations.     

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.