Hypervalent Iodine–Catalyzed Cycloaddition of Nitrile Oxides to Alkenes

A new and convenient method for preparation of isoxazolines was developed by a catalytic cycloaddition of nitrile oxides generated in situ from aldoximes to alkenes in the presence of a catalytic amount of iodobenzene. In this protocol, iodobenzene was first oxidized into the hypervalent iodine intermediate by m-chloroperbenzoic acid, which then transformed aldoximes into nitrile oxides, and a 1,3-dipolar cycloaddition of nitrile oxides to alkenes to provide the isoxazolines in moderate to good yields.

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Triflic Anhydride: A Mild Reagent for Highly Efficient Synthesis of 1,2-Benzisoxazoles,Isoxazolo, and Isothiazolo Quinolines Without Additive or Base

The synthetic utility of trifluoromethanesulphonic anhydride (triflic anhydride, TA) without additive or base for the high-yielding synthesis of a wide variety of 1,2-benzisoxazoles from 2-hydroxyaryl aldoximes and ketoximes under mild conditions has been carried out for the first time. As a continuation of our study, syntheses of isoxazolo and isothiazolo quinolones have also been demonstrated using triflic anhydride under similar conditions. This method is simple and has benefits from the easy way to isolate the products in excellent yields.

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Pd-Catalyzed Cross-Coupling of Acyl Chlorides with In Situ–Generated Alkynylzinc Derivatives for the Synthesis of Ynones

A mild and operationally simple procedure by Pd-catalyzed cross-coupling of acyl chlorides with in situ–generated alkynylzinc derivatives was developed, giving the corresponding ynones in good yields.

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In Situ Demethoxylation,Dechloridation, or Decyanogenation from Coupling Aromatic Compounds Mediated by Potassium Metal

The potassium metal can promote direct arylation of unactivated aromatic C-H bonds under an oxygen atmosphere. Interestingly, in situ demethoxylation, dechloridation, or decyanogenation from the corresponding coupling aromatic compounds mediated by potassium metal was also observed in the radical reaction systems.

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Efficient Synthesis of Pyrrolo[1,2-f]phenanthridine Derivatives via Dipolar Cycloaddition of Phenanthridine,Activated Acetylenes,and Ethyl Bromopyruvate

The three-component reactions of phenanthridine, activated acetylenes, and ethyl bromopyruvate through both of simultaneous and stepwise process are surveyed. The reactions afforded the corresponding pyrrolo[1,2-f]phenanthridine derivatives in good yields without using any catalyst and activation.

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One-Pot,Catalyst-Free Synthesis of Spirooxindole and 4H-Pyran Derivatives

The synthesis of biologically valuable spirooxindoles and 4H-pyrans is described under catalyst-free conditions through sequential Knoevenagel–Michael–cyclization reactions from isatin or aromatic aldehyde, malononitrile, and 1,3-dicarbonyl compounds. The reaction conditions are very simple, providing excellent yield.

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Asymmetric Synthesis of Novel Vicinal Amino Alcohols via Intramolecular Ketone-N-sulfinylimine Pinacol-Type Reductive Coupling Promoted by SmI2

A novel intramolecular asymmetric ketone-N-sulfinylimine pinacol-type reductive coupling reaction induced by SmI₂ was reported. A series of 1-amino-1,2,3,4-tetrahydronaphthalen-2-carbinols were obtained in moderate to good yields with excellent ee and high dr.

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Role of Additives in Chiral Amine-Catalyzed Direct Aldol Reaction

A systematic study of chiral adducts derived from amines as catalysts for aldol reaction revealed that enantioselective outcome depends on the chiral enamine intermediate and not the face-selective activation of aldehyde. A simple addition compound of proline and 8-hydroxy quinoline was found to be a good catalyst.

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Highly Stereoselective Cyclopropanation of Olefins Catalyzed by a Novel C 3-Symmetric Arsine

A novel C ₃-symmetric arsine was employed in the one-pot cyclopropanation of olefins with carbonyl-stabilized arsonium ylides formed in situ from phenacyl bromide in the presence of NaHCO₃. This new arsine demonstrates good stereoselectivity and activity in the one-pot cyclopropanation of arylidenemalononitrile.

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K3PO4-KOH Mixture as Efficient Reagent for the Deprotection of 4-Aryl-2-methyl-3-butyn-2-ols to Terminal Acetylenes

A mixture of potassium hydroxide and potassium phosphate was found to be an active reagent mixture for the cleavage of 2-hydroxypropyl-protected acetylenes. The reaction was performed in toluene at reflux temperature and gave terminal acetylenes in good to excellent yields within very short periods of time. Numerous other functional groups are tolerated.

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Solvent-Free Synthesis of Dihydropyridines and Acridinediones via a Salicylic Acid–Catalyzed Hantzsch Multicomponent Reaction

A multicomponent Hantzsch synthesis of 1,4-dihydropyridines and acridinediones from commercially available aldehydes, ammonium acetate, and ethyl acetoacetate or dimedone, in the presence of salicylic acid as an efficient catalyst, in good yield and short reaction time is reported.

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Synthesis of Biaryls via Pd-Catalyzed Decarboxylative Coupling of Substituted Benzoic Acids with Phenylboronic Acids

A Pd-catalyzed decarboxylative coupling of substituted benzoic acids with phenylboronic acid has been developed. Under the optimized conditions, a variety of substituted benzoic acids were found to undergo decarboxylative coupling with various phenylboronic acids to give the desired unsymmetrical biaryls in good yields.

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Metal-Free,One-Pot Oxidative Conversion of Aldehydes to Primary Thioamides in Aqueous Media

One-pot tandem reactions of a variety of aldehydes with aqueous ammonia, molecular iodine, and O,O-diethyl dithiophosphoric acid readily afford the corresponding primary thioamides. This is an inexpensive, practical, and metal-free way of accessing various thioamides from aldehydes in aqueous media. The pure products are obtained simply by filtration followed by successive washing with aqueous sodium thiosulfate and water.

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Surfactant-Catalyzed Addition of Higher Thiols to N-Aryl Substituted Maleimides

The cationic-type surfactant-catalyzed conjugate addition reaction of long-alkyl-chained thiols with N-aryl-substituted maleimides in water as a green reaction medium afforded the corresponding thia-Michael adducts in moderate to good yields.

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Selection of Amino Acids and the Biomimetic Synthesis of Amido Bond in the Presence of β-CD

A new method was developed to construct a special amido bond in the presence of β-cyclodextrin. This process is similar to peptide synthesis in organisms. NMR experiments were performed to investigate the possible mechanism. This work has potential application in biomimetic peptide synthesis.

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Mild and Efficient One-Pot Synthesis of 3,5-Disubstituted 1,2,4-Oxadiazoles from Nitriles Mediated by K3PO4

Potassium phosphate, K₃PO₄, has been proved to be a cheap, strong, and efficient reagent for the one-pot synthesis of 3,5-disubstituted-1,2,4-oxadiazoles from nitriles and acid chlorides under mild conditions.

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Ferrocenoyl Benzotriazole,IV: Microwave-Assisted Synthesis of Novel 1,1′-Bis-ferrocenamides

An easily applicable microwave-assisted novel 1,1′-bis-ferrocenoylbenzotriazole-mediated synthesis of novel derivatives for 1,1′-bis-ferrocenamides was applied. This is a cheap, easy, and green method because of microwave irradiation and recovery of benzotriazole.

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Synthesis,Characterization, and Antibacterial Activity of Novel Pyridones

Novel ethyl 2-oxo-4,6-diaryl-1,2,3,4-tetrahydropyridine-3-carboxylate and 4,6-diaryl-3,4-dihydropyridine-2(1H)-one derivatives have been synthesized from the cyclization of adducts of diethylmalonate to chalcones with ammonium acetate. The structures were established on the basis of extensive spectroscopic methods and further confirmed by X-ray crystallographic analysis. Antibacterial activity of obtained pyridones was investigated against four human pathogen microorganisms and the compounds showed poor activity.

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Recyclable,Graphite-Catalyzed,Four-Component Synthesis of Functionalized Pyrroles

A facile, convenient, and multicomponent coupling strategy for the synthesis of highly functionalized pyrroles is developed using graphite as a catalyst, but devoid of moisture-sensitive metal catalysts and corrosive acidic reagents. This method involves four-component coupling reactions of ethyl acetoacetate compound or diethyl acetylene dicarboxylate, amines, aromatic aldehydes, and nitromethane without an inert atmosphere. This approach provides easy access to highly substituted pyrroles in good yields via one-pot tandem reaction. The method is very simple, straightforward, and environmentally friendly compared to the existing methods.

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Aldonitrones as Aldehyde Equivalents: An Efficient,Green, and Novel Protocol for the Synthesis of 1,8-Dioxo-octahydroxanthenes

A novel, self-catalyzed, solvent-free, microwave-enhanced, green, and efficient protocol for the synthesis of 1,8-dioxo-octahydroxanthenes and bis-5,5-dimethyl-1,3-cyclohexanediones by condensing aldo-nitrones (imine oxide) and dimedone (5,5-dimethyl-1,3-cyclohexanedione) under microwave irradiation is disclosed. Product formation (viz. xanthenes and bis-5,5-dimethyl-1,3-cyclohexanediones) is dependent on reaction conditions. The entire process is green and sustainable in terms of solvents, chemicals, reaction procedure, and yields. A plausible reaction mechanism of this reaction is also proposed.

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