Palladium-Catalyzed Oxidative Carboacetoxylation of Activated Alkynes with Amino Acids

A palladium-catalyzed intramolecular oxidative carboacetoxylation reaction of alkynes with various amino acids has been demonstrated for the first time, forming pharmaceutically important 3-methyleneindolin-2-one. In the presence of Pd(OAc)₂ and ArI(OAc)₂, N-arylpropiolamides underwent tandem acetoxypalladation/C-H functionalization reactions with various Boc-amino acids to form corresponding methyleneindolin-2-ones bearing amino acid motifs in moderate to excellent yields.

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Synthesis of a Series of Hydroxycarboxylic Acids as Standards for Oxidation of Nonanoic Acid

The synthesis of a series of nonanoic acids hydroxylated in terminal,ω-1,ω-2,ω-3 positions is described. These compounds will be employed as useful standards for the study of enzymatic and microbiological oxidation of nonanoic acid.

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Bromination of Arenes Using I2O5-KBr in Water

An efficient and environmentally benign bromination of various aromatic compounds using aN aqueous I₂O₅-KBr system at room temperature has been developed in this work. A series of aromatic compounds such as acetophenones, benzaldehydes, benzoic acids, anilines, amides, and aminopyridine have been successfully brominated in excellent regioselectivities and good yields under the typical reaction conditions. The features of KBr as brominating reagent, water as solvent, and mild conditions make this system an attractive synthetic procedure.

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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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Oxidation of Benzaldehydes to Benzoate Esters Using Household Bleach and Sodium Iodide in Alcohol Solvents

Various substituted benzaldehydes were converted into benzoate esters with household bleach and sodium iodide in an alcohol solvent. The reaction works best with methanol. Only 4-chlorobenzaldehyde, 3-nitrobenzaldehyde, and 4-nitrobenzaldehyde reacted completely with 1-propanol under these conditions.

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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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Synthesis and CuAAC Reactions of Azidoalkylethoxysilanes: Grafting CuAAC Products onto Silica Surface

One-pot synthetic protocols of novel azido functionalized silane coupling agents from corresponding terminal mesylated or tosylated 1-olefins were developed. Azido groups were successfully converted to the corresponding 1,2,3-triazol ring by the copper-catalyzed azido alkyne coupling (CuAAC) reaction without alkoxysilane decomposition. The CuAAC product was readily grafted onto the silica surface in good yield.

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Synthesis of Novel Asymmetrical Single-Chain Phosphoglycol-Based Bolaamphiphiles

The synthesis of long-chain 1,ω-diols with orthogonal cleavable protecting groups can be effectively performed with the use of the Grignard coupling reaction, successfully leading to the preparation of novel asymmetrical single-chain phosphoglycol-based bolaamphiphiles—a side-product that always occurred during the synthesis of symmetrical bolalipids.

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C-S Bond-Forming Reactions of Barbiturylbromide with Isothiocarbamides in Aqueous Media

The C-S cross coupling of pharmaceutically active barbituric acid derivatives has been achieved by the interaction of selective monobromobarbituric acid with thioureas in an aqueous medium. This method is applicable for simple thiourea as well as monosubstituted thioureas, and corresponding products are obtained in good yield.

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Convenient Synthesis of Monobenzylated Hydrazides via Aqueous Zinc-Mediated Addition Reactions

Addition of substituted benzyl bromides to dialkyl azodicarboxylates under aqueous zinc-mediated addition conditions occurs readily to afford monobenzylated hydrazides in good to excellent yields. The reaction is tolerant of a variety of substituents on the benzyl bromide ring. Several dialkyl azodicarboxylates were successfully tested under the reaction conditions. The limitations of the reaction are also addressed.

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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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Three-Component Synthesis and 1,3-Dipolar Cycloaddition of Highly Functionalized Pyrans with Nitrile Oxides: Easy Access to 1,2,4-Oxadiazoles

Three-component reaction of 1-[(4-chlorophenyl)sulfanyl]acetone, malononitrile, and substituted aromatic aldehydes in the presence of sodium ethoxide under simple mixing at ambient temperature for 5–8 min afforded highly functionalized 4H-pyrans in good to excellent yields. 1,3-Dipolar cycloaddition of nitrile oxides over the nitrile functionality of the 4H-pyrans furnished 1,2,4-oxadiazoles in moderate yields.

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Free Radical–Mediated Chemoselective Reduction of Enones

A novel methodology has been devised for the chemoselective reduction of enones involving the use of ⁿ Bu₃SnH and azobisisobutyronitrile. The 1,4-reduction of variously substituted α,β-unsaturated cyclic and acyclic enones has been successfully carried out under free radical reaction conditions. The reaction has been determined to proceed via single-electron transfer.

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Copper bis(2,2,6,6-Tetramethyl-3,5-heptanedionate)–Catalyzed Coupling of Sodium Azide with Aryl Iodides/Boronic Acids to Aryl Azides or Aryl Amines

This work reports an efficient protocol for the coupling reaction of aryl iodides/boronic acids with sodium azide to aryl azides/amines in the presence of copper bis(2,2,6,6-tetramethyl-3,5-heptanedionate) Cu(TMHD)₂ catalyst. The Cu(TMHD)₂ catalyst is a structurally well-defined, O-containing, air- and moisture-stable, transition-metal complex and works at mild reaction conditions. It was observed that aryl azides can be reduced further to corresponding aniline derivatives using the same catalyst under basic reaction conditions for a prolonged period.

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Synthesis of N,N-Diethylbenzamides via a Nonclassical Mitsunobu Reaction

The use of the Mitsunobu reaction for the synthesis of N,N-diethylbenzamides affords ortho-, meta-, and para-substituted benzamides containing both electron-donating and electron-withdrawing groups. While the preparation of numerous functional groups has been efficiently demonstrated employing the Mitsunobu reaction, our methodology represents the first application of the Mitsunobu reaction for the construction of benzamides using benzoic acid and amine starting materials. Moreover, this synthetic transformation is believed to proceed via a nonclassical mechanism involving the existence of an acyloxyphosphonium ion.

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One-Pot Microwave-Assisted Synthesis of 3,4-Disubstituted 2-Quinolinones

An improved one-pot synthesis of 3,4-disubstituted 2-quinolinones is described. The condensation of substituted 2-aminobenzophenone (or 2-aminophenyl alkyl ketone) with acid chlorides was carried out in the presence of triethylamine (or NaH) under microwave reaction conditions (150oC, 200 psi). The reactions were completed within minutes to produce 2-quinolinones in moderate to excellent yields and good purities.

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Diprotodecarboxylation Reactions of 3,4-Dialkoxythiophene-2,5-dicarboxylic Acids Mediated by Ag2CO3 and Microwaves

An efficient and rapid method is reported to obtain 3,4-dialkoxythiophenes from 3,4-dialkoxythiophene-2,5-dicarboxylic acids through a diprotodecarboxylation reaction with Ag₂CO₃/AcOH as a catalytic system and microwave heating in dimethylsulfoxide (DMSO) as solvent. This methodology lets us obtain for the first time good performance with thiophenes bearing strong electron-donating groups such as alkoxides. This methodology eliminates the usage of harmful quinoline as solvent, as well as the long reaction times typically used (12–18 h) to obtain the 3,4-dialkoxythiophenes. The reaction of 7 diacids showed good yields (60–89%) following 20 min of microwave heating in a temperature range of 120–150 °C.

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Metal-Free,One-Pot,Rapid Synthesis of Tetrahydropyridines Using Acetic Acid as Solvent and Catalyst at Room Temperature

Acetic acid–promoted, one-pot synthesis of tetrahydropyridines has been developed under metal-catalyst-free conditions via a tandem reaction. High atom economy, good yield, simple procedure, no expensive column chromatography, shorter reaction time, and metal-free and mild reaction conditions are some of the important features of this protocol. The current methodology provides an alternative approach for not only highly substituted tetrahydropyridines (THPs) but also fully substituted tetrahydropyridines (FTHPs) in moderate to good yields. The plausible mechanism for the formation of THPs was greatly promoted by the H⁺ ion coming from acetic acid.

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Unexpected Transformation of Aldehydes into Benzoins with Copper(I)/Samarium

The reductive coupling of aldehydes to afford pinacolic alcohols using all kinds of reducing agents involving samarium is well known. In this report, however, treatment of aromatic aldehydes with Cu(I)/Sm system produces benoins and/or benzils in good yields. A possible mechanism is proposed where Cu(I) not only activates the Sm metal but also promotes the dehydrogenation of the intermediates, during which a Cu(III) species may be involved.

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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.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]