Showing papers in "Synthesis in 2010"
TL;DR: In this paper, a review focusing on recent achievements in the development of enantioselective transforma- tions using these axially chiral phosphoric acids and their analogues as chiral Bronsted acid catalysts is presented.
Abstract: Chiral phosphoric acids derived from axially chiral biar- yls and related chiral Bronsted acids have emerged as an attractive and widely applicable class of enantioselective organocatalysts for a variety of organic transformations. This review focuses on recent achievements in the development of enantioselective transforma- tions using these axially chiral phosphoric acids and their analogues as chiral Bronsted acid catalysts. The contents are arranged accord- ing to the specific types of carbon-carbon bond-forming reactions, followed by carbon-heteroatom bond-forming reactions and func- tional group transformations, including reduction and oxidation. Further applications to combined phosphoric acid and metal com- plex catalytic systems and new aspects in the development of chiral Bronsted acid catalysts are also highlighted.
1,016 citations
TL;DR: A review of the applications of cinchona alkaloids as asymmetric catalysts can be found in this article, with an overview of the transformations developed in the period from 2001 through 2009, highlighting applications in the synthesis of bioactive molecules and natural products.
Abstract: This article reviews the applications of cinchona alkaloids as asymmetric catalysts. In the last few years, characterized by the resurgence of interest in asymmetric organocatalysis, cinchona derivatives have been shown to catalyze an outstanding array of chemical reactions, often with remarkable stereoselectivity. This work presents an overview of the transformations developed in the period from 2001 through 2009, highlighting applications in the synthesis of bioactive molecules and natural products.
367 citations
TL;DR: In this article, the authors summarized progress in this area and summarized the progress in the ORTHO-CINE-Arylation and IPSO-Vinylation processes.
Abstract: Arene and heteroarene carboxylic acids undergo regioselectivearylation and vinylation reactions at the positions ORTHO ( CINE)and IPSO to their carboxyl function undertransition-metal catalysis; these reactions are accompanied by carbon-hydrogenand carbon-carbon bond cleavages, respectively Recentprogress in this area is summarized in this article 1 Introduction 2 ORTHO- ( CINE-)Arylation 3 ORTHO- ( CINE-)Vinylation 4 IPSO-Arylation 5 IPSO-Vinylation 6 Conclusions
333 citations
TL;DR: This review is divided into two main sections, the first consisting of oxidative Heck reactions oforganometallic compounds such as organoboranes, organosilanols andarylstannanes, and the second covering oxidative Heck reactionvia C-H activation, a topic which has become an attractive theme in organic synthesis.
Abstract: Oxidative Heck reactions provide a facile and efficient routeto carbon-carbon bond formations. This review is dividedinto two main sections, the first consisting of oxidative Heck reactions oforganometallic compounds such as organoboranes, organosilanols andarylstannanes, and the second covering oxidative Heck reactionsvia C-H activation, a topic which has become an attractive themein organic synthesis. 1 Introduction 2 Oxidative Heck Reactions of Organometallic Compounds 2.1 With Palladium(II) Catalysts 2.1.1 Ligand-Free Reactions 2.1.1.1 Anaerobic 2.1.1.2 Aerobic 2.1.2 Ligand-Based Reactions 2.1.2.1 Aerobic 2.1.2.2 Anaerobic 2.1.3 Asymmetric Reactions 2.1.3.1 Aerobic 2.1.3.2 Anaerobic 2.1.4 With Polymer-Supported Palladium(II) Catalysts 2.2 With Other Transition-Metal Catalysts 2.3 With Other Organometallic Compounds 3 Oxidative Heck Reactions of C-H Compounds 3.1 Catalytic Reactions 3.1.1 Intermolecular Reactions 3.1.1.1 Anaerobic 3.1.1.2 Aerobic 3.1.2 Intramolecular Reactions 3.1.2.1 Anaerobic 3.1.2.2 Aerobic 4 Conclusions and Outlook
182 citations
TL;DR: This review provides an overview of the history of the asymmetric organocatalyzed Diels-Alder reaction and describes a variety of small organic moleculessuch as prolines, imidazolidinones, chiral Bronsted- acids,guanidines, carbenes and CINCHONA alkaloidscan be used as different catalyst systems to induce enantioselectivity.
Abstract: Enantioselective organocatalytic asymmetric Diels-Alder- reactionsprovide a facile and efficient route to optically active functionalizedcyclohexenes, which can be further transformed into a variety ofimportant organic compounds. A variety of small organic moleculessuch as prolines, imidazolidinones, chiral Bronsted- acids,guanidines, carbenes and CINCHONA alkaloidscan be used as different catalyst systems to induce enantioselectivityin the reaction. This review provides an overview of the historyof the asymmetric organocatalyzed Diels-Alder reaction. 1 Introduction 2 Chiral-Base-Catalyzed Diels-Alder Reactions 2.1 Chiral Secondary Amines 2.2 Chiral Primary Amines 2.3 Cinchona Alkaloids 2.4 Heterocyclic Carbenes 2.6 Chiral Guanidines 3 Hydrogen-Bond-Catalyzed Diels-Alder Reactions 4 Concluding Remarks
129 citations
TL;DR: This account systematically summarizes the multicomponent reaction syntheses of novel DHPMs that are notaccessible through the classical Biginelli reaction.
Abstract: The three-component Biginelli reaction for the synthesis of dihydropyrimidinoneand corresponding dihydropyrimidine-thiones (DHPMs) hasbeen known for more than a century. Consistent attention has beenpaid to the study of Biginelli reaction owing to the significantbiological and pharmaceutical merits of DHPMs. In the view of moleculardiversity, the development of new multicomponent reactions thatprovide DHPMs bearing novel functional structures has emerged asa central issue in recent years. This account systematically summarizesthe multicomponent reaction syntheses of novel DHPMs that are notaccessible through the classical Biginelli reaction. 1 Introduction 2 Synthesis of DHPMs via Modification of Classical Biginelli Substrates 2.1 Using β-Keto Ester Alternatives 2.2 Using Urea/Thiourea Alternatives 2.3 Using Aldehyde Alternatives 3 Synthesis of DHPMs via Other Multicomponent Reactions 4 Conclusions
113 citations
TL;DR: In this paper, an overview of the practical methods for preparing symmetrically α,α-disubstituted α-amino cacids and their derivatives is presented.
Abstract: This report provides an overview of the practical methods for
preparing symmetrically α,α-disubstituted α-amino
acids and their derivatives. Despite the growing application of
this particular type of sterically constrained α-amino
acid in the de novo design of peptides
and peptidomimetics, synthetically important achievements in the
field have not been summarized so far. Classical methods, such as
the Bucherer-Bergs and Strecker reactions of sym-dialkyl and cyclic ketones, as well
as recent methods involving dialkylation of nucleophilic glycine
equivalents and Ugi reactions, are presented. 1 Introduction 2 Bucherer-Bergs and Strecker Reactions of sym-Dialkyl and Cyclic Ketones 3 Dialkylation of Schiff Bases Derived from Glycine Esters 4 Dialkylation of Ethyl Isocyanoacetate 5 Dialkylation of Ethyl Nitroacetate 6 Ugi Reaction 7 Conclusions
112 citations
TL;DR: This review describes the efforts as well as those of others in the synthesis of various fluorinated aryl and heteroaryl sulfones and their utility as olefination reagents for the modular assembly of fluoroalkenes.
Abstract: The Julia-Kocienski olefination provides a versatile platform for the synthesis of fluorovinyl compounds. This review describes our efforts as well as those of others in the synthesis of various fluorinated aryl and heteroaryl sulfones and their utility as olefination reagents for the modular assembly of fluoroalkenes. Where data is available, the influence of the fluorine atom on the reactivity of the olefination reagents and the stereochemical outcome of the olefination are described.
85 citations
TL;DR: In this article, the chemoselectivity of ruthenium-catalyzed C-H bond arylations on triazol-4-yl-substituted arenes was found to depend on the substitution pattern of both substrates.
Abstract: The chemoselectivity of ruthenium-catalyzed C-H bond arylations on triazol-4-yl-substituted arenes was found to depend on the substitution pattern of both substrates. While various aryl chlorides led to products stemming from direct arylations, ortho-substituted aryl halides in combination with ortho-alkylated arenes preferentially resulted in oxidative homo-couplings.
84 citations
TL;DR: Isocyanide-based multicomponent reactions (IMCRs) allow for the truly convergent and efficient access to not less than 35 different piperazine derived scaffolds, and their scopes and limitations are discussed.
Abstract: Piperazine scaffolds are amongst the most extensively used backbones in medicinal chemistry and many bioactive compounds are built upon this template. The physicochemical properties and the three-dimensional structures of the different piperazine chemotypes are of utmost importance to understanding its biological activities. Knowing the synthetic access to this chemical space of piperazines is of great importance to designing compounds with better properties. Isocyanide-based multicomponent reactions (IMCRs)allow for the truly convergent and efficient access to not less than 35 different piperazine derived scaffolds. These are reviewed, and their scopes and limitations are discussed. 1 Piperazine Scaffolds in Chemistry and Medicine 2 Chemical Space of Piperazines via Isocyanide-Based Multicomponent Reactions 3 Monocyclic Piperazines 3.1 Piperazine 3.2 Ketopiperazine 3.3 2,5-Diketopiperazine 3.4 2,6-Diketopiperazine 4 Bicyclic Fused Piperazines 5 Polycyclic Fused Piperazines 6 Introduction of the Piperazine Moiety via a Starting Material 7 Conclusions and Outlook. © 2010 Georg Thieme Verlag Stuttgart New York.
79 citations
TL;DR: In this article, a comprehensive account of transition-metal-catalyzed cross-coupling reactions to form C-P bonds is presented, which is organized according to the hybridization of the carbon coupling partner, the numerousphosphorus coupling partners are discussed individually.
Abstract: This review is a comprehensive account of transition-metal-catalyzedcross-coupling reactions to form C-P bonds. Organized accordingto the hybridization of the carbon coupling partner, the numerousphosphorus coupling partners are discussed individually. The severalputative mechanisms of these transition-metal catalyses are alsoincluded, thereby providing insights into both the synthetic andthe mechanistic aspects of this chemistry. A separate section isdevoted to asymmetric C-P cross-couplings. 1 Introduction 1.1 Carbon Coupling Partners 1.2 Phosphorus Coupling Partners 2 C(sp 2 )-P Cross-Coupling 2.1 Elemental Phosphorus as Coupling Partner 2.2 Quaternization and Aryl Exchange at P(III): R 3 Pas Coupling Partners 2.2.1 Quaternization 2.2.2 Aryl Exchange 2.3 Silyl- and Stannylphosphines as Coupling Partners 2.4 Secondary and Primary Phosphines and Derivatives Thereofas Coupling Partners 2.5 Phosphine Chlorides as Coupling Partners 2.6 Phosphites, Phosphonites, Phosphinites and Derivatives Thereofas Coupling Partners 2.7 Hypophosphorous Acid and Derivatives Thereof as CouplingPartners 2.7.1 Hypophosphorous Acid as Coupling Partner 2.7.2 Hypophosphorous Acid Esters (Alkyl Phosphinates) as CouplingPartners 2.8 Secondary Phosphine Oxides as Coupling Partners 2.9 Alkyl Alkylphosphinates and Derivatives Thereof as CouplingPartners 2.10 Dialkyl Phosphites and Derivatives Thereof as Coupling Partners 3 C(sp)-P Cross-Coupling 4 C(sp 3 )-P Cross-Coupling 5 Asymmetric Cross-Coupling Reactions
TL;DR: Blatter's radical (IIa) and related derivatives are prepared from the corresponding amidrazones as discussed by the authors, which are then used to produce the IIa-IIa radical.
Abstract: Blatter′s radical (IIa) and related derivatives are prepared from the corresponding amidrazones.
TL;DR: A review of metal-catalyzed allylation reactions between allylic alcohol derivatives and alkenyl or aryl organoboron compounds can be found in this article.
Abstract: Metal-catalyzed transformations have emerged as indispensabletools for carbon-carbon bond formation in contemporary syntheticchemistry. Metal-promoted cross-couplings and metal-catalyzed allylationsrepresent two of the most widely used reaction types. However, cross-couplingreactions involving allylic electrophiles have not been extensivelyexplored. This review presents an overview of efforts aimed at developingmetal-catalyzed allylation reactions between allylic alcohol derivativesand alkenyl or aryl organoboron compounds, leading to 1,4-dienesand allylic arenes, respectively. Particular emphasis is given toregio- and stereoselective allylation procedures. 1 Introduction 2 Allylations Proceeding through π-Allyl Intermediates 2.1 Palladium Catalyzed 2.2 Nickel Catalyzed 2.3 Rhodium Catalyzed 3 Formal S N 2′-Type Allylations 3.1 Palladium Catalyzed 3.2 Rhodium Catalyzed 4 Conclusions and Future Directions
TL;DR: In this article, a review of the recent advances in the synthetic application of α-amido sulfones as reactive precursors of imines in the context of asymmetric nucleophilic addition of organometallic reagents is presented.
Abstract: Catalytic nucleophilic addition to the carbon-nitrogen doublebond of an imino group in an asymmetric fashion provides a directconnective and attractive route to enantioenriched N-protected amineswith structural diversity. In the last decades, significant achievementshave been made in the field of catalytic enantioselective reactionsinvolving the use of α-amido sulfones as in situ equivalentsof activated imines. These, in combination with diverse nucleophiles,are used to prepare optically pure amines or N-protected amides.This review focuses on the recent advances in the synthetic applicationsof α-amido sulfones as reactive precursors of imines inthe asymmetric addition of organometallic reagents, Mannich-,aza-Henry, Strecker, and other asymmetric nucleophilic additionreactions. 1 Introduction 2 Asymmetric Mannich-Type Reactions 2.1 Phase-Transfer-Catalyzed Mannich Reactions 2.2 Bifunctional Organocatalyzed Mannich Reactions 3 Catalytic Enantioselective Addition of Organometallic Reagents- 4 Catalytic Enantioselective Aza-Henry Reactions 5 Asymmetric Strecker Reactions 6 Miscellaneous Reactions 7 Summary and Outlook
TL;DR: In this paper, an ordered mesoporous silica material MCM-41-SO3H, with covalently anchored sulfonic acid groups located inside the mesochannels, was used as an acid catalyst for the rapid and green synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives under a solvent-free condition.
Abstract: MCM-41-SO3H, ordered mesoporous silica material MCM-41
with covalently anchored sulfonic acid groups located inside the
mesochannels, was used as an acid catalyst for the rapid and ‘green’ synthesis
of 2,3-dihydroquinazolin-4(1H)-one derivatives under
solvent-free condition. This novel synthetic method offers several
advantages, such as excellent yields, simple procedure, short reaction
times, and mild reaction conditions.
TL;DR: A review with 272 references covers the literature publishedup to the end of February 2010 on the methods, other than the Mizoroki-Heckreaction, that have been developed in the last three decades to introduce carbon-carbon double bonds, frequently even ina stereocontrolled manner, onto heteroarene moieties by using transitionmetal-catalyzed reactions that do not involve the use of stoichiometric amountsof organometallic reagents as mentioned in this paper.
Abstract: This review with 272 references covers the literature publishedup to the end of February 2010 on the methods, other than the Mizoroki-Heckreaction, that have been developed in the last three decades tointroduce carbon-carbon double bonds, frequently even ina stereocontrolled manner, onto heteroarene moieties by using transition-metal-catalyzedreactions that do not involve the use of stoichiometric amountsof organometallic reagents. The practicality and versatility ofthese methods with respect to substrate scope and operational costsare discussed. 1 Introduction 2 N-Alkenylation Reactions of Free (NH)-Azoles with Alkenyl- Halidesor Pseudohalides 3 Direct C-Alkenylation Reactions of Heteroarenes with Alkenyl- Halides,Triflates, Phosphates, and 1,3-Dicarbonyl Compounds 4 Oxidative Coupling Reactions of Heteroarene C(sp 2 )-H Bondswith Alkenes and Decarboxylative Alkenylation Reactions- ofHeteroarenecarboxylic Acids with Alkenes 5 Addition of Heteroarene C(sp 2 )-H Bondswith Alkenes and Decarboxylative Alkenylation Reactions- ofHeteroarenecarboxylic Acids with Alkenes 5 Addition of Heteroarene C(sp 2 )-HBonds to Alkynes 6 Heteroarylcyanation of Alkynes 7 Conclusions
TL;DR: In this paper, a new and efficient procedure for the one-pot conversion of various alcohols, aldehydes and primary amines into the corre- sponding nitriles in excellent yields was easily achieved by trichloro- isocyanuric acid (TCCA) as an oxidant and reagent in aqueous ammonia.
Abstract: A new and efficient procedure for the one-pot conversion of various alcohols, aldehydes and primary amines into the corre- sponding nitriles in excellent yields was easily achieved by trichloro- isocyanuric acid (TCCA) as an oxidant and reagent in aqueous ammonia. Also, various benzylic halides were smoothly and direct- ly converted into the corresponding aromatic nitriles in high yields under the same conditions.
TL;DR: In this paper, a selection of carbon-fluorine bond-forming reactions with particular focus on transition metal-mediated fluorination is presented with a brief summary of conventional fluorination reactions.
Abstract: A selection of carbon–fluorine bond-forming reactions is presented with particular focus on transition metal-mediated fluorination. A brief summary of conventional fluorination reactions is followed by a discussion of fluorination reactions mediated by palladium and silver. Investigations into the mechanism as well as the conceptual difficulty associated with transition metal-mediated carbon–fluorine bond formation are presented.
TL;DR: In this paper, a microwave assisted, organocatalytic domino Michael/Henry condensation/Michael/aldol condensation reaction has been developed, employing acetaldehyde and nitroalkenes as substrates.
Abstract: A microwave-assisted, organocatalytic domino Michael/Henry condensation/Michael/aldol condensation reaction has been developed. Employing acetaldehyde and nitroalkenes as substrates, this quadruple cascade allows an efficient asymmetric synthesis of trisubstituted cyclohexene carbaldehydes in moderate to good yields (25-45%) and high enantioselectivities (ee = 89 to >99%). ESI-MS measurements were carried out to support the proposed complex catalytic cycle.
TL;DR: In this article, an efficient, one-pot, regioselective synthesis of 1,4-diaryl-1 H-1,2,3-triazoles is described via thecopper(I)-catalyzed reaction of diaryliodonium salts, sodium azide and terminal alkynes.
Abstract: An efficient, one-pot, regioselective synthesis of 1,4-diaryl-1 H-1,2,3-triazoles is described via thecopper(I)-catalyzed reaction of diaryliodonium salts, sodium azideand terminal alkynes. The generality of this protocol is demonstratedby the synthesis of a series of 1,4-diaryl-1 H-1,2,3-triazolesin good to high yields. The catalyst and reaction solvent are reusedwithout any appreciable reduction in product yield.
TL;DR: This review presents methods, most of them developed in the 21 st century, to mimic carbohydrates with a focus on their synthesis, and a wide range of different reactions are discussed in order to access carbohydrate-like structures.
Abstract: Highly diverse strategies are employed to mimic carbohydrates. Two subgroups of carbohydrate mimetics are very important: alterations of the core structure and modifications of the O-glycosidic linkage. This review presents methods, most of them developed in the 21 st century, to mimic carbohydrates with a focus on their synthesis. A wide range of different reactions are discussed in order to access carbohydrate-like structures. 1 Introduction 1.1 Scope of the Review 2 Core Modifications 2.1 Modifications of Functional Groups 2.1.1 Additional Alkyl Substituents 2.1.2 Fluorine Substituents 2.2 Seven-Membered Rings 3 Linkage Modifications 3.1 N-Glycosides 3.2 S-Glycosides 3.3 C-Glycosides 3.4 Peptoidic Bonds 4 Miscellaneous 5 Conclusion and Outlook.
TL;DR: In this article, a microwave-promoted protocol mediated by Mn(OAc) 3 was developed for the single-electron-transfer oxidative direct C-H bond arylation of (hetero)arenes with aryl and hetero-arylboronic acids.
Abstract: A novel microwave-promoted protocol mediated by Mn(OAc) 3 was developed for the single-electron-transfer oxidative direct C―H bond arylation of (hetero)arenes with aryl and hetero-arylboronic acids. Various electron-deactivated and electron-rich heteroarenes and benzene underwent successfully the direct arylation in this general process. The use of slight excess of heteroarene or benzene in this method was found to be sufficient.
TL;DR: In this article, a new mono-and bis(spiro-2-amino-4 H-pyrans) are synthesized by the multicomponent condensation reaction of 4-hydroxycoumarin and malononitrile with isatins, ninhydrin, 9,10-phenanthrenequinone, or acenaphthenequinone.
Abstract: Some new mono- and bis(spiro-2-amino-4 H-pyrans)are synthesized by the multicomponent condensation reaction of 4-hydroxycoumarinand malononitrile with isatins, ninhydrin, 9,10-phenanthrenequinone,or acenaphthenequinone. Alum was found to be a suitable and efficientcatalyst for this condensation.
TL;DR: In this article, a review of stereoselective methods for the preparation of halogenated carboxylic acids and amino acids is presented, focusing on halogen atom transfer processes and methods for synthesizing fluoroalkyl-substituted compounds.
Abstract: This review summarizes and focuses on stereoselective methodsfor the preparation of halogenated carboxylic acids and amino acids.Diastereoselective and enantioselective halogen atom transfer processesas well as methods for the synthesis of fluoroalkyl-substitutedcompounds are discussed in detail. 1 Introduction 2 Stereoselective Halogenation Reactions 2.1 Diastereoselective Transformations 2.2 Processes Employing Chiral Auxiliaries 2.3 Organocatalytic Methods 2.4 Chiral Halogenating Reagents 2.5 Halogenations with Chiral Lewis Acids 3 Stereoselective Fluoroalkylation 3.1 Nucleophilic Fluoroalkylations 3.1.1 Trifluoromethylations 3.1.2 Monofluoromethylations and Difluoromethylations 3.1.3 α-Fluoro-β-keto Esters as Nucleophiles 3.1.4 Difluoroacetate-Derived Nucleophiles 3.2 Radical Fluoroalkylations 3.3 Electrophilic Trifluoromethylation 3.4 Reactions of α-Trifluoromethyl-Substitituted Enolates 3.5 Nucleophilic Additions to Trifluoropyruvate 4 Concluding Remarks
TL;DR: The method described herein complements existing procedures for the preparation of aryl azides from the respective amino, triazene, and halide derivatives and it is expected that it will greatly facilitate copper- and ruthenium-catalyzed azide-alkyne cycloaddition reactions for the prepared of diversely functionalized 1-aryl- or 1-heteroaryl-1,2,3-triazoles derivatives.
Abstract: We report the copper(II)-catalyzed conversion of organoboron compounds into the corresponding azide derivatives. A systematic series of phenylboronic acid derivatives is evaluated to examine the importance of steric and electronic effects of the substituents on reaction yield as well as functional group compatibility. Heterocyclic substrates are also shown to participate in this mild reaction while compounds incorporating B-C(sp(3)) bonds are unreactive under the reaction conditions. The copper(II)-catalyzed boronic acid-azide coupling reaction is further extended to both boronate esters and potassium organotrifluoroborate salts. The method described herein complements existing procedures for the preparation of aryl azides from the respective amino, triazene, and halide derivatives and we expect that it will greatly facilitate copper- and ruthenium-catalyzed azide-alkyne cycloaddition reactions for the preparation of diversely functionalized 1-aryl- or 1-heteroaryl-1,2,3-triazoles derivatives.
TL;DR: In this article, a one-pot Friedlander quinoline synthesis with O-nitro-carbaldehydes and ketonesor aldehydes was developed and the scope and limitations of themethod were examined.
Abstract: A highly effective one-pot Friedlander quinoline synthesisfrom O-nitroarylcarbaldehydes and ketonesor aldehydes was developed and the scope and limitations of themethod were examined. The O-nitroarylcarbaldehydeswere reduced to O-aminoarylcarbaldehydeswith iron in the presence of a catalytic amount of aqueous hydrochloricacid; the amino compounds were then condensed in situ with ketonesor aldehydes to form mono- or disubstituted quinolines, respectively,in good-to-excellent yields (58-100%).
Abstract: Anions generated from primary arylamines react with substitutednitrobenzenes to form σ H -adducts, which, underbasic reaction conditions, undergo transformation to N-aryl-2-nitroso-amines. Competitivesubstitution of reactive halogens in the nitro-arenes,which is observed in certain cases, can be controlled by the solventselected.
TL;DR: The three-component reactions of phenacyl bromide or its derivatives, amine, and dialkyl acetylenedicarboxylate in the presence of iron(III) chloride as a catalyst at room temperature afforded polysubstituted pyrroles in high yields as mentioned in this paper.
Abstract: The three-component reactions of phenacyl bromide or its derivatives, amine, and dialkyl acetylenedicarboxylate in the presence of iron(III) chloride as a catalyst at room temperature afforded polysubstituted pyrroles in high yields.
TL;DR: Tris(pentafluorophenyl)borane has been found to be an effective catalyst for the alkylation of 1,3-dicarbonyl compounds using benzylic alcohols as alkylating agents.
Abstract: Tris(pentafluorophenyl)borane has found to be an effective catalyst for the alkylation of 1,3-dicarbonyl compounds using benzylic alcohols as alkylating agents. Various 1,3-dicarbonyl compounds reacted cleanly with different benzylic alcohols to provide the corresponding monoalkylated products in good yield. In addition tris(pentafluorophenyl)borane efficiently promoted the C3 alkylation of 4-hydroxycoumarins. Further, several oxygenated heterocycles such as furans, 4H-chromenes, and furanocoumarins have been prepared using the described methodology as the key step.
TL;DR: In this article, a series of 1-allylated and 1-benzylated 1,2,3-triazoles with varying substituents at the 4 position were prepared in yields ranging from 74-98% using a two-step one-pot click transformation.
Abstract: A series of 1-allylated and 1-benzylated 1,2,3-triazoles with varying substituents at the 4-position were prepared in yields ranging from 74—98% using a two-step one-pot click transformation. This tandem reaction involved the nucleophilic substitution of allyl chloride and benzyl bromide with sodium azide to form organic azide intermediates followed by Cu-catalyzed Huisgen 1,3-dipolar cycloaddition with alkyne reactants in a single reaction pot without the need for sequentially separating reaction steps. 1-Allyl-and 1-benzyl-4-alkyl-1,2,3-triazoles possessing linear alkyl chains underwent efficient N-alkylation at the 3-position with methyl iodide, while tert-butyl and phenyl derivatives did not. Each of the 1-allyl- and 1-benzyl-3-methyl-4-alkyl-1,2,3-triazolium iodide salts prepared was a viscous liquid at room temperature with a stable shelf life.