Electron-deficient Alkynes Research Articles

Ring expansion of a 2-rhodaoxetane: insertion chemistry with unsaturated molecules

A 2-rhodaoxetane was found to react with unsaturated electrophiles, such as highly electron-deficient acetylene dicarboxylates, CS2 and various aldehydes, to form a series of six-membered metallacycles. These metallacycles were characterized by (1)H, (13)C and 2D NMR spectroscopic techniques, as well as HRMS and, for one complex, XRD. In some cases, the insertions were found to be reversible.

Photochemical Intermolecular Silylacylations of Electron-Deficient Internal Alkynes

Light-induced Brook rearrangements of acylsilanes facilitate silylacylation reactions of electron-deficient internal alkynes. A wide range of aromatic substituents on the acylsilane aryl group are tolerated, affording a series of functionalized enonyl silanes. The presence of electron-withdrawing substituents on the alkyne is crucial for the success of the addition process.

Fast and Green One-Pot Multicomponent Synthesis of a Library of Pyrrolo[1,2-c] Pyrimidines Under Microwave Irradiation

A simple, clean and rapid one-pot three component, microwave-assisted synthesis of pyrrolo[1,2-c]pyrimidine derivatives starting from various substituted pyrimidines, 2-bromoacetophenones and nonsymmetrical, electron deficient alkynes in 1,2-epoxybutane which acts both as solvent and acid scavenger is reported. This one-pot three component synthesis implies short reaction times being at the same time highly cost-effective and environmental friendly.

Phosphine‐Catalyzed [3+2] Annulation of Electron‐Deficient Alkynes with N‐Hydroxyphthalimide: Synthesis of 3a‐Hydroxyisoxazolo[3,2‐a]isoindol‐8(3aH)‐ones

AbstractThe phosphine‐catalyzed [3+2] annulation of electron‐deficient alkynes with N‐hydroxyphthalimide has been developed to give a variety of pharmaceutically attractive 3a‐hydroxyisoxazolo[3,2‐a]isoindol‐8(3aH)‐ones in good to excellent yields.magnified image

Gold-catalyzed reaction of oxabicyclic alkenes with electron-deficient terminal alkynes to produce acrylate derivatives

Oxabicyclic alkenes can react with electron-deficient terminal alkynes in the presence of a gold catalyst under mild conditions, affording the corresponding addition products in moderate yields. When using alkynyl esters as substrates, the (Z)-acrylate derivatives are obtained. Using but-3-yn-2-one (ethynyl ketone) as a substrate, the corresponding addition product is obtained with (E)-configuration. The proposed mechanism of these reactions is also discussed.

Microwave-Promoted Efficient Synthesis of Benzo[h]quinolines by Solvent-Free Three-Component Imino-Diels-Alder Reaction under One-Pot Condi­tions

An one-pot, solvent-free imino Diels–Alder reaction has been developed under microwave conditions using 1-naphthylamine, aldehydes, and electron-deficient terminal alkynes in the presence of a catalytic amount of In(OTf)3 for construction of benzo[h]quinoline derivatives in short reaction times. The method is clean and operationally simple.

Efficient synthesis of indolizines and new imidazo[1,2-a]pyridines via the expected cyclization of aromatic cycloimmonium ylides with electron deficient alkynes and ethyl cyanoformate

Aromatic cycloimmonium ylides underwent smooth cyclization with electron deficient alkynes in presence of anhydrous K2CO3 in DMF solvent at room temperature to afford substituted indolizines. Ylides have also undergone expected cyclization with ethyl cyanoformate to produce imidazo[1,2-a]pyridines. The structures of these newly synthesized compounds have been confirmed by spectroscopic techniques and X-ray diffraction studies.

Mechanistic Origin of Chemo- and Regioselectivity of Nickel-Catalyzed [3 + 2 + 2] Cyclization Reaction

A density functional theory (DFT) study was performed to elucidate the mechanism of the Ni-catalyzed [3 + 2 + 2] cyclization reaction of cyclopropylideneacetate with two alkynes. A systematic search showed that the nature of the alkynes determines the choice between two reaction pathways and hence the regioselectivity. Strongly electron-deficient acetylenes preferentially afford 2,5-disubstituted products via nickelacyclopentadienes generated by [2 + 2] cocyclization, whereas normal alkynes afford 3,4- or 3,5-products via an unprecedented pathway involving a [3 + 2] nickelacycle intermediate.

Synthesis of some novel fluoro isoxazolidine and isoxazoline derivatives using N-benzyl fluoro nitrone via cycloaddition reaction in ionic liquid

1-Butyl-3-methylimidazolium-based ionic liquids are found to accelerate significantly the intermolecular 1,3-dipolar cycloaddition of N-benzyl-fluoro nitrone derived in situ from 2,6-difluoro benzaldehyde and N-benzylhydroxylamine, with activated alkenes and electron deficient alkynes to afford enhanced rates and improved yields of novel isoxazolidines and isoxazolines. 1-Butyl-3-methylimidazolium-based ionic liquids are found to accelerate significantly the intermolecular 1,3-dipolar cycloaddition of N-benzyl-fluoro nitrone derived in situ from 2,6-difluoro benzaldehyde and N-benzylhydroxylamine, with activated alkenes and electron deficient alkynes to afford enhanced rates and improved yields of novel isoxazolidine, isoxazolines.

ChemInform Abstract: Construction of Spiro[indoline]oxindoles Through One‐Pot Thermal‐Induced [3 + 2] Cycloaddition/Silica Gel‐Promoted Fragmentation Sequence Between Isatin Ketonitrones and Electron‐Deficient Alkynes.

One-pot thermal-induced [3+2] cycloaddition/silica gel-promoted fragmentation sequence between isatin ketonitrones and electron-deficient alkynes affords spiro[indoline]oxindoles in moderate to excellent yields along with good diastereoselectivities. The detailed mechanism of silica gel-promoted fragmentation has been clarified by experiment and DFT calculations.

A new route to the synthesis of isoxazoline derivatives from dihydropyran via cycloaddition reaction in ionic liquid

A new approach to the synthesis and 1,3-dipolar cycloadditions of nitrones has been described from 2,3-dihydro-4H-pyran and various hydroxylamines, with electron-deficient alkynes for the synthesis of isoxazoline derivatives. Significant rate acceleration and improved yields of exclusively exo isoxazolines in 1-butyl-3-methylimidazolium based ionic liquids have been observed. Novel isoxazolines may be used as a precursor for the synthesis of variety of peptides.

First example of the synthesis of pyrrolecarbaldehyde with electron-deficient acetylene substituents

First example of the synthesis of pyrrolecarbaldehyde with electron-deficient acetylene substituents

Stereoselective Tandem Ring Opening of Imidazoles with Electron-Deficient Acetylenes and Water: Synthesis of Functionalized (Z,Z)-1,4-Diaza-2,5-dienes

1-Substituted imidazoles undergo exceptionally facile stereoselective ring opening under the influence of electron-deficient acetylenes and water (equimolar ratio of the reactants) in MeCN at 45-60 °C without any catalysts to afford functionalized (Z,Z)-1,4-diaza-2,5-dienes, (Z,Z)-propenylaminoethenylformamides, in up to 80% yields. The reaction is rationalized to proceed in a tandem manner via zwitterionic vinyl carbanions formed by nucleophilic addition of imidazole to the triple bond. The carbanionic center is then quenched with water followed by the rearrangement of the intermediate 2-hydroxy-3-alkenylimidazolines.

Gold-Catalyzed Benzannulation of Electronically Rich/Rich and Deficient/Deficient Oxoalkynes with Alkynes

Two different strategies have been developed to perform the gold-catalyzed benzannulation of both electron-rich pyridine containing oxoalkynes with electron-rich alkynes as well as electron-deficient pyridine containing oxoalkynes with electron-deficient­ alkynes. The benzannulation between electron-rich oxoalkynes with electron-rich alkynes proceeds in the presence of highly electron-deficient gold catalysts, whereas using catalytic amount of alcohol benzannulation was performed efficiently between electron-deficient oxoalkynes with electron-deficient alkynes.

Construction of spiro[indoline]oxindoles through one-pot thermal-induced [3+2] cycloaddition/silica gel-promoted fragmentation sequence between isatin ketonitrones and electron-deficient alkynes

One-pot thermal-induced [3+2] cycloaddition/silica gel-promoted fragmentation sequence between isatin ketonitrones and electron-deficient alkynes affords spiro[indoline]oxindoles in moderate to excellent yields along with good diastereoselectivities. The detailed mechanism of silica gel-promoted fragmentation has been clarified by experiment and DFT calculations.

Asymmetric Conjugated Addition to Electron-Deficient Alkynes

Key words conjugate addition - oxindoles - electron-deficient alkynes - tertiary-amine urea

Organocatalytic, Regioselective Nucleophilic “Click” Addition of Thiols to Propiolic Acid Esters for Polymer–Polymer Coupling

Discerning Tastes: The regioselectivity of the nucleophilic addition of thiols to electron-deficient alkynes is controlled by the choice of the solvent (i.e. the polarity of the reaction mixture) and the catalyst. Both thioalkenes and dithianes can be prepared in a rapid reaction that generates no by-products (see scheme). In turn the utility of this reaction is shown for efficient end-group modification of polymers. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Hypervalent iodine(iii)-induced oxidative [4+2] annulation of o-phenylenediamines and electron-deficient alkynes: direct synthesis of quinoxalines from alkyne substrates under metal-free conditions

Hypervalent iodine(III)-induced oxidative [4+2] annulation of o-phenylenediamines and electron-deficient alkynes under metal-free conditions has been developed. The reaction allows for direct access to quinoxalines bearing two electron-withdrawing groups in an efficient manner.

Microwave-assisted multicomponent diastereoselective 1,3-dipolar cycloaddition of ethyl glyoxylate derived azomethine ylides

The thermal multicomponent 1,3-dipolar cycloaddition (1,3-DC) of diethyl aminomalonate or α-amino esters (derived from glycine, alanine, phenylalanine, and phenylglycine) with ethyl glyoxylate and the corresponding dipolarophile such as maleimides, methyl acrylate, methyl fumarate, (E)-1,2-bis(phenylsulfonyl)ethylene, and electron deficient alkynes allows the diastereoselective synthesis of new polysubstituted pyrrolidine derivatives. Microwave-assisted heating processes give better results than conventional heating ones, affording endo-cycloadducts as major stereoisomers. In general, 2,5-cis-cycloadducts are preferentially formed according to the previous formation of the W-shaped dipole. Only in the 1,3-DC of the disulfone with phenylglycine and ethyl glyoxylate the corresponding exo-trans-cycloadduct was isolated. The compound endo-cis-4b, derived from phenylalanine, ethyl glyoxylate and N-benzylmaleimide, has been further transformed into a very complex diazabicyclo[2.2.1]octane skeleton with potential biological activity.

DABCO-promoted synthesis of pyrazoles from tosylhydrazones and nitroalkenes

An efficient synthesis of pyrazoles from tosylhydrazones and nitroalkenes was developed. In comparison with the previously reported 1,3-dipolar cycloaddition reaction of diazo compounds with electron-deficient alkenes or alkynes, this methodology proceeded with a sequential Baylis-Hillman/intramolecular cyclization mechanism and a variety of reversed regioselectivity products were prepared in good yields.