Aldehyde Alkyne Research Articles

Electrochemical Esterification Reaction of Alkyne Aldehyde with Alcohols Mediated by Carbene and Iodine

A new type of alkyne esterification was developed under electrochemical conditions using alkyne aldehydes and alcohol compounds as starting materials and carbene and iodine as mediators. Through this method, external oxidants and transition metals are excluded and the alkyne bond is fully preserved. This approach is compatible with a wide range of substrates and various functional groups and provides a green and mild new route for directly converting alkyne aldehydes into alkyne esters.

A Catalytic Intramolecular Aldehyde–Alkyne Metathesis Approach to Azepino[1,2‐a]indoles

Reported herein is a method for the construction of azepino[1,2‐a]indoles via an intramolecular aldehyde–alkyne metathesis of 1‐(5‐aryl‐4‐pentynyl)indole‐2‐carbaldehydes. This Sc(OTf)3‐catalyzed reaction has several remarkable features, such as ready accessibility of the starting materials, broad substrate scope, operational simplicity, and high yields. The practicality of the process and the synthetic potential of the products were demonstrated with an upscaling experiment and downstream synthetic derivatizations of the obtained products. We have also extended this methodology to synthesize a 6,7‐dihydropyrido[1,2‐a]indole derivative.

Encapsulation of mixed-valence copper oxide nanoparticles in aluminum carboxymethylcellulose composite microspheres: an efficient synergistic catalyst for boosting aldehyde–alkyne–amine coupling reactions

Encapsulation of mixed-valence copper oxide nanoparticles in aluminum carboxymethylcellulose composite microspheres: an efficient synergistic catalyst for boosting aldehyde–alkyne–amine coupling reactions

Thiamine carbene liganded gold(i) chloride catalyzes an efficient aldehyde–alkyne–amine coupling reaction in water

Thiamine (vitamin B1) carbene liganded gold(i) chloride efficiently catalyses an aldehyde–alkyne–amine (A3) coupling reaction in open air under solvent-free conditions or in water.

DFT mechanistic study on nickel/IPr‐catalyzed aldehyde–alkyne reductive couplings with trialkylsilane/dialkylsilane

AbstractDensity functional theory calculations were carried out to reveal the mechanistic details of aldehyde–alkyne reductive couplings with trialkylsilane/dialkylsilane. The reaction with trialkylsilane is found to proceed through oxidative cyclization, Si‐H/Ni‐O σ‐bond metathesis, and C(sp2)‐H reductive elimination, leading to silylated allylic alcohols. The steric hindrance between the n‐pent group of alkyne and iPr group of the NHC ligand determines the regioselectivity. While for the reaction with dialkylsilane, the present calculations propose a new mechanism, which consists of oxidative cyclization, Si−H/Ni−O σ‐bond metathesis, Ni−C/Si−H σ‐bond metathesis, and dehydrogenation, resulting in oxasilacyclopentenes. The calculated energy profiles rationalize the experimentally observed chemodivergence.

Spray-Assisted Interfacial Polymerization to Form CuII/I@CMC-PANI Film: An Efficient Dip Catalyst for A3 Reaction.

A novel and interesting method for the preparation of carboxymethylcellulose–polyaniline film-supported copper catalyst (CuII/I@CMC-PANI) has been developed via spray-assisted interfacial polymerization. Using copper sulfate as an initiator, spraying technology was introduced to form a unique interface that is perfectly beneficial to the polymerization of aniline monomers onto carboxymethylcellulose macromolecule chains. To further confirm the composition and structure of the as-prepared hybrid film, it was systematically characterized by inductively coupled plasma (ICP), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and thermogravimetric analysis (TGA) techniques. The Cu content in the fresh CuII/I@CMC-PANI film was determined to be 1.805 mmol/g, and spherical nanoparticles with an average size of ca. 10.04 nm could be observed in the hybrid film. The CuII/I@CMC-PANI hybrid film was exerted as a dip catalyst to catalyze the aldehyde–alkyne–amine (A3) coupling reactions. High yields of the products (up to 97%) were obtained in this catalytic system, and the catalyst could be easily picked up from the reaction mixture by tweezers and reused for at least six consecutive runs, without any discernible losses in its activity in the model reaction. The dip catalyst of CuII/I@CMC-PANI, with easy fabrication, convenient deployment, superior catalytic activity, and great reusability, is expected to be very useful in organic synthesis.

A green approach for A3-coupling reactions: an experimental and theoretical study on NHC silver and gold catalysts

N-heterocyclic carbene silver and gold complexes active in A3-coupling (aldehyde–alkyne–amine) reactions in green conditions.

New NHC- silver and gold complexes active in A3-coupling (aldehyde-alkyne-amine) reaction

Silver and gold complexes bearing unsaturated N-heterocyclic carbene ligands, with unsymmetrical N-substituents and hydrogen or chlorine on backbone, have been synthetized and their efficiency tested in A3-coupling (aldehyde–alkyne–amine) reactions. Gold complexes showed higher activity than corresponding silver ones, even if the significant role of the backbone substituents should not be neglected. Indeed, complexes with chlorine substituted backbone were more efficient than hydrogen analogous. According to DFT calculations, electronic differences among complexes are able rationalize the different catalytic behavior, whereas steric properties play a minor part.

Asymmetric total synthesis of filamentous fungi related resorcylic acid lactones 7-epi-zeaenol and zeaenol

AbstractAn efficient, short and, a convenient asymmetric total synthesis of filamentous fungi related resorcylic acid lactones 7-epi-zeaenol (2) and zeaenol (1) have been achieved in 7 and 9 linear steps with the high overall yield of 32% and 21% respectively, from the known intermediate 13. Mitsunobu inversion, De Brabander’s protocol for macrolactonisation, Heck cross-coupling, diastereoselective alkyne aldehyde coupling and Ohira–Bestmann alkynylation are the key reactions.

The Asymmetric A³(Aldehyde⁻Alkyne⁻Amine) Coupling: Highly Enantioselective Access to Propargylamines.

The recent developments in asymmetric A3 (aldehyde–alkyne–amine) coupling has been summarized in this review. Several interesting modifications of the ligands enabled the highly enantioselective synthesis of chiral propargylamines, which are further used in the construction of nitrogen-containing chiral building blocks.

Copper-Based Bulk and Nano-Catalysts for the One-Pot Propargylamine Synthesis

Propargylamines are prominent components strikethrough as precursors for the synthesis of miscellaneous nitrogen-containing compounds, such as allylamines, pyrrolidines, pyrroles and oxazoles or as intermediates in the preparation of a various natural product, biologically active and pharmaceutical compounds. The catalytic coupling of the aldehyde–alkyne–amine (A3 coupling) has shown great utility in the simple and rapid preparation of propargylamines in broadly tolerant and highly tunable reaction conditions. In this respect, various catalytic systems using transition metal catalysts have been developed. Based on a literature survey, Cu catalysts have promoted this field substantially via development of new methods for the synthesis of propargylamines. This review will cover copper-based catalyst system reported for the synthesis of propargylamine derivatives until 2017.

A comparative study on atomically precise Au nanoclusters as catalysts for the aldehyde-alkyne-amine (A3) coupling reaction: ligand effects on the nature of the catalysis and efficiency.

Atomically precise Au13 nanoclusters stabilized by stibines catalyze the aldehyde–alkyne–amine coupling reaction more efficiently than those stabilized by thiols or phosphines. The nature of the catalytic activity is also different, and may be attributed to the weaker coordinating ability of the stibine ligands.

Boron trifluoride–etherate in fluorinated alcohols: A powerful promoter system for intramolecular alkyne–aldehyde metathesis of o-(3-arylpropargyloxy)benzaldehydes

Boron trifluoride–etherate (BF3·OEt2) in 2,2,2‐trifluoroethanol (TFE) was found to be a highly efficient promoter system for the intramolecular alkyne–aldehyde metathesis of o-(3-arylpropargyloxy)benzaldehydes. The reaction produces the corresponding 3-aroyl-2H-chromenes in excellent yields under metal-free conditions.

Synthesis of Polyquinolines via One-Pot Polymerization of Alkyne, Aldehyde, and Aniline under Metal-Free Catalysis and Their Properties

A novel synthetic route to polyquinolines with 6-substituted quinoline as the structural unit was developed based on the polymerization of alkyne–aldehyde monomers and aniline derivatives under the catalysis of Lewis acid B(C6F5)3. The polymerization was conducted in dichloroethane at 100 °C for 36 h under air atmosphere, affording polyquinolines with molecular weights up to 13 100 and good solubility in most organic solvents. The substituents in aniline exhibited significant effects on the molecular weight, yield, and solubility of the produced polyquinolines. The structures of prepared polymers were characterized and confirmed by GPC, NMR, and FT-IR. The thermogravimetry (TGA) and differential scanning calorimetry (DSC) analysis suggests that the polyquinolines are highly thermal stable. Further photoluminescence behaviors of the prepared polyquinolines were investigated. Based on the characterization results and small molecule reaction mechanism, the polymerization pathway of the polyquinolines was pro...

Cu3L2 metal-organic cages for A3-coupling reactions: reversible coordination interaction triggered homogeneous catalysis and heterogeneous recovery.

The reported Cu(ii) metal-organic cage (Cu3L2, 1) can be a highly active reusable catalyst to homogeneously catalyze the A3-coupling reaction in CHCl3 and can be heterogeneously recovered by simply adding 1,4-dioxane via formation of the insoluble metal-organic framework (Cu3L2(1,4-dioxane)1.5, 2).

Utilization of CO2 as a C1 Building Block in a Tandem Asymmetric A3 Coupling-Carboxylative Cyclization Sequence to 2-Oxazolidinones

We report a tandem asymmetric aldehyde–alkyne–amine (A3) coupling-carboxylative cyclization sequence for the highly enantioselective synthesis of chiral N-aryl 2-oxazolidinones. This is a rare example of a multicatalyst-promoted asymmetric tandem reaction using CO2 as a C1 synthon. Notably, the copper species and ligand from the upstream A3 reaction are internally reused to facilitate the downstream silver-catalyzed carboxylative cyclization.

Iron-Catalyzed Intramolecular Alkyne–Carbonyl Metathesis: A New Cyclization Strategy for the Synthesis of Benzocarbazole and Azepino[1,2-a]indole Derivatives

An efficient synthesis of benzocarbazoles and benzo[3,4]azepino[1,2-a]indole derivatives through an FeCl3-catalyzed alkyne–aldehyde metathesis reaction is described. Structurally diverse benzo[a]carbazoles, benzo[c]carbazoles, and benzo[3,4]azepino[1,2-a]indoles have been achieved in good yields with high regio- and chemoselectivity in the presence of catalytic, inexpensive, and environmentally friendly FeCl3­ as a catalyst.

Cycloaurated Phosphinothioic Amide Complex as a Precursor of Gold(I) Nanoparticles: Efficient Catalysts for A3 Synthesis of Propargylamines under Solvent-Free Conditions

A C,S-cycloaurated complex based on an ortho-substituted phosphinothioic amide framework has been synthesized in high yield through tin(IV)–Au(III) transmetalation from the corresponding chlorodimethylstannyl derivative. The latter was prepared in a two-step process involving directed ortho lithiation/quenching with Me3SnCl followed by Me/Cl exchange. The tin(IV) and gold(III) complexes have been characterized in solution and in the solid state. In both complexes, the phosphinothioic amide moiety acts as a C–C–P–S pincer ligand with formation of five-membered-ring metalacycles. The use of the gold(III) complex in the amine–aldehyde–alkyne (A3) three-component coupling synthesis of propargylamines showed that the compound is transformed into the Sonogashira-type o-alkynylphosphinothioic amide with generation of Au(I) nanoparticles with an average size of around 7 nm. These nanoparticles proved to be excellent catalysts in A3 coupling processes, providing propargylamines in high yields under solvent-free co...

ChemInform Abstract: Copper Catalyzed Aerobic Oxidative Cyclization and Ketonization: One Pot Synthesis of Benzoimidazo[1,2‐a]imidazolones.

AbstractAlkylaldehydes and ‐acetylenes are non‐feasible substrates for this method.

Impact of Ligand and Silane on the Regioselectivity in Catalytic Aldehyde–Alkyne Reductive Couplings: A Theoretical Study

The reaction mechanisms of the (NHC)Ni(0)-catalyzed aldehyde–alkyne reductive couplings with silanes as reducing agent have been theoretically investigated with the aid of DFT calculations. The impacts of N-heterocyclic carbene (NHC) ligands and silanes on the reversal of regioselectivity and the rate-limiting step alteration were rationalized. It is found that the steric effects play a dominant role. The reversal of the regioselectivity is found to be related to the switching of the steric effect, from the aldehyde phenyl hindrance with the adjacent alkyne substituent to the NHC ligand hindrance with the adjacent alkyne substituent, when the NHC ligand employed is changed from small to large. The rate-limiting step alteration caused by using bulkier silanes is due to the generated strong steric effect, which makes the σ-bond metathesis transition state relatively high in enthalpic energy, thus with the entropy penalty making the metathesis step rate-limiting instead of the oxidative cyclization step.