Reaction Of Terminal Alkynes Research Articles

Titanocene-catalyzed selective synthesis of 2,4-dialkyl-6-(2-methoxyethyl)pyridines by the reaction of terminal acetylenes with 3-methoxypropionitrile

Titanocene-catalyzed selective synthesis of 2,4-dialkyl-6-(2-methoxyethyl)pyridines by the reaction of terminal acetylenes with 3-methoxypropionitrile

Unraveling Enyne Bonding via Dehydrogenation–Hydrogenation Processes in On‐Surface Synthesis with Terminal Alkynes

AbstractOn‐surface reactions of terminal alkynes in ultrahigh vacuum have attracted widespread attention due to their high technological promise. However, employing different precursors and substrate materials often intricate reaction schemes appear far from being well‐understood. Thus, recent investigations of alkyne coupling on noble metal surfaces suggest non‐dehydrogenative scenarios, contradicting earlier reports. Herein, the study employs noncontact atomic force microscopy (nc‐AFM) with high spatial resolution to conclusively characterize exemplary alkyne coupling products. Contrary to initial interpretations proposing dehydrogenative homocoupling on Ag(111), bond‐resolved AFM imaging reveals the expression of enyne motifs. Based on complementary, extensive density functional theory calculations, the pertaining reaction mechanisms are explored. It is proposed that enyne formation initiates with a direct carbon–carbon coupling between two alkyne groups, followed by surface‐assisted dehydrogenation‐hydrogenation processes. Thereby consecutive steps of atomic hydrogen cleavage, surface migration and recombination to a different carbon atom enable bridging via carbon–carbon double bonding. The new results shed light on subtle, but crucial surface‐mediated hydrogen transfer processes involved in the chemical bond formation, which are suggested to be of general relevance in on‐surface synthesis.

Divergent Reactivity of a Cyclic Bis-Hydridostannylene: A Masked Sn(I) Diradicaloid.

Herein, reactivity studies of a cyclic bis-hydridostannylene [(ADC)SnH]2 (1-H2) (ADC=PhC{(NDipp)C}2; Dipp=2,6-iPr2C6H3) with various unsaturated organic substrates are reported. Reactions of terminal alkynes (RC≡CH) with 1-H2 afford mixed acetylide-vinyl-functionalized bis-stannylenes via dehydrogenation and hydrostannylation. Treatment of 1-H2 with PhC≡CCH3 gives a unique distannabarrelene via dehydrogenative C(sp3)-H stannylation and hydrostannylation of the C≡CCH3 moiety. 1-H2 undergoes dehydrogenative [2+2]-cycloaddition reactions with diphenylacetylene, azobenzene, acetone, benzophenone, and benzaldehyde to form the 1,4-distannabarrelene derivatives. The elimination of H2 in these reactions suggests the masked-diradical property of 1-H2. In fact, these [2+2]-cycloaddition products are also accessible on treatments of the Sn(I) diradicaloid [(ADC)Sn]2 (1) with appropriate reagents. All compounds have been characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction. Moreover, the catalytic activity of 1-H2 has been shown for the hydroboration of unsaturated substrates.

Synthesis and characterization of a new copper-based polyoxomolybdate and its catalytic activity for azide-alkyne cycloaddition reaction under UV light irradiation

A new organic-functionalized Cu-based Anderson-type polyoxomolybdate, namely (C7H15N4)2[Na(H2O)4]2[C6H12CuMo6N2O24]·2(H2O) (CuII-POM), was synthesized via a simple one-pot reaction and subsequently characterized using a range of analytical and spectral techniques. Structural investigation by single crystal X-ray diffraction analysis revealed that the polyanion component of the synthesized compound (i.e. [C6H12CuMo6N2O24]4−) possesses a δ-isomer Anderson-type structure, which is surrounded by four lattice water molecules and four [C7H15N4–NaH15(H2O)8]4+ cations in the crystal packing arrangement. The resulting double-sided tris-functionalized Anderson-type compound can function as highly effective heterogeneous photocatalysts for the copper(I)-catalyzed Huisgen azide-alkyne cycloaddition (Cu-AAC) reaction of terminal alkyne, benzyl halides, and sodium azide (acts as the azidonation and reducing agent) in aqueous media. Ultraviolet light irradiation enhances the catalytic activity of CuII-POM ~ 4.4 times of the “off” situation under reaction conditions of 0.00239 mmol cat., 80 °C, 8 h, 2 mL H2O, So that the isolated yields for the AAC reaction involving a variety of terminal alkynes and benzyl halides using the CuII-POM catalyst ranged between 19–97%. The current study is the first report about using an efficient and economical Cu(II)-POM/UV/NaN3 catalytic system in the Cu-AAC reaction and reveals its significant potential for applying to other Cu(I)-catalyzed reactions.

Stereoselective Synthesis of Functionalized 1,3‐Enynes through Recyclable Copper(I)‐Catalyzed Three‐Component Reaction of Terminal Alkynes, Diazoesters and Aldehydes

AbstractA highly efficient heterogeneous copper(I)‐catalyzed three‐component coupling of terminal alkynes, diazoesters and aldehydes has been achieved by using 10 mol% of copper(I) iodide complex [N,N‐CuI‐MCM‐41] anchored on 2‐aminoethylamino‐modified mesoporous material MCM‐41 as the catalyst under mild conditions, delivering a wide variety of 2‐alkoxycarbonyl‐substituted (E)‐1,3‐enynes in mostly good to high yields with excellent stereoselectivity. The heterogenized copper(I) complex can be facilely prepared from inexpensive reagents by using a simple procedure and exhibits a remarkably higher catalytic activity than CuI, and can be recycled more than ten times without a significant drop in its catalytic efficiency. This protocol represents the first example of heterogeneous copper‐catalyzed stereoselective construction of functionalized 1,3‐enynes from simple and commercially available starting materials.

Photo-induced decarboxylative hydroacylation of α-oxocarboxylic acids with terminal alkynes by radical addition–translocation–cyclization in water

A photo-induced radical addition–translocation–cyclization (RATC) reaction of terminal alkynes and α-oxocarboxylic acids using water as the reaction medium is reported herein.

Synthesis of α-alkynyl perfluoroalkyl sulfoxides by the reaction of terminal alkynes and perfluoroalkanesulfinyl chlorides

The reaction of terminal alkynes with perfluoroalkanesulfinyl chlorides was achieved in the presence of n -BuLi/ZnCl 2 . A series of α-alkynyl perfluoroalkyl sulfoxides were synthesized for the first time in moderate to good yields via the nucleophilic substitution reaction of alkynylzinc chlorides formed in situ with perfluoroalkanesulfinyl chlorides. • The reaction of terminal alkynes with perfluoroalkanesulfinyl chlorides was firstly achieved. • α-Alkynyl perfluoroalkyl sulfoxides were synthesized for the first time. • Structurally diverse α-alkynyl perfluoroalkyl sulfoxides were obtained in good yields.

Reactions of diborenes with terminal alkynes: mechanisms of ligand-controlled anti-selective hydroalkynylation, cycloaddition and C[triple bond, length as m-dash]C triple bond scission.

The reactions of terminal acetylenes with doubly Lewis base-stabilised diborenes resulted in different outcomes depending on the nature of the ligands at boron and the conformation of the diborene (cyclic versus acyclic). N-heterocyclic carbene (NHC)-stabilised diborenes tended to undergo anti-selective hydroalkynylation at room temperature, whereas [2 + 2] cycloaddition was observed at higher temperatures, invariably followed by a C–N bond activation at one NHC ligand, leading to the ring-expansion of the initially formed BCBC ring and formation of novel boron-containing heterocycles. For phosphine-stabilised diborenes only [2 + 2] cycloaddition was observed, followed by a rearrangement of the resulting 1,2-dihydro-1,2-diborete to the corresponding 1,3-isomer, which amounts to complete scission of both the B Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> B double and CC triple bonds of the reactants. The elusive 1,2-isomer was finally trapped by using a cyclic phosphine-stabilised diborene, which prevented rearrangement to the 1,3-isomer. Extensive density functional theory (DFT) calculations provide a rationale for the selectivity observed.

Front Cover Picture: Zinc/Indium Bimetallic Lewis Acid Relay Catalysis for Dehydrogenative Silylation/Hydrosilylation Reaction of Terminal Alkynes with Bis(hydrosilane)s (Adv. Synth. Catal. 19/2020)

Front Cover Picture: Zinc/Indium Bimetallic Lewis Acid Relay Catalysis for Dehydrogenative Silylation/Hydrosilylation Reaction of Terminal Alkynes with Bis(hydrosilane)s (Adv. Synth. Catal. 19/2020)

Synthesis, characterization and biological activities of sulfonamide tagged 1,2,3-triazoles

The present paper elicits a marvelous synthesis of a series of sulfonamide containing 1,4-disubstituted 1,2,3-triazoles through click reaction of terminal alkynes with aromatic azides. The synthesized triazoles were characterized by FTIR, 1H NMR,13C NMR and HRMS techniques. Further, the structures of synthesized compounds 6u (CCDC 1954932) and 6z3 (CCDC 1954931) were also confirmed by X-ray crystallography. The synthesized triazoles were evaluated for in vitro antibacterial activity against S. aureus, B.subtilis, E. coli and K. pneumoniae by serial dilution method. Among the series, compound 4-bromo-N-(2-(1-(4-bromophenyl)-1H-1,2,3-triazol-4-yl)propan-2-yl)benzenesulfonamide, 6z4 (MIC = 0.025 µM/mL) and 4-bromo-N-(2-(1-(naphthalen-1-yl)-1H-1,2,3-triazol-4-yl)propan-2-yl)benzenesulfonamide 6z6 (MIC = 0.027 µM/mL) exhibited the appreciable antibacterial activity against Staphylococcus aureus and Bacillus subtilis. Further, the molecular docking studies of above potent analogs with dihydropteroate synthase was performed to have an insight for binding interactions. Synthesized molecules were also explored for antioxidant activity, reflecting compound 6m as better radical scavenging agent with IC50 value of 1.96 µM/mL.

Zinc/Indium Bimetallic Lewis Acid Relay Catalysis for Dehydrogenative Silylation/Hydrosilylation Reaction of Terminal Alkynes with Bis(hydrosilane)s

AbstractWhen mixed with two different Lewis acid catalysts of zinc and indium, terminal alkynes were found to react with bis(hydrosilane)s to selectively provide 1,1‐disilylalkenes from among several possible products, by way of a sequential dehydrogenative silylation/intramolecular hydrosilylation reaction. Adding a pyridine base is crucial in this reaction; a switch as a catalyst of the zinc Lewis acid is turned on by forming a zinc−pyridine‐base complex. A range of the 1,1‐disilylalkenes can be obtained by a combination of aryl and aliphatic terminal alkynes plus aryl‐, heteroaryl‐, and naphthyl‐tethered bis(hydrosilane)s. The 1,1‐disilylalkene prepared here is available as a reagent for further transformations by utilizing its C−Si or C=C bond. The former includes Hiyama cross‐coupling, bismuth‐catalyzed ether formation, and iododesilylation; the latter includes double alkylation and epoxidation. Mechanistic studies clarified the role of the two Lewis acids: the zinc–pyridine‐base complex catalyzes the dehydrogenative silylation as a first stage, and, following on this, the indium Lewis acid catalyzes the ring‐closing hydrosilylation as a second stage, thus leading to the 1,1‐disilylalkene.magnified image

Catalytic synthesis of dihydropyridines by domino reaction of terminal alkynes, carbodiimides, and acetylenic esters

A novel additive-assisted reaction for the synthesis of dihydropyridines using copper salts as catalyst has been described. The (imino)pyridine skeletons were obtained in acceptable yields through a domino reaction involving terminal alkynes, carbodiimides, and acetylenic esters. Control experiments were conducted to explore the reaction path and to prove the mechanism proposed for the reaction.

Synthesis of 2,3,5-Substituted 1H-Pyrroles by a Cp2TiCl2-catalyzed Multicomponent Reaction of Terminal Alkynes with Nitriles and EtAlCl2

A one-pot synthesis of 2,3,5-substituted 1H-pyrroles with yields of 37–77% by the reaction of terminal alkynes with aromatic and heteroaromatic nitriles in the presence of EtAlCl2 and the Cp2TiCl2 catalyst has been developed. Spectral-luminescent properties were studied and intense photoluminescence of 2,3,5-triphenyl-1H-pyrrole, 3-(2-phenylethyl)-2,5-diphenyl-1H-pyrrole, and 2,5-diphenyl-3-(pyridin-2-yl)-1H-pyrrole had been detected.

Copper Nanoparticle Catalyzed Reductive Coupling Reactions of Terminal Alkynes

Copper Nanoparticle Catalyzed Reductive Coupling Reactions of Terminal Alkynes

Copper quinolate: A simple and efficient catalytic complex for coupling reactions

We describe an effective and novel method to prepare N‐aryl imidazoles via the copper quinolate‐catalyzed N‐arylation of aryl halides and imidazoles. A wide range of products were obtained in moderate to excellent yields under the optimal reaction conditions. Applying standard conditions, the model reaction could be performed on a gram scale. This method also presents a new avenue to the “click” reaction of terminal alkynes, benzyl bromide, and sodium azide and to the construction of C–C bonds by homocoupling of phenylboronic acid or phenylacetylene derivatives with the aid of copper quinolate.

Diastereo- and Enantioselective Synthesis of (E)-δ-Boryl-Substituted anti-Homoallylic Alcohols in Two Steps from Terminal Alkynes.

We report the highly diastereo- and enantioselective preparation of (E)-δ-boryl-substituted anti-homoallylic alcohols in two steps from terminal alkynes. This method consists of a cobalt(II)-catalyzed 1,1-diboration reaction of terminal alkynes with B2 pin2 and a palladium(I)-mediated asymmetric allylation reaction of the resulting 1,1-di(boryl)alk-1-enes with aldehydes in the presence of a chiral phosphoric acid. Propyne, which is produced as the byproduct during petroleum refining, could be used as the starting material to construct homoallylic alcohols that are otherwise difficult to synthesize with high stereocontrol.

Diastereo‐ and Enantioselective Synthesis of (E)‐δ‐Boryl‐Substituted anti‐Homoallylic Alcohols in Two Steps from Terminal Alkynes

AbstractWe report the highly diastereo‐ and enantioselective preparation of (E)‐δ‐boryl‐substituted anti‐homoallylic alcohols in two steps from terminal alkynes. This method consists of a cobalt(II)‐catalyzed 1,1‐diboration reaction of terminal alkynes with B2pin2 and a palladium(I)‐mediated asymmetric allylation reaction of the resulting 1,1‐di(boryl)alk‐1‐enes with aldehydes in the presence of a chiral phosphoric acid. Propyne, which is produced as the byproduct during petroleum refining, could be used as the starting material to construct homoallylic alcohols that are otherwise difficult to synthesize with high stereocontrol.

Copper-catalyzed interrupted click reaction: The synthesis of 3-difluoromethyl-substituted 1,2,4-triazinones

A copper-catalyzed interrupted click reaction for the preparation of 3-difluoromethyl-substituted 1,2,4-triazinones is developed. The reaction of terminal alkyne with azide and difluoroacetic anhydride affords the desired products in moderate to good yields. This method provides ready access to 3-difluoromethyl 1,2,4-triazinones, notable synthetic targets, from simple, readily available starting materials. Additionally, the reaction with chlorodifluoroacetic anhydride affords the corresponding 3-chlorodifluoromethyl-substituted 1,2,4-triazinones.

Catalytic Reactions of Terminal Alkynes Using Rhodium(I) Complexes Bearing 8-Quinolinolate Ligands

8-Quinolinolate is a monoanionic, hard, strongly σ-donating ligand that can form strong chelates with various metals. However, studies of the catalytic activities of soft transition metal complexes such as greater than second row, low-valent, late-transition metals having 8-quinolinolate ligands had not been well explored until recently. In recent years, several research groups including our own have studied and developed various reactions of terminal alkynes using rhodium(I) catalysts containing an 8-quinolinolate ligand. In this Perspective, we surveyed the transformations of terminal alkynes using 8-quinolinolato rhodium(I) catalyst such as additions of alcohols, amines, and thiols as well as polymerization, trimerization, dimerization, and alkyne/alkene [2 + 2] cycloaddition. Mechanistic studies based on theoretical calculations of hydroalkoxylation of alkynes and alkyne/alkene [2 + 2] cycloaddition reactions have also been described.

Magnetic copper ferrite catalyzed homo‐ and cross‐coupling reaction of terminal alkynes under ambient atmosphere

The application of non‐toxic and magnetically separable nano‐CuFe2O4 as an efficient catalyst for oxidative homo‐ and cross‐coupling reaction of terminal alkynes is described. A wide range of symmetrical and unsymmetrical 1,3‐diynes have been synthesized in moderate to good yields under ambient atmosphere. The nano CuFe2O4 can be recovered with a magnet and reused at least five consecutive cycles with no appreciable loss of its catalytic activity.