Phenylacetylene Research Articles

THE COPPER-BASED METAL ORGANIC FRAMEWORKS - CUOBA USED AS AN EFFICIENT HETEROGENEOUS CATALYST FOR COUPLING REACTION OF PHENYLACETYELENE AND ETHYL GLYOXALATE

The copper-based metal organic frameworks - CuOBA was synthesized by a solvothermal method. The physicochemical properties and structural characteristics of the CuOBA material were examined by several techniques, including Fourier-transform Infrared (FT-IR), X-ray powder diffraction (PXRD), thermal gravimetric analysis (TGA), Transmission Electron Microscopy (TEM). The CuOBA material was used as an efficient heterogeneous catalyst for the coupling reaction of phenyl acetylene and ethyl glyoxalate in the presence of 1 equivalent morpholine as a base to form 1.2-dicarbonyl-3-ene product. The yield of transformation was more than 90% at 80oC with 9 mol% CuOBA catalyst after 4 hours. The results showed that CuOBA could be recovered and reused seven times without a significant degradation in its catalytic activity.

DFT Studies on the Molecular Structure, Regioisomerism, Ground and Excited state Charge Transfer Properties of Spiro‐heterocycles

AbstractThe electronic structure, stereochemical aspects and charge transfer properties of the spiro compound (5S,8S) spiro‐{6‐phenyl‐1‐aza‐3‐oxa‐7‐thia‐bicyclo[3,3,0]‐octene‐8,3’(2’H)‐indol}‐2’‐one (spiro bicyclo adduct) synthesized using the multi‐component reaction via 1,3‐dipolar cycloaddition of isatin and thioproline with the dipolarophile phenylacetylene have been studied. The two lowest energy regio‐isomers of the spiro heterocycle formed from the stereospecific dipolar reaction have been analysed along with the electron‐withdrawing and releasing substituents using DFT method at the CAM‐B3LYP/6‐311++G(d,p) level of theory. The atomic charges and the stabilization energy due to the intramolecular charge delocalization process calculated using the natural orbitals at the different molecular sites reveal the different donor‐acceptor interactions occurring in the system. The intramolecular electronic transitions (specifically n to π* and π to π*) is found to occur from the localized donor end component to the acceptor end components in the multi‐component system. The hole produced by the ionization of the entities is found to migrate from the thioproline component to the phenyl acetylene part in a time scale of around 4 fs. The electron‐withdrawing and donating substituents on the spirobicyclo adduct have been proven to tune the excited and ground state charge transfer properties uniquely. The results can shed light on how multi‐component reactions can be directed to produce spiro adducts with versatile applications.

Matching Bidentate Ligand Anchoring: an Accurate Control Strategy for Stable Single-Atom/ZIF Nanocatalysts.

Improving metal loading and controlling the coordination environment is nontrivial and challenging for single-atom catalysts (SACs), which have the greatest atomic efficiency and largest number of interface sites. In this study, a matching bidentate ligand (MBL) anchoring strategy was designed for the construction of CuN4 SACs with tunable coordination environment(Cu loading range from 0.4 to15.4 wt%). The obtained Cu SA/ ZIF (0.4 wt%) (ZIF = Zeolitic imidazolate framework with Matching bidentate N-ligands) nanocomposites exhibited superior performance in homo-coupling of phenyl acetylene under light irradiation (TON = 580, selectivity > 99%), which was 22 times higher than that of Cu SA/NC-800 (NC = N-doped porous carbon). Experiments and density functional theory calculations confirmed that the specific Cu five-membered ring formed using the MBL anchoring strategy was the key to the immobilization of isolated Cu atoms. This strategy provides a basis for the construction of M SA/MOF, which has the potential to narrow the gap between experimental and theoretical catalysis, as further confirmed by the successful preparation of Fe SA/ZIF and Ni SA/ZIF. This article is protected by copyright. All rights reserved.

Microwave‐Assisted Tandem Copper‐Catalyzed Three‐Component Reaction for Synthesis of 2‐Iminopyrans

AbstractThe iminopyrans were synthesized by the CuAAC‐MCR approach, the coupling of enaminones, phenyl acetylenes, and sulfonyl, under microwave treatment. The mechanism of the formation of iminopyrans along with amidine has been studied in detail. Experiments to minimize amidine formation were explored, and unfortunately, these experiments were unsuccessful. Molar equivalents of enaminones, phenyl acetylenes, and sulfonyl were optimized to increase the yield of iminopyran. Fluorescent properties of iminopyrans were characterized using Frontier molecular orbital analysis, UV absorption, and emission studies.

Photocatalytic reductive carboxylation of terminal alkynes with CO2 using heterostructured ZIF-7/BiOBr under visible-light illumination

Carboxylation of the organic compounds utilizing CO2 is a challenging task because of the higher thermodynamic stability and chemical inertness of the CO2 molecule. In the present study a straight protocol for the reductive carboxylation of terminal alkynes with CO2 has been developed, providing regioselective synthesis of α, β-unsaturated carboxylic acids using a heterostructured photocatalyst composed of Zn-benzimidazolate framework (ZIF-7) and BiOBr without any additional reducing agent at room temperature and atmospheric pressure conditions. The electron rich derivatives of phenyl acetylene substrates afforded α-acids; whereas, electron deficient substrates provided terminal acids. The DFT calculations indicated the type-II band alignment nature of ZIF-7/BiOBr in which electrons migrated from the ZIF to BiOBr and interacted with CO2 to generate CO2 radical anion at the conduction band of BiOBr.

Palladium Nanoparticles from Desulfovibrio alaskensis G20 Catalyze Biocompatible Sonogashira and Biohydrogenation Cascades.

Transition-metal nanoparticles produced by living bacteria are emerging as novel catalysts for sustainable synthesis. However, the scope of their catalytic activity and their ability to be integrated within metabolic pathways for the bioproduction of non-natural small molecules has been underexplored. Herein we report that Pd nanoparticles synthesized by the sulfate-reducing bacterium Desulfovibrio alaskensis G20 (DaPdNPs) catalyze the Sonogashira coupling of phenyl acetylenes and aryl iodides, and the subsequent one-pot hydrogenation to bibenzyl derivatives using hydrogen gas generated from d-glucose by engineered Escherichia coli DD-2. The formal hydroarylation reaction is biocompatible, occurs in aqueous media at ambient temperature, and affords products in 70-99% overall yield. This is the first reported microbial nanoparticle to catalyze the Sonogashira reaction and the first demonstration that these biogenic catalysts can be interfaced with the products of engineered metabolism for small molecule synthesis.

Synthesis of steroidal dihydropyrazole derivatives using green ZnO NPs and evaluation of their anticancer and antioxidant activity

Zinc oxide nanoparticles (ZnO NPs) were synthesized by a green method using Azadirachta indica leaf extract. The structure of the prepared ZnO (NPs) were characterized by FT-IR, XRD, SEM-EDX and TEM analyses. The biosynthesized ZnO (NPs) were then used as a catalyst for the synthesis of steroidal dihydropyrazole derivatives through a one-pot multicomponent reaction involving phenyl acetylene and hydrazine derivatives. The anticancer activity of newly synthesized compounds were evaluated against three cancer cell lines namely HeLa (human cervical carcinoma), Hep3B (human hepatocellular carcinoma) and MCF7 (human breast adenocarcinoma) by MTT assay. The tested compounds were found to be active against all cancer cell lines and less toxic towards normal peripheral blood mononuclear cells (PBMCs). Antioxidant activity have also been investigated via free radical scavenging ability using DPPH, FRAP and ABTS assay. The tested compounds were found to exhibit moderate to good antioxidant activity which increases with increase in the concentration of steroidal dihydropyrazoles. Among all the tested steroidal dihydropyrazoles, compound 17 is found to be most active.

Reactivity and Stability of a Ring-Expanded N-Heterocyclic Carbene Copper(I) Boryl Imidinate

Frustrated Lewis pairs (FLPs) have evolved from a revolutionary concept to widely applied catalysts. We recently reported the ring-expanded N-heterocyclic carbene supported copper(I) boryliminomethanide, (6-Dipp)CuC(=NtBu)Bpin and noted it reacted with heterocumulenes in a fashion reminiscent of FLPs. We thus set out to explore its reactivity with a range of other substrates known to react with FLPs. This was undertaken by a series of synthetic studies using NMR spectroscopy, mass spectrometry, IR spectroscopy, and single crystal X-ray crystallography. (6-Dipp)CuC(=NtBu)Bpin was investigated for its reactivity towards water, hydrogen, and phenylacetylene. Its solution stability was also explored. Upon heating, (6-Dipp)CuC(=NtBu)Bpin decomposed to (6-Dipp)CuCN, which was characterised by SC-XRD and NMR spectroscopy, and pinBtBu. Although no reaction was observed with hydrogen, (6-Dipp)CuC(=NtBu)Bpin reacted with water to form (6-Dipp)CuC(=N(H)tBu)B(OH)pin, which was structurally characterised. In contrast to its FLP-reminiscent heterolytic cleavage reactivity towards water, (6-Dipp)CuC(=NtBu)Bpin acted as a Brønsted base towards phenyl acetylene generating (6-Dipp)CuCCPh, which was characterised by SC-XRD, IR, and NMR spectroscopy, and HC(=NtBu)Bpin

Mono‐Acetylenes as New Crosslinkers for All‐Carbon Living Charge Carbon Nanotubide Organogels

AbstractNanomaterials, such as single‐walled carbon nanotubes (SWCNTs) and graphenes, can be readily gelled using bi‐ or multi‐functional reagents as crosslinkers. This study reports a new reaction of monofunctional acetylenes with negatively charged SWCNTs (nanotubides), prepared by reduction. Mono‐acetylenes (e. g. phenylacetylene (PAc) and diphenyl acetylene (DiPAc)) are introduced as crosslinkers to form all‐carbon SWCNT organogels at room temperature. The resulting isolated SWCNT aerogels have a density of ∼4.5–5.5 mg cm−3. Raman spectroscopy and thermogravimetric analysis suggest a covalent surface modification (∼1 functional group per 110 (PAc) and 712 (DiPAc) SWCNT carbon atoms). Significantly, the acetylene reaction does not consume all available negative charges. The SWCNT organogel is still reactive after crosslinking and can reduce a stable gold complex, chloro(triphenylphosphine)gold (I), to form AuNPs (∼12–14 nm), suggesting the formation of a living nanotubide organogel intermediate, suitable for a range of secondary reactions. Mono‐acetylenes can crosslink other negatively charged molecular systems, and surface decoration of the aerogels with other metal NPs is anticipated.

Recoverable low fluorine content palladium complex-catalyzed Suzuki-Miyaura and Sonogashira coupling reactions under thermomorphic mode

The reaction of [PdCl2(CH3CN)2] and bis-5,5'-(RfCH2OCH2)-2,2′-bpy (1), where Rf = n-C4F8H, in the presence of dichloromethane (CH2Cl2) resulted in the synthesis of low fluorine content Pd complex, [PdCl2 [5,5′-bis-(RfCH2OCH2)-2,2′-bpy] (2). The Pd-catalyzed Suzuki-Miyaura and Sonogashira coupling reactions of several aryl halides with their respective reagents were selected to demonstrate the feasibility of catalytic activity and recycling usage with 2 as the catalyst by using dibutyl ether (DBE) as the solvent at 140–145 °C under the thermomorphic mode. The Pd complex 2-catalyzed Suzuki-Miyaura reactions of different aryl iodides with phenylboronic acid derivatives have showed good recycling results though its activity was observed to decrease after the fifth cycle. Similarly, 2-catalyzed Sonogashira reactions of several aryl iodides with phenyl acetylene have also displayed good recycling results for a total of up to 8 cycles, with a high yield and TON. The electronic effect studies from substituents in both Suzuki-Miyaura and Sonogashira coupling reactions showed that electron withdrawing groups on the aryl iodide speed up the reaction rate. Furthermore, the catalytic activity of the Pd complex (2) showed a better result with the more reactive aryl iodide compared to the less reactive aryl bromide and chloride. To our knowledge, this is the first example of recoverable low fluorine content Pd-catalyzed Suzuki-Miyaura and Sonogashira reactions under the thermomorphic mode.

Cu (Ι) catalyzed A3 cascade coupling via C‐H functionalization followed by cyclization: Synthesis, in silico, in vitro, and toxicity studies of imidazo[2,1‐b]thiazoles

An influential method for the synthesis of imidazo[2,1‐b]thiazoles via copper (I) catalysis was advanced through a multicomponent coupling of pharmacological scaffolds involving 2‐aminothiazolyl‐coumarin, benzaldehyde, and phenyl acetylene, a concealed variation. The protocol allows the establishment of highly efficient and user‐friendly catalytic system for the A3 cascade coupling; also, an environmentally benign, economical, and readily obtainable CuSO4/sodium ascorbate is portrayed. A sequence of 15 novel imidazo[2,1‐b]thiazoles (7j–x) were synthesized and evaluated for their in vitro antimicrobial activity, in silico studies, and oral toxicity studies. The in vitro antifungal and antibacterial screening of synthesized compounds manifested favorable activity and disclosed that all these previously unknown compounds showed significant activity. Amid them, compound 7u portrayed the most effective inhibitory activity.

Highly Selective Semihydrogenation via a Wettability-Regulated Mass Transfer Process

Desired catalytic performance can be achieved by regulating the wettability of heterogeneous catalysts. Herein, by loading palladium nanoparticles within heterostructural gel supports, we achieved the wettability-controlled selective hydrogenation of phenylacetylene (PT) into styrene (ST) or ethylbenzene (ET) in aqueous media. During catalysis, the selectivity toward ST improved significantly as the catalyst hydrophilicity increased. Additionally, catalyst’s wettability had a negligible influence on its efficiency in the hydrogenation of PT. Mechanistic studies revealed that the catalyst’s wettability has less effect on its affinity for PT but markedly influences its affinity for ST. Hydrophobic catalysts favorably adsorbed semi-hydrogenated products (ST) and fully hydrogenated them to the corresponding ET. Contrastingly, hydrogenation of PT over hydrophilic catalysts remained in a semi-hydrogenated state owing to the quick desorption of ST from the catalyst surface, resulting from weak ST-catalyst interactions. We believe that the proposed strategy will be applicable in a wide range of heterogeneous catalysis reactions.

Montmorillonite KSF mediated Favorskii reaction-based eco-friendly fabrication of some 1,3-diarylpropenones using phenyl acetylene and aromatic aldehydes

Montmorillonite KSF mediated Favorskii reaction-based eco-friendly fabrication of some 1,3-diarylpropenones using phenyl acetylene and aromatic aldehydes

Synthesis and Reactivity of Triangular Heterometallic Complexes Containing Zn-Zn Bond.

This work provides a facile access to a series of triangular [Zn2M] (M = group 10 and 11 metals) clusters. Treatment of Zn-Zn-bonded compounds [LZn-ZnL] (L = CH3C(2,6-iPr2C6H3N)CHC(CH3)(NCH2CH2PR2); R = Ph, iPr) with zero-valent transition-metal reagents selectively afforded the corresponding triangular clusters [Zn2M], where M = Ni(0), Pd(0), and Pt(0). Notably, the isoelectronic triangular clusters [Zn2M]+, where M = Ag(I) and Cu(I), could also be obtained by reactions of [LZn-ZnL] with AgOTf and CuOTf, respectively. The [Zn2Ag]+ complex containing elusive Zn-Ag bonds was investigated by density functional theory analysis, showing a 3c-2e bonding feature in the metallic ring. The electrochemical behaviors of [Zn2M] complexes were examined and revealed the donation of electron density from the Zn-Zn σ-bond to the metal centers. Reaction of the [Zn2Ni] complex with isocyanide gave heterometallic species by coordination of isocyanide to the nickel center, keeping the trimetallic ring core structure intact. In contrast, the Zn-Zn bond was rapidly cleaved upon treatment of the [Zn2Ni] complex with dihydrogen or phenyl acetylene, generating the hydride- or acetylide-bridged heterotrimetallic complex.

Ultrasonic-Assisted Sulfonated Biochar Derived from Rice Husk for Catalytic Hydration of Phenylacetylene

The Rice husk (RH) was carbonized and post-synthetically ultrasonicated with sulfuric acid to yield the solid acid catalyst (RBs). The presence of acidic groups was confirmed by X-ray photoelectron spectroscopy (XPS), and X-ray energy dispersion spectroscopy (EDS). In the present work, the prepared catalyst was tested against hydration of phenylacetylene (PA) in aqueous media, allowing the facile separation of catalyst for recycling. The biochar-based acid catalyst assisted in the lowering of activation energy needed for the synthesis of the Markovnikov addition product.

Efficient multicomponent synthesis of propargylamines catalyzed by Cu(I) complexes encompassing hydrazone ligands under solvent-free condition

A series of copper(I) complexes with hydrazone ligands of the type [Cu(PPh3)2(L)] (1–3) were synthesized by the reacting [Cu(PPh3)2(CH3COO)] with hydrazone ligands (L1-3) [L1 = 2-(oxoacenaphthylen- 1, 2-ylidene)benzohydrazone (BHy-BIAN), L2 = 2-(oxoacenaphthylen-1, 2-ylidene)thiophene-2-carbohydrazone (FHy-BIAN), and L3 = 2-(oxoacenaphthylen-1,2-ylidene)isonicotinohydrazone (NHy-BIAN). The formation of synthesized complexes were characterized by micro analyses and spectral (IR, UV–Vis, 1H &13C NMR, ESI-mass and single crystal XRD) studies. Specifically, the solid state structural study demonstrates distorted tetrahedral geometry of donor atoms around copper atom. The synthesized copper complexes were utilized as reusable homogeneous catalysts in A3 coupling reactions involving aldehydes, amines and phenyl acetylene for the synthesis of propargylamines under solvent-free conditions. Particularly, complex 2 has been found to be highly efficient in the synthesis of propargylamines. Many novel compounds have been synthesized based on A3 coupling reaction and the formation of new compounds was confirmed by TLC as well as 1H and 13C NMR spectroscopy.

Highly efficient, iodide catalysed propargylamines synthesis via A3 coupling reaction

A new and facile methodology was developed for the synthesis of a wide variety of synthetically important propargylamines via the A3 coupling reaction of aryl aldehydes, phenyl acetylenes, and amines. The reaction was catalyzed by tetra-butyl ammonium iodide (TBAI) in solvent acetonitrile utilizing a multi-component approach. The reaction is unique in the way that it operates smoothly in the air at optimum temperature in shorter reaction duration without any metal catalyst and is high yielding.

Multi-functional palladium-ruthenium nanocomposites: an approach towards semi-hydrogenation catalysis and hydrogen sorption.

Development of heterogeneous metal catalysts with superior activity and high selectivity towards the semi-hydrogenation of alkynes is of significant industrial importance. Bimetallic Pd-Ru nanocomposites were synthesized over the entire composition range using a capping-agent assisted solution-based approach. The as-prepared nanocomposites demonstrated excellent catalytic activity towards the hydrogenation of a wide range of olefinic substrates and exceptional selectivity towards styrene in a phenylacetylene semi-hydrogenation reaction under mild conditions. In addition, hydrogen sorption studies were performed on the as-prepared bimetallic Pd-Ru nanomaterials, where an increase in the incorporation of Ru atoms into the bimetallic structure resulted in a decrease in the hydrogen storage capacity of the resulting material. Comprehensive structural characterization and insights obtained from the hydrogen sorption studies revealed that the presence of weakly bound hydrogen atoms in the hydride phase of the bimetallic species contributes to its excellent selectivity in hydrogenation reactions.

Engineering the HOMO–LUMO gap of indeno[1,2-b]fluorene

The insertion of phenyl acetylenes at the reactive positions of indeno[1,2-b]fluorene leads to tune its optoelectronic and magnetic properties. Furthermore, its single-molecule conductance has been investigated for the first time.

Unraveling high alkene selectivity at full conversion in alkyne hydrogenation over Ni under continuous flow conditions

Carbon dissolution in Ni lattices decreased the interaction of alkenes with the catalyst surface and gave an elusive combination of full phenyl acetylene conversion and high styrene selectivity (92 ± 1%) under continuous flow conditions.