Alkynes In Water Research Articles

Ru-Catalyzed Redox-Neutral Coupling of N-Chlorobenzamides with Unsymmetrical Alkynes in Water.

In water, Ru-catalyzed annulation of N-chlorobenzamides with unsymmetrical internal alkynes bearing aryl, hydroxy, ester, and sulfonyl functionalities has been accomplished to afford isoquinolone scaffolds under external oxidant-free conditions at room temperature. Use of water as reaction medium, redox-neutral conditions, regioselectivity, and substrate scope are important practical features.

Mesoporous Palladium Catalyst for Efficient Electrochemical Semi‐Hydrogenation of Alkynes

AbstractDeveloping robust electrocatalysts for efficient semi‐hydrogenation of alkynes to markedly important alkenes is highly desirable in both research and industry areas. In this work, it is reported that robust palladium mesoporous nanospheres (Pd MSs) with electron‐rich active sites perform perfectly as cathode electrocatalyst for electrochemical semi‐hydrogenation of alkynes in water. In comparison to its counterparts, Pd MSs hold remarkable conversion (97%), superior selectivity (98%), good operation stability in selective semi‐hydrogenation of p‐aminophenylene. High performance is assigned to electron‐rich Pd sites within mesopores that not only favor the formation of active H* but also accelerate the desorption of p‐aminostyrene. Meanwhile, Pd MSs are also highly efficient in selective semi‐hydrogenation of various terminal alkynes with different substituents. It is thus expected that robust Pd MSs can be demonstrated as an alternative catalyst design paradigm for other electrochemical hydrogenation reactions.

Synthesis of Sulfonimidamide‐Based 1,2‐Benzothiazines by [4+2] Oxidative Annulation of Sulfonimidamides and Alkynes in Water under Visible Light

AbstractHerein, we disclose a visible‐light‐induced rhodium‐catalyzed oxidative C−H/N−H bond activation of sulfonimidamides (SIAs) and subsequent [4+2] annulation with an alkyne in water to yield SIA‐based 1,2‐benzothiazines in good to high yields in short reaction times. Further, the C=C bond of the benzothiazine can be cleaved under environmentally friendly conditions (oxygen atmosphere and blue LEDs) to deliver o‐acyl‐N‐acyl SIAs. Interestingly, o‐acyl‐N‐acyl SIAs can also be synthesized directly from SIAs in very good yields without isolating the benzothiazine. The selective and efficient reduction of the benzothiazine C=C bond in the presence of InCl3/R3SiH led to the formation of a hitherto unknown SIA‐based dihydro‐1,2‐benzothiazine in quantitative yield.

Stable homogeneous silver(I) catalysts for the highly efficient cycloaddition of azides onto terminal alkynes in water.

To develop stable and efficient silver(I) catalysts and evaluate the role of sulfur and phosphorus donor ligands in the catalytic cycloaddition of selected organic azides and alkynes (AAC), a series of mononuclear Ag(I) and heteronuclear Ag(I)-Fe(II) complexes were synthesized. The synthesis utilized phosphine and sulfur donors from the dialkyldithiophosphate and borate families, specifically Na[S2H2B(mt)2]. These complexes are designated as [(dppf)AgSP(S)(OiPr)2] (1), [S2H2B(mt)2Ag(μ-dppf)AgS2H2B(mt)2] (2), [(dppf)Ag(μ-dppf)Ag(dppf)] (3), and [(dppe)AgS2H2B(mt)2] (5). The complexes 1-5 were characterized using a combination of 1H, 13C{1H}, and 31P{1H} NMR spectroscopy, as well as IR spectroscopy techniques. In two instances, single-crystal X-ray diffraction analysis was also employed. Complex 3 exhibited high catalytic activity and regioselectivity in the cycloaddition reaction conducted in water at 40 °C.

Iridium-catalyzed reductive hydroamination of terminal alkynes in water

Herein, we report an efficient one-pot iridium-catalyzed reductive hydroamination of terminal alkynes with amines. A variety of primary amines and secondary amines are amenable to this catalytic system, leading to the complicated aliphatic amines in excellent yields. More broadly, this straightforward and convenient transformation do not just employ inexpensive and easy to handle HCO2H as reducing agent, but also employs H2O as reaction media, which makes this strategy be in accordance with green and sustainable chemistry principles.

Highly selective catalyst- and additive-free iodosulfonylation of cyclopropenes in water

A highly operationally convenient and environmentally benign approach of the iodosulfonylation of cyclopropenes, styrenes, and alkynes in water has been reported.

A new Cu3Al-layered double hydroxide heterogeneous catalyst for azide-alkyne [3 + 2] cycloaddition reaction in water

A new Cu3Al-layered double hydroxide (LDH) compound that contains Cu2+ and Al3+ in a 3:1 copper to aluminum molar ratio was synthesized by a coprecipitation method at constant pH and characterized by various methods. Cu3Al-LDH was efficiently used as a catalyst for the regioselective click of 1,4-disubstituted-1,2,3-triazoles by [3 + 2] cycloaddition of several azides and alkynes in water under ambient conditions. The investigated heterogeneous Cu3Al-LDH catalyst was used in lower copper catalyst loading in absence of any additive reducing agent, showing good stability in terms of copper species leaching as well as reusability associated to the loss of the layered structure to some extent during the process of filtration-dehydration.

Synthesis of Quinine-Triazole Derivatives (QNTDs) with Antifungal Potency

Background: Reduced efficacy of the available antifungal drugs is the major public health concern of the population all over the world. Despite significant advances in the treatment of these life-threatening infections, severe toxicity and increasing median effective dose have lim-ited the efficacy of frontline therapy applicable against them. Objective: The quintessential occurrence of systemic toxicity handicaps the clinical utility of cur-rently available antifungal drugs. 1,2,3-Triazoles in the same context are relatively less toxic. Con-sequently, conjugation of quinine with the triazole moiety for enhanced efficacy and reduced tox-icity have been excessively envisaged and reported in the context of a range of activities ranging from inflammation to cancer, however lack of toxicity profile sabotages the translation of the la-boratory prototype into successful clinical practice. Method: We herein report the synthesis and characterization of a series of quinine triazole hybrids via o-mesylation followed by azide displacement, then reacting it with aliphatic and aromatic al-kynes in water: t-butanol mixture. The reaction was carried in the presence of copper sulphate and sodium ascorbate. Product 6a-s was screened for in-vitro antifungal activity. The in-vitro antifungal potential of synthesized compounds was estimated against prominent fungal strains (Candida albi-cans, Aspergillus niger and, Aspergillus clavatus). Results: The results showed that some of the synthesized compounds exhibited marked activity. Compounds 6a, 6b, 6c, 6d, 6g, and 6q showed significant antifungal activity at micromolar con-centration. The studies revealed that some of the compounds exhibited activities more than that of reference drugs. The compound containing thiazole ring 6c is the most potent compound of the series. Conclusion: Compound 6c was found to be the most vigorous against C. albicans, A. niger, A. clavatus with MIC values of 119.4, 112.7, and 121.3 μM/mL, respectively. Our SAR study re-vealed that the introduction of the 1,2,3-triazole ring in the structure of quinine modulated its po-tency for treating fungal infection.

Palladium-catalyzed hydroboration reaction of unactivated alkynes with bis (pinacolato) diboron in water.

A highly efficient and mild palladium-catalyzed hydroboration of unactivated internal alkynes in water is described. Both aryl- and alkyl-substituted alkynes proceeded smoothly within the reaction time to afford the desired vinylboronates in moderate to high yields. Bis (pinacolato) diboron was used to afford α- and β-hydroborated products in the presence of HOAc. These reactions showed high reactivities and tolerance, thus providing a promising method for the synthesis of alkenyl boron compounds.

Functionalized-1,3,4-oxadiazole ligands for the ruthenium-catalyzed Lemieux-Johnson type oxidation of olefins and alkynes in water

Three arene-ruthenium(II) complexes bearing alkyloxy(5-phenyl-1,3,4-oxadiazol-2-ylamino)(4-trifluoromethylphenyl)methyl ligands were quantitatively obtained through the reaction of (E)-1-(4-trifluoromethylphenyl)-N-(5-phenyl-1,3,4-oxadiazol-2-yl)-methanimine with the ruthenium precursor [RuCl2(η6-p-cymene)]2 in a mixture of the corresponding alcohol and CH2Cl2 at 50 °C. The obtained complexes were fully characterized by elemental analysis, infrared, NMR and mass spectrometry. Solid-state structures confirmed the coordination of the 1,3,4-oxadiazole moiety to the ruthenium center via their electronically enriched nitrogen atom at position 3 in the aromatic ring. These complexes were evaluated as precatalysts in the Lemieux-Johnson type oxidative cleavage of olefins and alkynes in water at room temperature with NaIO4 as oxidizing agent. Good to full conversions of olefins into the corresponding aldehydes were measured, but low catalytic activity was observed in the case of alkynes. In order to get more insight into the mechanism, three analogue arene-ruthenium complexes were synthesized and tested in the oxidative cleavage of styrene. The latter tests clearly demonstrated the importance of the hemilabile alkyloxy groups, which may form more stable (N,O)-chelate intermediates and increase the efficiency of the cis-dioxo-ruthenium(VI) catalyst.

Cover Feature: In water Markovnikov hydration and one‐pot reductive hydroamination of terminal alkynes under Ruthenium nanoparticle catalysis (Eur. J. Inorg. Chem. 11‐12/2020)

The Cover Feature shows a procedure that enables the reductive hydro-amination of aromatic alkynes in water as the only solvent. The reagents and the Ru catalyst are assembled within nanomicelles that release the final product into the water. The product is recovered from the water surface. The background shoreline image reminds us of the eternal relationship between the sea and mankind, who stays on dry land and obtains resources out of the sea. Nanomicellar reactors do the same, generating products in water and releasing them out of the water after the man on the beach has had fun playing with nanomicellar chemistry. More information can be found in the Communication by M. Taddei et al.

Preparation of an efficient catalyst through injection of CuI on modified poly (styrene‐co‐maleic anhydride) and theoretical investigation of the structural and electronic properties of catalyst

A novel polymer supported [poly (styrene‐co‐maleic imide) (SMI)]Cu(I) nano‐particles was prepared via in situ reaction of 4‐amino‐5‐methyl‐4H‐1,2,4‐triazole‐3‐thione with [poly (styrene‐co‐maleic anhydride)] (SMA) along with immobilization of CuI. These nano‐particles were fully characterized by using scanning electron microscopy (SEM), energy dispersive spectroscopy analysis, Xray (EDAX), inductively coupled plasma (ICP) analysis, 1H NMR and FT‐IR techniques. Moreover, the structural and electronic features of metal–ligand interactions in the complex model of polymer‐supported copper nanocatalyst were assessed using density functional theory calculations. The catalytic activity of these supported Cu(I) nonoparticles was examined in one of the classiest name reaction so–called “click reaction” which is coined K. B Sharpless for the regioselective synthesis of 1,2,3‐triazole derivatives using a multicomponent reaction (MCR) involving benzyl halides, sodium azide and terminal alkynes in water as a green solvent. This heterogeneous catalyst showed excellent catalytic activity and was separated by simple filtration and was used at least in five consecutive runs without a significant decrease in its activity.

Ruthenium(II)‐Catalyzed C−H Bond [3+2] Annulation of N‐Nitrosoanilines with Alkynes in Water

AbstractAn efficient RuII‐catalyzed C−H bond redox‐neutral annulation of N‐nitrosoanilines with alkynes by employing water as the solvent has been developed. This transformation provides an easy and robust protocol for the synthesis of indoles with a broad range of functional group tolerance and excellent regioselectivity.

Gold(I) Complexes with Ferrocenylphosphino Sulfonate Ligands: Synthesis and Application in the Catalytic Addition of Carboxylic Acids to Internal Alkynes in Water

The synthesis and characterization of novel gold(I) complexes containing hydrophilic ferrocenylphosphino sulfonate ligands, i.e., compounds [AuCl{(η5-C5H3PR2(SO3iPr))Fe(η5-C5H5)}] (R = Ph (2a), p-Tol (2b), Cy (2c)), are presented, including a single-crystal X-ray diffraction study on 2a. Complexes 2a–c were checked as catalysts for the intermolecular addition of carboxylic acids to nonactivated internal alkynes using water as a green reaction medium. The best results in terms of activity were obtained with 2a in combination with AgOAc, which was able to promote the selective anti addition of a variety of aromatic, aliphatic, and α,β-unsaturated carboxylic acids to both symmetrical and unsymmetrical internal alkynes at 60 °C, employing metal loadings of only 2 mol %.

SO3Cu‐Carbon: A Novel Heterogeneous Catalyst for the Synthesis of β‐Hydroxy 1,2,3‐Triazoles by One Pot Cycloaddition Reaction

AbstractA novel heterogeneous carbon‐based sulfonated copper (SO3Cu‐carbon) catalyst was developed for the first time and investigated its catalytic activity for the regioselective synthesis of β‐hydroxy 1,2,3‐triazoles by azide–alkyne cycloaddition in aqueous medium. The SO3Cu‐carbon catalyst was prepared by the modification of the glycerol‐based SO3H‐carbon catalyst on treatment with 10% aqueous CuCl2 solution under controlled conditions. Based on its physico‐chemical characteristics the structure of the catalyst is proposed as a polycyclic aromatic carbon attached with ‐SO3Cu, ‐COOCu and –OCu functionalities. The catalytic activity of the SO3Cu‐carbon catalyst was demonstrated for the one pot ‘click’ reaction of epoxide, sodium azide and terminal alkyne in water at 60 °C for the synthesis of β‐hydroxy 1,2,3‐triazoles in excellent yields (89‐94%) without any additives. The formation of the product proceeds in one pot through a mechanism that involves in situ generation of organic azide intermediate followed by rapid ring closure with alkynes. The catalyst was easily recovered by simple filtration and reused for 5 cycles without any leaching and deactivation thus exhibiting its excellent stability and reusability. Moreover, the cascade reaction was best performed in water at moderate temperature, rendering all the processes truly green.

Hyperbranched polyethylenimine-supported copper(II) ions as a macroliganted homogenous catalyst for strict click reactions of azides and alkynes in water

Loading hyperbranched polyethylenimine (PEI) with copper(II) ions leads to the formation of a new water-soluble metallodendritic polymer Cu(II)-PEI that has been found to effectively catalyze the clickable azide-alkyne [3 + 2] cycloaddition reactions in water under ambient conditions, in the lack of any external reducing agent. A positive dendritic effect on the catalyst activity was observed in the click of 1,2,3-triazole by lowering the reduction potential of copper(II) into the in-situ generation of the catalytically active species copper(I). The reaction proceeds straightforwardly to afford the corresponding 1,4-disubstituted-1,2,3-triazole derivatives in a regioselective manner. The precatalystCu(II)-PEI has been easily recovered and reused for up to ten-sequential applications with a decrease in its catalytic activity.

Metallomicelle catalyzed aerobic tandem desilylation/Glaser reaction in water

The copper complexes of PEG-grafted nitrogen ligands serve as metallomicellar nanoreactors for the aerobic tandem desilylation/Glaser coupling of TMS-protected alkynes in water.

High-silica Hβ zeolites for catalytic hydration of hydrophobic epoxides and alkynes in water

We investigated the hydration of hydrophobic epoxides and alkynes in water using 24 types of heterogeneous and homogeneous catalysts and found that Hbeta (Hβ) zeolite with a relatively high Si/Al ratio (Si/Al = 75), Hβ-75, is an effective catalyst. Hβ-75 showed wide substrate scope, good reusability, and applicability in gram-scale synthesis for both types of reactions. The effects of hydrophobicity, acidity, and the size of zeolite pores were also comprehensively studied through the hydration of hydrophilic and hydrophobic epoxides and alkynes with different molecular sizes using two types of zeolite (Hβ and HZSM5). The high yields obtained using the Hβ-75 catalyst in the hydration of hydrophobic epoxides and alkynes are attributed to the hydrophobic interaction between zeolite pores with the substrates, as well as the relatively large pore size.

Z-Selective Addition of Diaryl Phosphine Oxides to Alkynes via Photoredox Catalysis

Radical addition to alkynes is known to predominantly yield thermodynamically more stable E-alkenes. Control of stereoselectivity in these reactions, and the isolation of the higher-energy Z-alkenes, remain an important challenge in chemical synthesis. Herein, direct synthesis of Z-alkenylphosphine oxides via visible-light-induced radical addition to alkynes in water is reported. This protocol was effective with various terminal and internal alkynes, affording products with high Z-stereoselectivity. Moreover, this transformation was demonstrated on gram scale. Mechanistic studies support the following conclusions: (1) the reaction proceeds via free-radical addition; (2) the choice of K2CO3 as aqueous base is crucial to the transformation; and (3) π–π stacking interaction greatly improves Z-selectivity.

SBA-15-Supported Copper (II) Complex: An Efficient Heterogeneous Catalyst for Azide-Alkyne Cycloaddition in Water

he reaction of the functionalized mesoporous SBA-15 in absolute ethanol with copper(II) acetate afforded a novel CuII-Schiff base/SBA-15 catalyst. The compound CuII-Schiff base/SBA-15 was characterized by IR spectroscopy, small-angle X-ray diffraction (SAX), energy dispersive X-ray Analysis (EDXS), X-ray absorption near edge structure (XANES), scanning electron microscope (SEM), transmission electron microscope (TEM) and N2 adsorption/desorption studies. Further, we tested the catalytic activity of this well-defined material in three-component copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions to obtain 1,4-disubstituted-1,2,3-triazoles in good to excellent yields from an organic halide, sodium azide and alkyne in water as a green solvent. More importantly, the catalyst can be recovered and reused efficiently up to five consecutive cycles with negligible loss of catalytic activity.