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Efficient hydrogenation of organic compounds employing low‐cost and easy‐to‐synthesize catalysts is highly desirable as the corresponding hydrogenated products have significant importance in pharmaceutical and fine‐chemical industries. Herein, a cobalt(II) complex supported by α‐diimine ligand has been easily prepared by treatment of anhydrous CoCl2 with diimine, which can catalyze the hydrogenation of unsaturated bond with ammonia borane as the hydrogen source. A variety of ketones and aldimines bearing diverse functional groups can be reduced to corresponding alcohols and amines in moderate to excellent yields at ambient conditions. It is noteworthy that several readily reducible functional groups such as nitro and cyano are tolerated under the standard reaction conditions. Furthermore, the gram‐scale reaction has been successfully carried out and the procedure could be handled easily, which both make this methodology general and practical. [ABSTRACT FROM AUTHOR]

Various nucleophiles(6-nitroindole, 6-chloroindole, phenol, anisole, and furan) underwent rapid alkylation with propargyl alcohols in the presence of 5 mol % gallium(III) triflate under mild conditions to produce the corresponding products. The reactions can be performed in an undried solvent under air atmosphere in short reaction times and provide good yields. In most cases, the reactions completed within 10 min. [ABSTRACT FROM AUTHOR]

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The synthesis of complex cyclic compounds is extremely challenging for organic chemists. Many transition-metal-salt-mediated cyclizations are reported in literature. Hg(II) salts have been successfully employed in cyclizations to form complex heterocyclic and carbocyclic structures that are impossible to synthesize with other transition metal salts. In this review, we have summarized cyclization reactions that are performed with Hg(II) salts. These salts are also successfully applied in stoichiometric or catalytic amounts to form complex cyclic structures and natural products.

Heterocycles, primarily the nitrogen-containing six-membered triazines, pyrimidines, and pyridines are used in synthesizing the active pharmaceutical synthons and natural products. Catalysis, particularly transition metal catalysis, can also be used to obtain regioselective, stereoselective, and chemoselective transformations. This review work deals with the recent advances made in metal-mediated/catalyzed synthesis of triazine derivatives and therefore will assist chemists in comprehending the issues associated with the present methods as well as future prospects, in terms of substrate and catalyst respectively. This article is of interest to a large area of organic chemists working in the field of heterocyclic productions in academia and industrial R&D sectors. Noteworthy, this assessment will serve as a guiding light to consider: (i) the importance of several transition metals employed in the method development domain and (ii) in the R&D sector for further necessary modifications. [ABSTRACT FROM AUTHOR]

A vital transition metal Cu(II) ion catalyzed reaction was encrypted in the synthesis of new coumarin tethered triazoles 6(a-i) using the substituted azidobenzenes and substituted 3-acetyl-2H-chromen-2-ones in the presence of oxidative potassium persulfate, and DMF as a solvent and C5-H source. The structure proofs of the new compounds were provided by the spectral analysis. The in vitro antimicrobial activities of the target compounds indicate that compounds 6c and 6g of the series have potent inhibition against the tested bacteria and fungi species. Among the synthesized series compound 6g was found potent for α-amylase inhibition activity. Synopsis. Dimethylformamide was used as a solvent and C5-H source reagent in the synthesis of triazole rings. The reaction of substituted azides, 2(a-e) and substituted 3-acetyl-2-oxo-2H-chromenes, 5(a-b) in the presence of a catalytic amount of Cu(NO3)2 and an oxidant K2S2O8 was carried out under reflux conditions using an oil bath for 36-48 h. From the reaction mixture, the target compounds 6(a-i) were extracted with ethyl acetate. The synthesized coumarin-triazole hybrids, 6(a-i) were spectroscopically characterized and evaluated for antimicrobial and α-amylase inhibitory activities. [ABSTRACT FROM AUTHOR]

[Display omitted] Ga(OTf) 3 efficiently catalyses the nucleophilic substitution of the hydroxyl group of propargyl alcohols with enoxysilanes to aid in C C bond formation. The reactions can be performed in an undried solvent under air to obtain the desired products quickly in good yields. Other nucleophiles, such as indole, phenol, and furan are also suitable for this transformation. The use of inexpensive and readily available catalysts makes this method simple, convenient, and practical. [ABSTRACT FROM AUTHOR]

• A remarkable increase in the rate of the oxidation reaction. • SDS and mixed micelles in conjunction with the Bpy demonstrate the highest oxidation rate. • In-depth insights into the mechanistic path of mixed micelle catalyzed reactions are presented. • The utilization of micelles and promoters aligns with the principles of green chemistry. • Mixed micelles hold promise for broader applications in various industrial processes. Oxidation of 1-butanol at 30 °C was carried out using chromic acid in an aqueous medium, employing pseudo 1st order reaction conditions. The resultant 1-butanal was isolated through fractional distillation. Surfactant micelles, acting as tiny templates or nano-reactors, play a vital role in generating nano-structured materials with desired attributes. These micelles have shown promise as effective catalysts, including mixed anionic-nonionic micelles like SDS-TX 100. In the pursuit of enhancing the rate of oxidation, micelle catalysts were tested in conjunction with various promoters. Astonishingly, these combinations displayed an impressive rate acceleration. To validate the products and interactions, comprehensive analyses were conducted using techniques such as IR, NMR, and UV. The formation of mixed micelles was also established through DLS analysis. Interestingly, among the catalytic paths, mixed micelles combined with 2, 2́-Bipyridine (Bpy) promoter exhibited the highest oxidation rate, overshadowing other combinations. Further insight was gained by observing the rate constants: k obs (SDS) > k obs (TX 100) and k obs (Phen) > k obs (Bpy) > k obs (PA) for promoted reactions in single micelle catalysis. For SDS micelles and mixed micelles, the order was k obs (Bpy) > k obs (Phen) > k obs (PA), whereas in TX 100 micelles, it was k obs (Phen) > k obs (Bpy) > k obs (PA). [ABSTRACT FROM AUTHOR]

The methylene group of various substituted 2- and 4-benzylpyridines, benzyldiazines and benzyl(iso)quinolines was successfully oxidized to the corresponding benzylic ketones using a copper or iron catalyst and molecular oxygen as the stoichiometric oxidant. Application of the protocol in API synthesis is exemplified by the alternative synthesis of a precursor to the antimalarial drug Mefloquine. The oxidation method can also be used to prepare metabolites of APIs which is illustrated for the natural product papaverine. ICP–MS analysis of the purified reaction products revealed that the base metal impurity was well below the regulatory limit.

• Silver is dissolved with an improved nitrite-copper system. • Massive consumption of cupric ions by parasite reactions is inhibited. • A decrease in pH significantly favors the silver dissolution kinetics. • Metallic silver of 99.95% of purity can be obtained. • A semi-empiric kinetic model for silver dissolution is developed. • Diffusion of fluid reagents through a porous layer controls the process kinetics. This research presents a systematic-kinetic analysis of silver leaching from pure metallic silver using the NO 2 -Cu2+ novel system, with the aim to maximize the silver recovery and decrease the massive consumption of reagents. The effect of pH, nitrite ions concentration, cupric ions concentration, temperature and stirring rate on silver leaching kinetics and recovery was evaluated. The thermodynamic and leaching results showed that a decrease of pH from 5.4 to 4.5 increases remarkably the silver leaching kinetics, while the parasite precipitation of copper hydroxysulfate species is inhibited. The silver leaching kinetics is also favored when nitrite and copper concentrations are increased up to 1.5 and 0.2 M, respectively. The fundamental kinetic analysis revealed that silver leaching mechanism from its metallic form with this system was incomplete and follows the next kinetic model: t = [ 10-0.52pH [NO 2 –]1.2 [Cu2+]0.522.63 × 109e-56,900/RT][ 1–3(1-x)2/3 + 2(1-x)], where the diffusion of fluid species through a non-conventional ash layer is the rate determining step of the leaching process. Finally, the dissolved silver can be easily recovered in its metallic form (high purity > 99%) using a simple cementation step, which permits the recycling of the leaching solution. [ABSTRACT FROM AUTHOR]

A bio-inspired approach for efficient conversion of cellulose to formic acid ( FA) was developed in an aqueous alkaline medium. Metalloporphyrins mimicking cytochrome P450 exhibit efficiently and selectively catalytic performance in catalytic conversion of cellulose. High yield of FA about 63.7% was obtained by using sulfonated iron( III) porphyrin as the catalyst and O2 as the oxidant. Iron( III)-peroxo species, TSPPFeIIIOO−, was involved to cleave the C-C bonds of gluconic acid to FA in this catalytic system. This approach used relatively high concentration of cellulose and ppm concentration of catalyst. This work may provide a bio-inspired route to efficient conversion of cellulose to FA. [ABSTRACT FROM AUTHOR]

A general atom-economical approach for the synthesis of α-halomethyl ketones is demonstrated through Ce(SO4)2/acid co-catalyzed hydration of a wide range of haloalkynes. The reactions are conducted under convenient conditions and provide products with excellent regioselectivity in good to excellent yields, with broad substrate scope. This protocol is an alternative to conventional α-halogenation of ketones. [ABSTRACT FROM AUTHOR]

An inexpensive 1 mol % FeCl 3 ·6H 2 O reagent has been developed for the synthesis of 1,3-disubstituted 1 H -pyrano[4,3- b ]quinolines from o -arylethnylquinonylmethanol via 6 -endo -dig cyclization of alcoholic –OH onto alkynes in good to excellent yields. The reaction conditions were successfully exploited on primary and tertiary alcohol analogs. The reagent was further generalized with the aromatic alcohol analogs providing the synthesis of isochromenes in good yields. The enhancement in the reaction rates and yields from primary to secondary to tertiary alcohols could be attributed to inductive effect of alkyl groups which enhanced the nucleophilicity of hydroxyl group and accelerated the cyclization mode. [ABSTRACT FROM AUTHOR]

Various benzofuran bromides were dehalogenated using the palladium catalyst and phosphine ligands in the present of 5 equiv water. This set up a new and efficient protocol for the palladium-catalyzed dehalogenation of benzofuran bromides, which could tolerate the presence of water and have selective debromination. [ABSTRACT FROM AUTHOR]

I2-catalyzed base-free reactions of 3-homoallylquinoline-2-thiones have been described for the synthesis of tetracyclic quinolines, tetrahydrofuro [2',4':4,6]thiopyrano[2,3-b]quinolines in excellent yields. Similarly, I2-catalyzed reactions could proceed to tricyclic quinolines from hydroxyl group protected 3-homoallylquinoline-2-thiones. However, deprotection of group in tricyclic quinoline with HI again transformed into tetracyclic quinoline. The sulfonium salt intermediate has been proposed to explain these reactions. [ABSTRACT FROM AUTHOR]

Catalyst gas phase ammoxidation of 2,3, and 4- picolines in a fixed bed reactor is described the catalyst applied composed of Vanadium (V) and tin (Sn) Oxides supported on Al2O3 as described in recent papers (1), (2). The effect of NH3, O2, contact time and temperature of the picoline mole ratios on the yield and conversion of the products was studied. The conversation and yield are in the rate of 2-picoline> 4-picoline > 3-picoline. The applied catalyst was active even after 150 hours of reaction. The highest yield obtained of nicotinic acid was 90%, 88%, 87% 2-picoline, 4-picoline and 3-picoline respectively.

Abstract: Glycosides and thioglycosides based on monosaccharides in reaction with benzaldehyde dimethylacetal or p-methoxybenzaldehyde dimethyl acetal undergo FeCl3-catalyzed (20mol%) regioselective 4,6-O-arylidenation producing the corresponding acetals in high yields. FeCl3 also mediates acetalation of glycosides and thioglycosides of cellobiose, maltose, and lactose affording the corresponding 4′,6′-O-benzylidene acetals, which were isolated after their acetylation in situ with acetic anhydride and pyridine. The combined yields (two steps) of these final products are also high (61–84%). The procedure is applicable to a wide variety of functional groups including –OBn. [Copyright &y& Elsevier]

Abstract: The reaction mechanism of aryl alcohols and TosMIC (p-Toluenesulfonylmethyl isocyanide) catalyzed by InCl3 has been investigated by density functional theory (DFT). The geometries of reactants, intermediates, transition states, and products have been optimized at the B3LYP/6-31G(d) level. The vibration analysis has been performed to demonstrate the authenticity of transition states. The reaction processes are also confirmed by the changes of charge density at bond-forming critical point which analyzed by the atoms in molecules (AIM) theory. In addition, the nature bond orbital (NBO) analysis is carried out to discuss the bond nature and orbital interactions of the species in the reactions. Compared with that of the reaction without catalyst, the activation energy of that with InCl3 decreases by 339.55kJmol−1. Thus, the present computational results indicate that InCl3 is an effective catalyst. [ABSTRACT FROM AUTHOR]

Abstract: The nickel-2,2′-bipyridine catalyzed electrochemical cross-coupling reaction between an aryl halide and a chloropyridazine was investigated by an electrochemical study. The electrochemical behavior of the divalent nickel complex is affected by the presence of pyridazine rings which act as co-ligands of nickel. Cyclic voltammetry indicates that the cross-coupling reaction involves first a rapid oxidative addition of the chloropyridazine on the electrogenerated zerovalent nickel complex. The coupling product is then obtained by reaction with the aryl halide. [Copyright &y& Elsevier]

Abstract: An efficient synthesis of triarylmethanes has been developed via bisarylation of aryl aldehydes with arenes catalyzed by silica gel-supported sodium hydrogen sulfate in a solvent-free system. The new method features high yield, mild reaction conditions, and environmental friendliness. [Copyright &y& Elsevier]

Abstract: A highly efficient sp3–sp3 carbon–carbon bond formation system was developed for the aerobic ruthenium-catalyzed oxidative cross-dehydrogenative coupling reaction between tertiary amines and sp3 C–H compounds in the presence of RuCl3/O2, thus giving the corresponding α-functionalized amines. Compared with the reported method, H2O2 or t BuOOH was replaced successfully by economical and facile oxygen as the oxidant. Three types of activated C–H bonds for pronucleophiles were evaluated in this system. All these features combined are in accordance with important prospective green chemistry aspects. [Copyright &y& Elsevier]

Abstract: Under ‘open-flask’ and mild conditions, arenes condense smoothly with aromatic aldehydes in the presence of catalytic amount of FeCl3. The reaction tolerated a variety of substitutions and functional groups. This method provides a facile and direct access to symmetrical and unsymmetrical triarylmethane derivatives. [Copyright &y& Elsevier]

Abstract: CAN (cerium ammonium nitrate) and iodine can catalyze the reactions of indole or 1-methylindole with α,β-unsaturated ketone or aldehyde in DMSO/H2O (5:1) or ether solution at room temperature to obtain moderate to high yields of different products. [Copyright &y& Elsevier]

Abstract: In this study, the photo-catalytic oxidation process (UVCOP) for the removal of atrazine (ATZ) was successfully explored and the design charts for the optimization of the process were developed. The UVCOP was analyzed, mainly by using kinetic information to assist with the reaction mechanism and intermediates that were identified in this study. It was found that UVCOP greatly improves the removal of ATZ compared to sole-UV and dark-COP. In addition, a ‘compound effect’ is observed in the UVCOP, which supersedes the sum of the sole-UV and dark-COP. This compound effect was therefore investigated through the examination of the kinetic data of all of the three processes, and quantified in terms of the UV intensity and dosages of the reagent used. In addition, the enhancement index was introduced and verified. This is useful for verifying the effectiveness of the compound effect and the design of the UVCOP. [Copyright &y& Elsevier]

Abstract: The influence of two indole inhibitors on the hydrolysis reaction of l-dipalmitoylphosphatidylcholine (l-DPPC) catalyzed by phospholipase A2 (PLA2) has been studied in the coexistence region using surface pressure as function of time (π–t) and Brewster angle microscopy (BAM) measurements. Similar experiments have been performed with l-DPPC vesicles made by ultrasonication method using transmission electron microscopy (TEM). Comparing the π–t curves and BAM images, which show defected domains after a certain reaction time, as well as TEM images of defected vesicles, one can conclude that the two indole inhibitors have different abilities in reducing the activity of PLA2. The described experiments show that BAM and TEM can be successfully used to study the influence of newly designed inhibitors on the hydrolysis reaction catalyzed by PLA2. [Copyright &y& Elsevier]

The acylation of a variety of aromatic compounds with benzoyl chloride or its derivatives and catalytic amounts of Al2O3–ZrO2/S2O82− solid superacid affords the corresponding diaryl ketones in good to excellent yields 75–93% at appropriate temperature. [ABSTRACT FROM AUTHOR]

The direct, regioselective, and stereoselective arylation of activated alkynes with aryl iodides using a nickel catalyst and manganese reductant is described. The reaction conditions are mild (40 °C in MeOH, no acid or base) and an intermediate organomanganese reagent is unlikely. Functional groups tolerated include halides and pseudohalides, free and protected anilines, and a benzyl alcohol. Other activated alkynes including an amide and a ketone also reacted to form arylated products in good yields. [ABSTRACT FROM AUTHOR]

A gold (III) catalyzed stereoselective cycloisomerization of 5-disubstituted-5-hydroxypent-2-yn alkanoate is described. The mild and efficient reaction condition delivers a series of di , tri- substituted dihydrofuran derivatives with high yield s along with an impressive diastereoselectivity. The reaction proceeds via a double [3,3] sigmatropic rearrangement with a concomitant 5- endo - dig cyclization encompassing an allenyl intermediate. [Display omitted] [ABSTRACT FROM AUTHOR]