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A facile procedure for the synthesis of α-benzoxylated ketones through in situ oxidation of styrene derivatives and subsequent coupling with propiophenones or acetophenones is developed.

The development of a highly enantioselective catalytic oxa-Pictet–Spengler reaction has proven a great challenge for chemical synthesis. We now report the first example of such a process, which was realized by utilizing a nitrated confined imidodiphosphoric acid catalyst. Our approach provides substituted isochroman derivatives from both aliphatic and aromatic aldehydes with high yields and excellent enantioselectivities. DFT calculations provide insight into the reaction mechanism.

An efficient diastereoselective rhodium catalyzed synthesis of indolines possessing two contiguous tetrasubstituted carbon centers has been achieved with good to excellent yields using ortho-vinylanilines and iminocarbenes derived from N-sulfonyl-1,2,3-triazoles. The reaction affords excellent cis-diastereoselectivity through the initial formation of a N-ylide followed by intramolecular trapping with unactivated alkenes via an ene-type reaction with a well-organized transition state, namely intramolecular carbenylative amination of alkenes. The developed transformation was further extended to the successful synthesis of tricyclic compounds, imidazoindolines, through reduction and hypervalent iodine mediated oxidative cyclization.

Metal-free, p-toluenesulfonic acid (p-TSA)-mediated, straightforward propargylation of β-ketothioamides with aryl propargyl alcohol has been achieved at room temperature. In addition, the reaction also provided thiazole rings as byproducts. Furthermore, the propargylated thioamides undergo intramolecular 1,5-cyclization to afford fully substituted (hydro)thiophenes in the presence of base. Notably, the approach is pot, atom, and step economical (PASE).

An efficient solvent-free rapid transformation of amines to 9-fluorenylmethyloxycarbonyl protected amines derivatives (NHFmoc) is demonstrated using inexpensive and readily available Fmoc-Cl and moist imidazolium trifluoroacetateprotic ionic liquid as a powerful catalyst at ambient temperature. The scope of the chemo-selective protection strategy was successfully explored for the selective Fmoc protection of amino esters, amino alcohols, amino acids and amino phenol. The optically pure amino acids, amino acid esters and amino alcohols were efficiently converted into the corresponding N-Fmoc protected derivatives without racimization. Our study reveals that anionic part of the ionic liquid played vital role in the success of the protection of amines using Fmoc-Cl. The scope of the present method is extended for efficient benzyloxycarbonyl (Cbz, Z) protection of amines.

A metal- and peroxide-free N-acylation of anilines with 1,3-diketones with oxygen as oxidant yields the corresponding N-aryl amides under mild conditions.

Fe3O4-CTAB NPs have been applied as a competent catalyst for one-pot synthesis of nitriles directly from aldehydes. The present investigation describes the synthesis of nitriles by combination of aromatic/aliphatic/heterocyclic aldehydes and hydroxylamine hydrochloride in the presence of iron oxide nanocatalyst in DMF under reflux condition. Fe3O4-CTAB NPs were prepared by reported method and characterized by FE-SEM, TEM, and XRD analysis. The amount of Fe in Fe3O4-CTAB was quantified by Atomic Absorption Spectroscopy (AAS). The protocol endow with excellent yield of products along with simple reaction set up and economically adept alternative approach.

A unique copper-catalyzed binucleophilic switching of 2-aminopyridine has been developed for the regioselective synthesis of 2- and 3-iodoimidazo[1,2-a]pyridines using alkenes/alkynes as coupling partners in the presence of molecular iodine under aerobic reaction conditions. This method was also applied to the synthesis of 2-iodo-3-phenylbenzo[d]imidazo[2,1-b]thiazoles. This protocol offers an easy route towards the synthesis of 2,3-diarylimidazo[1,2-a]pyridines.

A metal-free and catalytic method for the synthesis of 2-substituted benzoxazoles and benzothiazoles from N-protected amino acids and carboxylic acids is described. The synthesis of benzoxazole on a solid support is demonstrated by the synthesis of benzoxazole attached to a human islet amyloid polypeptide, hIAPP22–27, fragment and benzoxazole derivatives of the side chain of aspartic acid on a modified fragment of Aβ18−21 (amyloid β) peptide. The reactions proceeded through a two-step mechanism. The coupling step is realized with a relatively new reagent, ethyl 2-cyano-2-(2-nitrobenzenesulfonyloxyimino)acetate (ortho-NosylOXY), and the cyclization step takes place thanks to an inexpensive organocatalyst, para-toluenesulfonic acid, under microwave irradiation. To the best of our knowledge, this is the first report of the complete synthesis of benzoxazole derivatives of a polypeptide on a resin solid support.

Herein, we report a convenient synthesis of aryl-substituted (E)-vinylic NH-sulfoximines via the Horner–Wadsworth–Emmons reaction without the use of protection–deprotection group strategies.

A convenient one-pot protocol for the synthesis of benzo-fused and indole-fused indolizines from Baylis–Hillman acetates was developed. This strategy involves CuBr/tert-butyl hydroperoxide promoted oxidation, intramolecular cyclization, and aromatization as key steps. The efficacy of this methodology was demonstrated by the formal synthesis of (±)-crispine A, a biologically active molecule.

A green and suitable protocol for the conversion of aldoximes into nitriles is described. The transformation is carried out under solvent-free conditions using FeCl3-silica medium. The protocol offers a green, single-step facile procedure with the use of less toxic metal salt to isolate nitriles in good to excellent yields.

An organocatalytic redox isomerization strategy has been developed for the synthesis of 1,4-ketoaldehydes. DABCO was found to be the best catalyst for the isomerization of γ-hydroxy enones. With 20 mol % of DABCO as catalyst and DMSO as the solvent high yields have been achieved for different 1,4-ketoaldehydes.

A ligand-free Pd-catalyzed approach has been developed for the synthesis of dibenzo-fused naphthyridines. The reaction involves a one-pot domino sequence of reactions involving C–H functionalisation and oxidation. The reaction was applicable to a wide range of substrates, giving the required product. Further fluorescence studies were performed where the Stoke's shift was found to be dependent on the polarity of the solvent.

Open-shell phenalenyl chemistry has widely been explored in the last five decades demonstrating its potential in various applications including molecular switch, spin memory device, molecular battery, cathode material, etc. In this article, we have explored another new direction of open-shell phenalenyl chemistry toward transition metal-free catalytic C–H functionalization process. A phenalenyl ligand, namely, 9-methylamino-phenalen-1-one (4a), promoted chelation-assisted single electron transfer (SET) process, which facilitates the C–H functionalization of unactivated arenes to form the biaryl products. The present methodology offers a diverse substrate scope, which can be operated without employing any dry or inert conditions and under truly transition metal based catalyst like loading yet avoiding any expensive or toxic transition metal. This not only is the first report on the application of phenalenyl chemistry in C–H functionalization process but also provides a low-catalyst loading organocatalytic ...

The copper-catalyzed aerobic oxidative synthesis of imidazo[1,5-a]pyridines via cascade denitrogenative transannulation reaction of pyridotriazoles with benzylamines with good functional group tolerance is developed. The present methodology is also applicable to amino acids to obtain imidazo[1,5-a]pyridines via decarboxylative oxidative cyclization.

An efficient and environmentally benign protocol for the synthesis of a new class of diversely functionalized novel 1 H -indol-3-yl-4 H -chromene-3-carbonitriles has been described through one-pot three-component condensation reaction of 3-(1 H -indol-3-yl)-3-oxopropanenitrile, 5,5-dimethylcyclohexane-1,3-dione, and various aldehydes in the presence of polystyrene-supported p -toluenesulfonic acid (PS/ P TSA) under solvent-free conditions. The present methodology offers several advantages such as short reaction time, simple operational procedure, avoid toxic solvent, high yield of product and endures the substrate diversity. The PS/ P TSA catalyst is readily available in stable form which is fairly inexpensive and can be easily recovered from the reaction medium without appreciable changes for further reuse in the consecutive reaction cycles effectively.

We report an efficient procedure for the synthesis of symmetrical disulfanes from organic thiocyanates in the presence of sodium in silica gel at room temperature. By avoiding the use of foul-smelling thiols, the present protocol provides an attractive alternative to existing methods for the preparation of symmetrical disulfanes.

One-pot synthesis of 1,2,3-triazole tethered benzimidazo[1,2-a]quinolines through a multi-component reaction is demonstrated. The domino/cascade reaction proceeds via click reaction, in which 1,2,3-triazole motif augment methylene group reactivity/N–C bond formation/Knoevenagel condensation in sequence. Overall one C–C bond and three C–N bonds are formed in a single step. In addition, photophysical properties of these new compounds were studied and compound 5u emerged as good fluorogenic substrate with quantum yield ∼0.21.

Various O and S-glycosyl esters and their corresponding acids are synthesized through a reaction of bromo sugar and benzyl glycolate in the presence of indium trichloride and indium tribromide as promoter. We discovered unprecedented catalytic effects of indium tribromide in glycosylation and hydrogenolysis in a one-pot operation. The sugar acid is a potential chiral auxiliary for the synthesis of biologically active compounds of diverse interests.

Copper-catalyzed regioselective C-3 sulfenylation of imidazo[1,2-a]pyridines using p-tosylchloride as a benign source of sulfenylating agents has been developed. On the other hand, p-tosylchloride mediated thiomethylation of imidazo[1,2-a]pyridines with dimethylsulfoxide as a source of thiomethylation under metal-free conditions was also described.

Diethyl carbonate (DEC) is a well-known linear organic carbonate that has wide applications. Besides its use as a fuel additive, DEC is an excellent electrolyte for lithium ion batteries and is used for the production of polycarbonates, which are globally used engineering plastics. The synthesis of DEC from CO2 helps in CO2 mitigation. It was earlier synthesized by phosgenation of ethanol, which is a toxic and dangerous process. Certain non-phosgene routes have been developed in recent years, which include oxidative carbonylation of ethanol, trans-esterification of carbonate, alcoholysis of urea, ethanolysis of CO2 and the ethyl nitrite route for DEC synthesis. This review underlines various non-phosgene methods for the synthesis of DEC by critically evaluating the catalysts used, operating conditions and mechanism of synthesis. The performances of various catalysts have been compared graphically along with the identification of problems and potential solutions. Certain engineering aspects, including kinetics and thermodynamics of the various routes, have also been highlighted. The shortcomings and research gaps have been explicitly mentioned and discussed along with required future developments and research work for DEC synthesis.

Novel, reusable, and efficient (Cd, Zn) S nanocatalysts were prepared by simple and economical chemical bath deposition using a greener approach. The as-synthesized catalysts were characterized by ...

A novel approach utilizing dual Morita–Baylis–Hillman (MBH) reactions in form of intermolecular and a chemo selective intramolecular version, has been developed. With three electrophilic and a nucleophilic site in precursor, selective condition for intramolecular MBH reaction has been optimized. Role of water was found to be crucial. The dual strategy was applicable for synthesis of a variety of medicinally and synthetically important piperidine unit whose 5/6 atoms of ring were substituted, featuring a stereo defined trisubstituted olefin, a Michael acceptor (with a methylene moiety), trivalent nitrogen and a tertiary alcohol.

A four component one-pot reaction between aromatic aldehyde, malononitrile, ammonium acetate and ketone mediated by Ag(I) N-heterocyclic carbene to produce multisubstituted and fused pyridines in a short reaction time (∼10 min) in ethanol at room temperature is described.

ConspectusN-Heterocyclic carbenes (NHCs) are known to stabilize some metal atoms in different oxidation states mostly by their strong σ-donation. After the successful syntheses of cyclic alkyl(amino) carbenes (cAACs), they have been proven to be much more effective in stabilizing electron rich species. In cAAC, one of the σ-withdrawing and π-donating nitrogen atoms of NHC is replaced by a σ-donating quaternary carbon atom leading to a lower lying LUMO. This makes the acceptance of π-back-donation from the element bound to the carbene carbon atom of cAAC energetically more advantageous. Further evidence suggests that the carbene carbon of cAAC can use the lone pair of electrons present on the adjacent nitrogen in a more controlled way depending on the accumulation of electron density on the bound metal. It has been found that cAAC can be utilized as excellent ligand for the stabilization of a complex with three coordinate metal center [(cAAC)2MI-Cl; M = Fe, Co, Cr]. Complex (cAAC)2MIICl2 [M = Fe, Co, Cr] w...

Review: comprehensive survey of the synthesis and chemistry of the title nitrile covering the literature published during 2005-2014; 70 refs.

The title compound is synthesized by solid state reaction of a stoichiometric mixture of BaCO3 and TeO2 (air, 550 °C for 6 h, and 650 °C for 12 h).

A green method for the transamidation and thioamidation using H-β-zeolite as heterogeneous recyclable catalyst is developed.

Radicals are an important class of species which act as intermediates in numerous chemical and biological processes. Most of the radicals have short lifetimes. However, radicals with longer lifetimes can be isolated and stored in a pure form. They are called stable radicals. Over the last five decades, the syntheses of several stable radicals have been reported. Recently, highly unstable radicals have been successfully stabilized via strong σ-donation of singlet carbenes. Cyclic aklyl(amino) carbene (cAAC) is regarded as a stronger σ-donor and a better π-acceptor when compared with that of an N-heterocyclic carbene (NHC). In this article we review preferentially the results of our group to generate stable radical centers on the carbene carbon atoms by employing the so far hidden and unique ability of the cAACs. We focus on the development of new synthetic routes to stable and isolable radicals containing silicon atoms. All the compounds have been well characterized by single crystal X-ray analysis; the mono-radicals have been distinguished by EPR spectroscpy and the ground state of the diradicals has been studied by magnetic susceptibility measurements and theoretical calculations. Many of these compounds are studied by cyclic voltammetry and are often converted to their corresponding radical cations or radical anions via electron abstraction or addition processes. Some of them are stable, having long lifetimes and hence are isolated and characterized thoroughly. Not much information has been obtained on the short lived persistent radical species. Herein, we discuss some of the examples of such a type of species and focus on what kind of chemical reactions are initiated by these short-lived radical species in solution. We also briefly mention the syntheses and charaterization of the so far reported stable silicon centered radicals.

A simple and efficient one-pot microwave-assisted click formation of 1-(substituted)-1H-1,2,3-triazol-4-yl)methyl)diphenylphosphineoxide derivatives via Huisgen regioselective [3+2]-cycloaddition of an in situ generated organic azides and diphenyl(prop-2-yn-1-yl)phosphine oxide in highly polar DMSO-H2O medium. This synthetic protocol is mild, requires shorter reaction time, and afforded products in excellent yields with high regioselectivity.

Heterogeneous Cu-MnO-catalyzed selective monohalogenation of aromatic compounds with cheap N-halosuccinimide (NXS) as a halogenating agent in the presence of molecular oxygen as an oxidant, under irradiation with visible light is reported. Monochlorination, bromination, and iodinations were achieved in a highly selective fashion. Our developed heterogeneous Cu-MnO catalyst without any additive and ligands works well for halogenation with electron-rich substrates and also works selectively with electron poor substrates. Moreover, chlorination occurs efficiently with the more challenging substrates benzoic esters. The heterogeneous nature of the reaction was proven by hot filtration test.

The potential medicinal applications of boron-based compounds have been well established. Among the medicinal applications of boron, its use for the treatment of cancer via boron neutron capture therapy (BNCT) is the most promising. Although a variety of approaches have been evaluated for adequate boron delivery to the cancer tissues for successful cancer therapy, this review focuses on the synthesis of carbohydrate-based boron delivery platforms. Recent advances in the synthesis and utilization of glycoconjugates for boron delivery has been reported.

The first catalytic enantioselective 1,4-iodofunctionalizations of conjugated dienes have been developed. Starting from β,γ,δ,e-unsaturated oximes and 4-Ns hydrazones, these N-iodosuccinimide-mediated reactions are catalyzed by newly modified tertiary aminothiourea derivatives and furnish Δ2-isoxazoline and Δ2-pyrazoline derivatives, respectively, containing an (E)-allyl iodide group at the quaternary stereogenic center generally in high yield and with excellent enantioselectivity (up to 98.5:1.5 er).

MIII(WVIO2)2 (P2O7)(PO4) (M: Sc, V, Cr, Fe, Mo, Ru, Rh, In, Ir) are obtained via vapor phase moderated solid state reactions of P4O10, WVOPO4, β-VOPO4, and trivalent transition metal phosphates using PtCl2 as mineralizer and Cl2 source (evacuated silica tubes, 1.

We report here, the drug conjugation and release characteristics of a multifunctional composite material made of magnetically active γ-Fe 2 O 3 nanoparticles and optically active mesoporous ZnO nanoparticles. It has been observed that mesoporous ZnO uptake around 86% of the anti cancer drug, daunorubicin hydrochloride, rapidly (within 60 min) and the γ-Fe 2 O 3 helps in separating the drug loaded composite nanomaterials from solution for further characterization. The unaltered emission spectral characteristics of the drug molecule indicate successful incorporation into the composite matrix. We also monitored the release of the drug, with and without ultrasonic irradiation. It has been observed that in both cases the amount of drug released was higher in the acidic pH, thereby confirming its potential in anti cancer drug delivery applications. The prepared nanocomposite of γ-Fe 2 O 3 and mesoporous ZnO exhibited multifunctionality, could load larger amount of daunorubicin hydrochloride in a very short time and also could control the drug release under sonication thereby making it an ideal material for drug delivery applications. The presence of a high saturation magnetization value along with visible emission makes this composite an ideal multifunctional material for drug loading studies.

A simple and efficient method for the synthesis of primary allylic alcohols from monosubstituted epoxy acetates has been developed using titanocene(III) chloride mediated epoxide ring opening via acetate elimination. The radical chemistry has become an inevitable tool to the organic chemists now a days for the formation of carbon-carbon bonds. Prolific use of this particular field of chemistry is well established and growing continuously for the synthesis of carbocyclic as well as heterocyclic natural products 1 . High stereo-and regioselectivity and mildness of the radical technique unaffecting various sensitive functional groups makes it a common tool for the synthesis of important organic molecules 2 . Titanocene(III) chloride (Cp2TiCl) mediated selective homolytic epoxide ring opening 3 has established a new era of developing new methodologies for various synthetic strategies eventually leading to numerous biologically active natural products. Radical generated by epoxide ring cleavage takes part in intra-or inter- molecular reaction including cascade pathway 4 with an electrophilic radical acceptor depending on either the mode of the reaction or the substrate framework. The commonly used radical acceptors are carbonyl groups or double and triple bonds. But the outcome of this array of reactions is mainly inter or intra- molecular addition products, with some rare and isolated examples of elimination reactions 5 . Most of the reported transformations deal either with cyclic epoxy alcohols and acetates in carvone systems 5c-d or di, tri and tetra substituted epoxy alcohols 5a-b . However, such type of transformations are yet to be explored for the monosubstituted 2,3-epoxy alcohols and acetates. Herein is reported a mild and simple methodology for the synthesis of primary allylic alcohols by Cp2TiCl mediated epoxide ring opening of monosubstituted epoxy acetates via the acetate elimination reaction as well as the experimental investigation to establish the mechanism of the reaction. Titanocene(III) chloride (Cp2TiCl) was prepared from commercially available Cp2TiCl2 and Zn dust in THF under argon. Some of our results differ from the reported works as may be realized from the following discussion.

N′-Vinyl sulfonimidamides have been synthesized through a Pd-catalyzed C–N cross coupling between the N′-(imine nitrogen) of N′-deprotected sulfonimidamides and vinyl bromides. The hitherto unreported products were obtained in moderate to excellent yield, and the C–C double bond geometry of the vinylic substrates were retained during the course of reaction. Single crystal X-ray crystallographic analysis confirmed the product structure. Furthermore, we demonstrate that the formed N′-vinyl sulfonimidamides could undergo hydrogenation with Pd–C/H2 to provide N′-alkyl sulfonimidamides.

Intramolecular Morita–Baylis–Hillman and Rauhut–Currier reactions are important tools which have constantly grown over several years. This review summarizes and highlights their various aspects such as development of activated alkenes, electrophiles and catalysts both in achiral and chiral fashion, use of non conventional electrophiles, applications in total synthesis. Selected miscellaneous reports of internal promoters, cycloadditions, and non conventional routes for IMBH adduct have also been presented, along with future projections.

An Ortoleva—King reaction of pyridineacetate and ketones followed by intramolecular Aldol condensation under mild reaction conditions affords indolizine-1-carboxylates.

Iron(III)-mediated radical nitration of bisarylsulfonyl hydrazones is described. In this protocol, the nontoxic and inexpensive Fe(NO3)3·9H2O plays a dual role as catalyst as well as nitro source. The mild conditions, broad substrate scope, and the functional group compatibility are the significant features. The reaction pathway has been demonstrated using DFT calculations, and the products can be subsequently converted into oximes using SnCl2·2H2O in high yields.

Activation of 1-acetylcycloalkenes for asymmetric Michael addition to an electrophile like nitroolefins by an amine organocatalyst is reported for the first time.