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The use of inherent redox couplets in PrVO4 for the one-pot synthesis of 2,3-disubstituted quinolines through the oxidative tandem reaction of 2-aminobenzylalcohols with 1,3-dicarbonyl compounds has been demonstrated.

An efficient protocol for the synthesis of symmetrical and unsymmetrical 2,4,6-trisubstituted pyridines via oxidative cascade annulation of arylacetylenes with benzylamines has been developed. The reaction proceeds smoothly utilizing iron(II) triflate as a catalyst and molecular oxygen as an oxidant with broad substrate scope. Mechanistic studies reveal that the reaction may be experiences an oxidative condensation followed by double alkynylation and amination process.

A versatile approach for the synthesis ofN-(4-methylbenzyl)benzamide, C15H15NO, using CuI as catalyst has been reported. Single crystals of the synthesized compound were grown using the slow evaporation solution technique. The crystal structure of theN-(4-methylbenzyl)benzamide crystals has been determined by single-crystal X-ray diffraction. The compound crystallizes in an orthorhombic lattice, noncentrosymmetric space groupPna21. The crystal structure is stabilized by intermolecular N—H...O hydrogen bonds and weak C—H...π interactions to form layers parallel to theaaxis. A user-friendly approach based on centre of mass propagation vector theory was used to predict the crystal morphology. The framework developed here utilizes the concept of intermolecular bond strength to discern the crystal morphology. Fourier transform IR, NMR and high-resolution mass spectrometry analytical techniques were used for the identification of functional groups and confirmation of the structure of the title compound. All of the intermolecular interactions present in the crystal structure, including the C—H...π, C—H...O and N—H...O interactions, were investigated and confirmed by molecular Hirshfeld surface analysis. From linear optical spectroscopy, the transmittance, optical band gap and UV cutoff wavelength were determined. The photoluminescence emission spectrum was recorded for a grown crystal. Dielectric measurements were performed at room temperature for various frequencies. The mechanical strength of the (001) plane of the title compound was measured using the Vickers micro-hardness technique. A piezo-coefficient of 15 pC N−1was found along the (001) plane of the title crystals. The thermal stability and melting point were also investigated. In addition, density functional theory simulations were used to calculate the optimized molecular geometry and the UV–vis spectrum, and to determine the highest occupied molecular orbital/lowest unoccupied molecular orbital energy gap. The results show thatN-(4-methylbenzyl)benzamide is a potential candidate for multifunctional optical and piezoelectric crystals.

In the current study, we fabricated a microspherical core-shell consisting of MoO2 and graphitic-C3N4 by a simple one-step calcination procedure. TEM analysis revealed MoO2 at the core (average diameter of 210 nm), surrounded by a graphitic-C3N4 shell. MoO2 of the core exhibited monoclinic symmetry. The Raman spectrum additionally confirmed the monoclinic MoO2. The sample was EPR active, indicating paramagnetic oxygen vacancies. It contained meso-sized pores and a high surface area. The core-shell’s optical bandgap was higher than the pure metallic MoO2. XPS results confirmed the existence of molybdenum in IV and VI oxidation states. The core-shell’s heterojunction catalyzed the degradation of xylenol orange (XO) dye into C8H9ONH3+, C6H5SO3− and C15H14ONH3+SO3−. The core-shell promoted the efficient synthesis of symmetrical and unsymmetrical 2, 4, 6-triaryl pyridines through the oxidative condensation of acetophenones with benzylamines in good to excellent yields using molecular oxygen as the oxidant. The catalyst is recyclable for both these reactions.

The synthesis of imines by oxidative self- or cross-condensation of primary amines has been achieved using iron(II) bromide as the catalyst. The protocol is ligand-free, additive-free, solvent-free, and high-yielding and utilizes renewable oxygen as sole oxidant. The reaction tolerated a wide range of functionalities.

A novel route for synthesis of bis(indolyl)methanes has been developed by the oxidative coupling of benzylamines and indoles in the presence of iron(II) triflate as a catalyst and molecular oxygen as an oxidant. This method promises versatility, cost-effectiveness, and efficiency.

An iron(II) bromide-catalyzed oxidative coupling of benzylamines with 2-amino/hydroxy/mercapto-anilines has been developed, allowing the synthesis of a diversity of substituted 1,3-benzazoles in good to excellent yields. This transformation is compatible with a wide range of functional groups. The method is practical, economical and employs molecular oxygen as an oxidant.

A novel approach to construct 2-aryl/heteroaryl quinazolines was developed through an iron-catalyzed cascade reaction of 2-aminobenzyl alcohols with benzylamines under aerobic oxidative conditions. The reaction proceeds via the formation of N-benzylidenebenzylamines followed by oxidative trapping of ammonia/intramolecular cyclization in a one-pot manner. This method exhibits a broad substrate scope and a high tolerance level for sensitive functional groups, and is amenable to gram scale synthesis.

Fluoride doping in the CeO2 lattice has been achieved by a simple, reliable, reproducible, and safe solution-based method. F-containing CeO2 has retained the fluorite structure, and its effect has been confirmed from various analytical techniques such as powder X-ray diffraction, Fourier transform IR, Raman, UV-visible diffuse reflectance, photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS), scanning electron microscopy-energy-dispersive X-ray (EDX) and transmission electron microscopy-EDX analysis. The concentration of fluoride in the CeO2 lattice has been determined from chemical analysis and core-level XPS analysis. The concentration of Ce(3+) in the F-doped and undoped CeO2 samples have been determined both from XPS analysis as well as from variable-temperature magnetic susceptibility measurements. The characteristic Ce(3+) emission in the PL spectrum indicated the increase of Ce(3+) ion concentration in the F-doped sample, conforming to the results from XPS and magnetic measurements. F-doped CeO2 nanocrystals showed moderate monodispersity as determined from particle-size measurements using dynamic light scattering experiments and high surface area of 106.1 m(2)/g. Optical band gap of CeO2 has narrowed upon doping with fluoride ions from 3.05 to 2.95 eV. The formation of extrinsic oxygen vacancy complexes upon F-doping has been observed in the Raman spectrum (at 1097 cm(-1)) in addition to fingerprint bands of CeO2. The UV-shielding property and photocatalytic inactivity toward aqueous dye degradation process of F-doped CeO2 has suggested its potential use in cosmetic applications. Both F-doped CeO2 and CeO2 have been used as catalysts for oxidative coupling of benzylamines to imines in the presence of molecular oxygen under solvent-free conditions. F-doped CeO2 exhibited better catalytic efficiency than CeO2. The oxidation procedure using these catalysts is simple, environmentally benign, and solvent-free, and the catalysts are reusable.

In the early eighties, we introduced samarium diiodide for the transformation of various functional groups. Since then, this reducing agent has been extensively used for the reductive cleavage of single bonds, C-C bond formations, C-N bond formations, and β-elimination reactions. In this Personal Account, we highlight our initial results, as well as some of the contributions from various research groups. Because of space limitations, we arbitrarily select some useful results that have recently been described in literature.

A copper-catalyzed oxidative coupling reaction of o-phenylenediamines with 2-aryl/heteroarylethylamines using molecular oxygen as an oxidant has been developed. This approach provides a practical and direct access to construct quinoxalines in excellent yields at room temperature. The reaction has a broad substrate scope and exhibits excellent functional-group tolerance. This method could be easily scaled up and applied to the synthesis of biologically active molecules bearing a quinoxaline structural scaffold.

Molecular organic single crystals of bis(L-asparaginium hydrogensquarate) monohydrate [BASQ; (C8H10N2O7)2·H2O] have been grown by solution technique. Crystallographic information was investigated by single-crystal X-ray diffraction (SCXRD) analysis. Hirshfeld surface and fingerprint plot studies were performed to understand the intermolecular interactions of the BASQ crystal in graphical representation. Functional group identification was studied with FT–IR (Fourier transform–IR) spectroscopy. The positions of proton and carbon atoms in the BASQ compound were analyzed using NMR spectroscopy. High transparency and a wide band gap of 3.49 eV were observed in the linear optical study by UV–vis–NIR spectroscopy. Intense and broad photoluminescence emissions at room temperature were observed in blue and blue–green regions. The frontier molecular orbitals of the BASQ molecule were obtained by the DFT/B3LYP method employing 6-311G** as the basis set. The dielectric study was carried out with temperature at various frequency ranges. The piezoelectric charge coefficient (d33) value of BASQ crystal was found to be 2 pC/N, which leads to its application in energy harvesting, mechanical sensors and actuators applications. In the non-linear optical study, the BASQ crystal showed promising SHG conversion efficiency. Mechanical properties of the BASQ crystal were studied experimentally by Vicker's microhardness technique, which revealed that the grown crystal belonged to the softer category. BASQ crystal void estimation reveals the mechanical strength and porosity of the material.

The origin of nonlinear effects (no proportionality between enantiomeric excess (ee) of chiral auxiliary and ee of product) is first summarized in general terms, underlining the importance of the presence of molecular species bearing several moieties deriving from the chiral auxiliary. The presence of a heterochiral species, produced from enantioimpure chiral auxiliaries, usually explains well the deviation to linearity, especially asymmetric amplification. In this article it is shown that the absence of a heterochiral species is not incompatible with an asymmetric amplification. The demonstration has been done on a simple model, the equilibrium of homochiral dimerization. The monomers R and S being in equilibrium with the dimers R(2) and S(2), it was possible to calculate ee(monomer) and ee(dimer) as a function of the initial concentration and the initial ee of the monomer. The asymmetric amplification can be quite substantial for the dimer, while asymmetric depletion characterizes the residual monomers. Similar conclusions apply to homochiral tri- and tetramerizations. The extension to irreversible reactions was briefly analyzed as well as the use of these results.

Evidence for the generalized anomeric effect (GAE) in the N-acyl-1,3-thiazolidines, an important structural motif in the penicillins, was sought in the crystal structures of N-(4-nitrobenzoyl)-1,3-thiazolidine and its (2:1) complex with mercuric chloride, N-acetyl-2-phenyl-1,3-thiazolidine, and the (2:1) complex of N-benzoyl-1,3-thiazolidine with mercuric bromide. An inverse relationship was generally observed between the. C-2-N and C-2-S bond lengths of the thiazolidine ring, supporting the existence of the GAE. (Maximal bond length changes were similar to 0.04 angstrom for C-2-N-3, S-1-C-2, and similar to 0.08 angstrom for N-3-C-6.) Comparison with N-acylpyrrolidines and tetrahydrothiophenes indicates that both the nitrogen-to-sulphur and sulphur-to-nitrogen GAE's operate simultaneously in the 1,3-thiazolidines, the former being dominant. (This is analogous to the normal and exo-anomeric effects in pyranoses, and also leads to an interesting application of Baldwin's rules.) The nitrogen-to-sulphur GAE is generally enhanced in the mercury(II) complexes (presumably via coordination at the sulphur); a 'competition' between the GAE and the amide resonance of the N-acyl moiety is apparent. There is evidence for a 'push-pull' charge transfer between the thiazolidine moieties in the mercury(II) complexes, and for a 'back-donation' of charge from the bromine atoms to the thiazolidine moieties in the HgBr2 complex. (The sulphur atom appears to be sp(2) hybridised in the mercury(II) complexes, possibly for stereoelectronic reasons.) These results are apparently relevant to the mode of action of the penicillins. (c) 2006 Elsevier B.V. All rights reserved.

A novel route for synthesis of bis(indolyl)methanes has been developed by the oxidative coupling of benzylamines and indoles in the presence of iron(II) triflate as a catalyst and molecular oxygen as an oxidant. This method promises versatility, cost-effectiveness, and efficiency.

2-Amino/hydroxy/mercapto-anilines react with benzylamines via oxidative coupling using molecular oxygen as oxidant leading to various substituted 1,3-benzazoles.

In the early eighties, we introduced samarium diiodide for the transformation of various functional groups. Since then, this reducing agent has been extensively used for the reductive cleavage of single bonds, C-C bond formations, C-N bond formations, and β-elimination reactions. In this Personal Account, we highlight our initial results, as well as some of the contributions from various research groups. Because of space limitations, we arbitrarily select some useful results that have recently been described in literature.

When ketoximes admixed with solid metaboric acid (formed from boric acid at 100degreesC/0.1 Torr) are heated (similar to 140degreesC/7-42 h), the corresponding amides or lactams are produced in excellent yields (62-92%) via the Beckmann reaction. Aromatic aldoximes undergo both dehydration to the nitrile as well as (non-stereospecific) rearrangement under the above conditions. The absence of solvent, and the mildness and low toxicity of boric acid, characterise the present procedure. CO. 2002 Elsevier Science Ltd. All rights reserved.

Several ketoxime hydrochlorides undergo Beckmann rearrangement upon heating below their melting points for 5-48 h, in excellent yields (generally >70%). The absence of a reaction solvent and of by-products (except for HCl) makes for a very simple work-up. Aldoxime hydrochlorides apparently undergo dehydration to the corresponding nitriles under the above conditions. Dibenzyl ketoxime hydrochloride unexpectedly furnished a pyrazine derivative (67%), presumably via further reaction of the intermediate nitrilium ion in the crystal lattice.

Several ketoxime hydrochlorides undergo Beckmann rearrangement upon heating below their melting points for 5-48 h, in excellent yields (generally >70%). The absence of a reaction solvent and of by-products (except for HCl) makes for a very simple work-up. Aldoxime hydrochlorides apparently undergo dehydration to the corresponding nitriles under the above conditions. Dibenzyl ketoxime hydrochloride unexpectedly furnished a pyrazine derivative (67%), presumably via further reaction of the intermediate nitrilium ion in the crystal lattice.

Ketoximes and aromatic aldoximes are converted to the corresponding carbonyl compounds in excellent yields (67–97%), upon treatment with a suspension of iodic acid in dry $CH_2Cl_2$ at room temperature

When ketoximes admixed with solid metaboric acid (formed from boric acid at 100degreesC/0.1 Torr) are heated (similar to 140degreesC/7-42 h), the corresponding amides or lactams are produced in excellent yields (62-92%) via the Beckmann reaction. Aromatic aldoximes undergo both dehydration to the nitrile as well as (non-stereospecific) rearrangement under the above conditions. The absence of solvent, and the mildness and low toxicity of boric acid, characterise the present procedure. CO. 2002 Elsevier Science Ltd. All rights reserved.

Samarium diiodide may be a useful reagent in a step of an asymmetric synthesis process. It can release a blocking group in mild conditions, as described in several examples. SmI2 has been used as electron donor in many C–C bond formations in presence of a chiral auxiliary. It can also generate samarium enolates which were subjected to asymmetric protonation. The examples selected in this review of SmI2 methodology concern only the cases where the chiral auxiliary is not retained in the final product.

A variety of ketones can be directly converted into the secondary amides expected from a Beckmann rearrangement of the corresponding oximes in high yield, by heating them with hydroxylamine hydrochloride and anhydrous oxalic acid at similar to 100degreesC for 4-12 h. (Aromatic aldehydes afforded mixtures of nitrile and amide.) The transformation is apparently (kinetically) driven by the coupled decomposition of oxalic acid (to CO+CO2) via the fragmentation of an intermediate oxime mono-oxalate. However, an alternative pathway, mechanistically analogous to the Schmidt reaction, is not only equally likely but may well be general for the Beckmann rearrangement.

An unusual secolignan glycoside, juspurpurin (1), and a new arylnaphthalene glycoside, justalakonin (2), together with eight known lignans were isolated from the whole plants of Justicia purpurea. Compound 1 is the first glycoside of a rare group of secolignans. The structures of the new compounds 1 and 2 were established using 1D and 2D NMR ((1)H-(1)H COSY, HMQC, and HMBC) spectral data and by chemical transformations.

(A) Oxalic acid is an efficient reagent for the Beckmann reaction - a variety of ketoximes are converted into the corresponding secondary amides by classical anti-periplanar migration upon heating to ca. 100 °C, and aldoximes afford the corresponding nitriles. The procedure offers high yield of the desired products, gaseous byproducts $(CO + CO_2)$ and the absence of reaction solvent. (B) Anhyd. oxalic acid is an excellent mediator for one-pot transformation of ketones to amides in the presence of hydroxylamine hydrochloride. The method is effective for various arom. and aliph. ketones, and provides excellent yield of the products. (C) In the presence of aq. oxalic acid, enol ethers undergo expeditious hydrolysis to the corresponding ketones without concomitant migration of the double bond. In contrast, use of a mineral acid typically gives the conjugated ketone. This method offers considerable advantage in terms of regioselectivity of the product.

A variety of ketoximes undergo the Beckmann rearrangement when heated with 0.5 molar equiv. of chloral (neat melt/1\sim30°C), to furnish the corresponding amides in excellent yields (generally 80–95%) after simple work-up. (Aromatic aldoximes dehydrated to the corresponding nitriles in excellent yields under similar conditions.) The absence of solvent, Bronsted acids, strong Lewis acids and by-products, and a simple work-up characterise the procedures.

Ketoximes and aromatic aldoximes are converted to the corresponding carbonyl compounds in excellent yields (67–97%), upon treatment with a suspension of iodic acid in dry $CH_2Cl_2$ at room temperature

The main classes of asymmetric synthesis are retrieved. Then the historical developments in the attempts to prepare enantiomerically enriched compounds are detailed. The conceptual and experimental contributions of the main pioneers from the time of Pasteur until the First World War have been addressed.

Samarium diiodide may be a useful reagent in a step of an asymmetric synthesis process. It can release a blocking group in mild conditions, as described in several examples. SmI2 has been used as electron donor in many C–C bond formations in presence of a chiral auxiliary. It can also generate samarium enolates which were subjected to asymmetric protonation. The examples selected in this review of SmI2 methodology concern only the cases where the chiral auxiliary is not retained in the final product.

Ketoximes and aldoximes are expeditiously prepared by the reaction of the corresponding carbonyl compound with hydroxylamine hydrochloride in dimethylformamide, in the presence of a sub-stoichiometric quantity of glycine at room temperature. Mild (non-hydroxylic) conditions, simple workup and high yield characterise the methodology.