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Amino sugars are important constituents of a number of biomacromolecules and products of microbial secondary metabolism, including antibiotics. For most of them, the amino group is located at the positions C1, C2 or C3 of the hexose or pentose ring. In biological systems, amino sugars are formed due to the catalytic activity of specific aminotransferases or amidotransferases by introducing an amino functionality derived from L-glutamate or L-glutamine to the keto forms of sugar phosphates or sugar nucleotides. The synthetic introduction of amino functionalities in a regio- and stereoselective manner onto sugar scaffolds represents a substantial challenge. Most of the modern methods of for the preparation of 1-, 2- and 3-amino sugars are those starting from "an active ester" of carbohydrate derivatives, glycals, alcohols, carbonyl compounds and amino acids. A substantial progress in the development of region- and stereoselective methods of amino sugar synthesis has been made in the recent years, due to the application of metal-based catalysts and tethered approaches. A comprehensive review on the current state of knowledge on biosynthesis and chemical synthesis of amino sugars is presented.

Financial support by Consolider-Ingenio 2010 (project MULTICAT), Spanish MICINN (Projects MAT2011-28009 and CTQ-2011-27550) and Program Severo Ochoa are gratefully acknowledged.

Solid catalysts can be an alternative to homogeneous mineral Bronsted and Lewis acids for the synthesis of pharmaceuticals provided that the diffusional and adsorption properties of the reactants and products can be controlled. Structured micro and especially monolayered zeolites and mesoporous materials can be active and selective for intramolecular cyclization reactions and, more specifically, for intramolecular aza-Michael cyclizations of 2′-aminochalcones to yield aryl-2,3-dihydro-4(1 H)-quinolinones of pharmaceutical interest. However, the catalyst deactivates by strong adsorption of the basic quinolinone product. Product desorption has been controlled by optimizing catalyst pore structure and surface composition, together with a proper selection of solvent and reaction temperature. Process intensification for the synthesis of aryl-2,3-4(1 H)-quinolinones of pharmaceutical interest has been achieved by preparing catalysts that allow the one-pot synthesis of the dihydroquinolinones starting from 2′-nitrochalcones with excellent yields.

Several solid catalysts are tested for the selective synthesis of nitriles by dehydration of aldoximes.

High-temperature superconductivity in iron pnictides and chalcogenides emerges when a magnetic phase is suppressed. The multi-orbital character and the strength of correlations underlie this complex phenomenology, involving magnetic softness and anisotropies, with Hund's coupling playing an important role. We review here the different theoretical approaches used to describe the magnetic interactions in these systems. We show that taking into account the orbital degree of freedom allows us to unify in a single phase diagram the main mechanisms proposed to explain the ( π , 0 ) order in iron pnictides: nesting-driven superconductivity, exchange between localised spins, and Hund-induced magnetic state with orbital differentiation. Comparison of theoretical estimates and experimental results helps locate the Fe superconductors in the phase diagram. In addition, orbital physics is crucial to address the magnetic softness, the doping-dependent properties, and the anisotropies.

This article aims to show the identity of “circularly polarized luminescent active simple organic molecules” as a new concept in organic chemistry due to the potential interest of these molecules, as availed by the exponentially growing number of research articles related to them. In particular, it describes and highlights the interest and difficulty in developing chiral simple (small and non-aggregated) organic molecules able to emit left- or right-circularly polarized light efficiently, the efforts realized up to now to reach this challenging objective, and the most significant milestones achieved to date. General guidelines for the preparation of these interesting molecules are also presented.

A three-step procedure involving Diels–Alder condensation of maleic anhydride with furane, formation of N-substituted imide upon reaction with appropriate diamine, and a final retro Diels–Alder regeneration of the maleic carbon–carbon double bond is proposed for an unequivocal synthesis of N-substituted basic maleimides. The novel method is characterized by mild reaction conditions, easy work-up, high yields, and no need for additional catalysis.

Negishi reactions of 3-halogen and 3,5-dihalogen substituted BODIPYs with different organozinc reagents are reported as the first examples of this valuable palladium-catalyzed C–C coupling reaction into the family of the BODIPY dyes. It is demonstrated that the Negishi coupling is especially useful for obtaining interesting alkylated BODIPYs, including synthetically-valuable asymmetrically-3,5-disubstituted BODIPYs.

Thioaniline and 1,3-diphenylpropenone react to benzothiazepine in the presence of alumosilicates.

Palladium on magnesium oxide is able to allow a one-pot reaction to synthesize thioethers from thiols and aldehydes formed in situ from the respective alcohol by means of a borrowing hydrogen method. The reaction is initiated by dehydrogenation of the alcohol to give a palladium hydride intermediate and an aldehyde. The latter reacts with a thiol involving most probably the intermediacy of a thionium ion RCHS+R, which can be reduced in situ by the metal hydride to afford thioethers.

Process intensification by using well-defined solid catalysts able to perform one-pot multistep reactions is one of the open fronts in heterogeneous catalysis. This is even more relevant if new, more efficient synthesis routes are open. Herein, a gold catalyst was used to synthesize benzimidazoylquinoxalines compounds by two efficient and selective novel methods in a multistep one-pot methodology. The first method involved the synthesis of benzimidazoylquinoxaline compounds with the same substituents in both heterocycles through oxidation–cyclization of glycerol with o-phenylenediamine derivatives, whereas the second one allowed the synthesis of benzimidazoylquinoxalines compounds with different substituents in each aromatic ring through coupling of o-phenylenediamine derivatives with glyceraldehyde in a first stage to produce the benzimidazol compound as an intermediate, followed by an oxidation–cyclization with another o-phenylenediamine compound in a second stage. Both stages were performed by using gold nanoparticles supported on nanoparticulated ceria (Au/CeO2) as the catalyst and air as the oxidant, in absence of any homogeneous reagent. A reaction mechanism has been proposed.

In contrast to previous studies Knoevenagel condensation reaction of methyl-substituted BODIPYs provides the corresponding 8-alkenyl derivatives.

The superior catalytic activity of the newly synthesized NHC-catalyst is attributed to steric factors.

Organic synthesis performed through multicomponent reactions is an attractive area of research in organic chemistry. Multicomponent reactions involve more than two starting reagents that couple in an exclusive ordered mode under the same reaction conditions to form a single product which contains the essential parts of the starting materials. Multicomponent reactions are powerful tools in modern drug discovery processes, because they are an important source of molecular diversity, allowing rapid, automated and high throughput generation of organic compounds. This review aims to illustrate progress in a large variety of catalyzed multicomponent reactions performed with acid, base and metal heterogeneous and homogeneous catalysts. Within each type of multicomponent approach, relevant products that can be obtained and their interest for industrial applications are presented.

In this Critical Review, we discuss how carbohydrates can be transformed into a variety of chemicals through heterogeneous catalysis. We focus particularly on oxidation, reduction and dehydration of hexoses, as well as one-pot reactions of di- and polysaccharides. Most of the reactions involve heterogeneous catalysts, although some interesting homogeneously catalyzed processes are also included.

A.L.-P. thanks CSIC for a contract under the JAE-doctor program. Financial support by PLE2009 project from MCIINN and Consolider-Ingenio 2010 (proyecto MULTICAT) are also acknowledged.

The triplet-sensitized photolysis of dienic aldehydes of type (I) and (III) is investigated in the presence of 4-phenylbenzophenone as sensitizer.

High degree of diastereoselectivity is observed in the reaction leading to (E)-cyclopropanols.

Reactions of four aldehydes with five aromatic compounds have been carried out on a series of USY zeolites with unit cell size in the 24.56 to 24.25-t1 range. Conversion decreased in the order formaldehyde > benzaldehyde > acetaldehyde > propionaldehyde and also in the series anisole > toluene > benzene > chlorobenzene. For aliphatic aldehydes a mixture of ortho-ortho', ortho-para', and para-para' diarylmethanes was obtained. USY zeolites show a higherpara-directing selectivity than AICl3. Benzaldehyde reacted with benzene derivatives to afford mixtures of diaryland triarylmethanes. Formation of ditolyl- and dianisylmethanes in the corresponding reactions indicated that bulky triarylmethanes, once formed inside the crystalline framework, have strong diffusional limitations to get out of the zeolite cavities and can undergo subsequent protolytic cleavage. A decrease in the activity of the zeolite to catalyze hydride transfer reactions lead to a decrease on the diphenylmethane yield. Finally, diphenylmethane appears as a primary product indicating that a series of consecutive reactions such as the formation of diarylcarbinols followed by protonation, water elimination, and hydride abstraction are taking place inside the pores of the zeolite before the real primary product comes out from the zeolite.

The photochemistry of enol esters 1 is dominated by electrocyclic ring opening ( 1b → 3 + 4 ), 1,3-acyl migration ( 1c , d → 6c , d ) and [2 + 2] dimerization ( 1d → 11). Photosensitization with triphenylpyrylium tetrafluoroborate (TPT) enhances formation of oxidation products ( 1b → 5 , 1c , d → 9c , d + 10c , d ), presumably through the intermediacy of radical cations 1b–d + .

The reaction of benzil benzhydrylmonoimine 6a with methyl iodide or dimethyl sulphate as the electrophile affords 4-alkoxy-2-aza-1,3-dienes resulting from an O-alkylation. When benzyl chloride is employed, products of O-alkylation, C-alkylation and cyclization are produced, while with toluene-p-sulphonyl chloride only cyclization to a dihydro-oxazole takes place. Benzil α-phenylethylmonoimine 6b yields only products of C- and/or O-alkylation. In one case, when a large excess of dimethyl sulphate is used, cyclization affords N-methyl-2,3,5-triphenylpyrrole. Irradiation of the O-alkylated compounds (E)- and (Z)-4-methoxy-1,1,3,4-tetraphenyl-2-azabuta-1,3-diene and (E)-4-benzyloxy-1,1,3,4-tetraphenyl-2-azabuta,-1,3-diene in the presence of perchloric acid yields isoquinoline derivatives by a photo-Mannich reaction.

NdNiO3 has been prepared with an orthorhombic perovskite structure by a low temperature and low oxygen pressure method starting from a nickel(III) oxide precursor, β-NiO(OH). The compound LaNiO3 has also been obtained by this method. This chemical-precursor-based synthesis overcomes problems related to the use of high oxygen pressures in the synthesis.

The isoquinolinones 8 undergo acid-induced rearrangement to yield the isomeric 1,1-dihydro-3-aroylisoindoles 9 in good yield. The reaction involves hydrolysis of the CN bond to afford a putative intermediate amino diketone 10. Cyclization within this is controlled by two factors (i) the stability of the CN group in the starting material and product and (ii) the relative reactivity of the two carbonyl groups.

The syntheses of new stable derivatives of β,γ-unsaturated carbonyl compounds such as 2,2-dimethyl-4,4-diphenylbut-3-enal 6 and 3,3-dimethyl-5,5-diphenylpent-4-en-2-one 7 are described. The majority of these derivatives undergo efficient aza-di-π-methane rearrangement on short, acetophenonesensitized, irradiation to afford the corresponding derivatives of the cyclopropane carbonyl compound in good to excellent yield; for example, the photoconversion of the oximino trifluoro acetate of the aldehyde 6 affords 2,2-dimethyl-3,3-diphenylcyclopropane-1-carbonitrile 16 in 80% yield. This is of synthetic value since β,γ-unsaturated nitriles do not undergo the aza-di-π-methane reaction. The study has also indicated some limits to the type of derivative that can be used. Thus with a methyl ketone derivative where the functional group can undergo SET from the triplet 1,1-diphenylvinyl moiety; an alternative fragmentation path can be operative in a novel reaction not seen previously in such systems.

Several optically active 1,2-cyclopropanedicarborylic anhydrides and imides were prepared and their chiroptical spectra studied. Despite the strained bicyclic sekeleton of these compounds, their CD spectra show an unusual solvent dependence. This phenomenon can be explained in terms of the cyclopropane ring contribution to the Cotton effect. A deviation of the sekeleton and the anhydride or imide group from the local C, symmetry, shown by MNDO calculations, causes formation of an inherently chiral chromophore constituted by the three-membered ring and neighboring carbonyls. This kind of chromophore is responsible for the observed strong Cotton effects

Several suhstituted N-nitrosopyrrolidines were prepared and their chiroptical spectra studied. The circular dichroism of monocyclic compounds depends on substituents, solvents, and temperature changes. Some of these N-nitrosamines exhibit bisignate CD curves in the region of n-π * transition. On the contrary, conformationally restrictcd bi- and tricyclic compounds show monosignate Cotton effects, the magnitudes of which are almost solvent independent. Bisignate CD curves result from two half-chair conformers of the pyrrolidine ring being in equilibrium and contributing with the opposite CD signs. The Cotton effect signs can be predicted with our «lowered symmetry» sector rule developcd earlier