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The gold(I)-catalyzed domino-cyclization of 1,6-Diynes with a t-butylcarbonate group in the propargylic position affords α-hydroxycyclohexenones.

A convenient and efficient organocatalytic procedure for the selective cyclization of 1,3-diketones to give aromatic substituted 4 H -chromen-4-ones under mild reaction conditions using N -triflyl phosphoramide is described. Application of the described conditions is presented in a formal synthesis of ( S )-flavanone.

Push-pull molecules represent a unique and fascinating class of organic π-conjugated materials. Herein, we provide a summary of their recent extraordinary design inspired by letters of the alphabet, especially focusing on H-, L-, T-, V-, X-, and Y-shaped molecules. Representative structures from each class were presented and their fundamental properties and prospective applications were discussed. In particular, emphasis is given to molecules recently prepared in our laboratory with T-, X-, and Y-shaped arrangements based on indan-1,3-dione, benzene, pyridine, pyrazine, imidazole, and triphenylamine. These push-pull molecules turned out to be very efficient charge-transfer chromophores with tunable properties suitable for second-order nonlinear optics, two-photon absorption, reversible pH-induced and photochromic switching, photocatalysis, and intercalation.

The first total synthesis of the neuroactive indole alkaloid (±)-alstoscholarisine A is reported. The key step of the concise synthesis is an efficient domino sequence that was used to assemble the 2,8-diazabicyclo[3.3.1]nonane core through the formation of two C−N bonds and one C−C bond in a single step.

Benzoxadiazocinone derivatives (IV) are synthesized in three steps starting from amines (I) by two alternative routes.

Triazolinediones (TADs) are unique reagents in organic synthesis that have also found wide applications in different research disciplines, in spite of their somewhat “exotic” reputation. In this review, we offer two case studies that demonstrate the possibilities of these versatile and reliable synthetic tools, namely, in the field of polymer science as well as in more recently emerging applications in the field of click chemistry. As the general use of triazolinediones has always been hampered by the limited commercial and synthetic availability of such reagents, we also offer a review of the available TAD reagents, together with a detailed discussion of their synthesis and reactivity. This review thus aims to serve as a practical guide for researchers that are interested in exploiting and further developing the exceptional click-like reactivity of triazolinediones in various applications.

Thermal decomposition of BaFeO4 in static air and nitrogen atmosphere is monitored by thermal analysis, Moessbauer spectroscopy, powder XRD, and electron-microscopic methods.

Domino reactions of ketones with molecular oxygen in the presence of potassium hydroxide and potassium t-butoxide afford cyclic hydroperoxy acetals (3,5-dihydroxy-1,2-dioxanes). Mixed endoperoxides can also be obtained in a three-component reaction of two ketones and oxygen.

The enantioselective hydrosilylation of a broad range of aryl ketones succeeds using a stable and inexpensive zinc salt together with easily accessible chiral diamine ligands.

Most covalent adaptable networks give highly interesting properties for material processing such as reshaping, recycling and repairing. Classical thermally reversible chemical cross-links allow for a heat-triggered switch between materials that behave as insoluble cured resins, and liquid thermoplastic materials, through a fully reversible sol–gel transition. In 2011, a new class of materials, coined vitrimers, was introduced, which extended the realm of adaptable organic polymer networks. Such materials have the remarkable property that they can be thermally processed in a liquid state without losing network integrity. This feature renders the materials processable like vitreous glass, not requiring precise temperature control. In this mini-review, an overview of the state-of-the-art in the quickly emerging field of vitrimer materials is presented. With a main focus on the chemical origins of their unique thermal behavior, the existing chemical systems and their properties will be discussed. Furthermore, future prospects and challenges in this important research field are highlighted.

The synthesis, stability, and toxicity of engineered metal nanoparticles (ENPs) have been extensively studied during the past two decades. In contrast, research on the formation, fate, and ecological effects of naturally-occurring nanoparticles (NNPs) has become a focus of attention only recently. The natural existence of metal nanoparticles and their oxides/sulfides in waters, wastewaters, ore deposits, mining regions, and hydrothermal vents, as exemplified by the formation of nanoparticles containing silver and gold (AgNPs and AuNPs), Fe, Mn, pyrite (FeS2), Ag2S, CuS, CdS, and ZnS, is dictated largely by environmental conditions (temperature, pH, oxic/anoxic, light, and concentration and characteristics of natural organic matter (NOM)). Examples include the formation of nanoparticles containing pyrite, Cu and Zn-containing pyrite, and iron in hydrothermal vent black smoker emissions. Metal sulfide nanoparticles can be formed directly from their precursor ions or indirectly by sulfide ion-assisted transformation of the corresponding metal oxides under anaerobic conditions. This tutorial focuses on the formation mechanisms, fate, and toxicity of natural metal nanoparticles. Natural waters containing Ag(I) and Au(III) ions in the presence of NOM generate AgNPs and AuNPs under thermal, non-thermal, and photochemical conditions. These processes are significantly accelerated by existing redox species of iron (Fe(II)/Fe(III)). NOM, metal–NOM complexes, and reactive oxygen species (ROS) such as O2˙−, ˙OH, and H2O2 are largely responsible for the natural occurrence of nanoparticles. AgNPs and AuNPs emanating from Ag(I)/Au(III)–NOM reactions are stable for several months, thus indicating their potential to be transported over long distances from their point of origin. However, endogenous cations present in natural waters can destabilize the nanoparticles, with divalent cations (e.g., Ca2+, Mg2+) being more influential than their monovalent equivalents (e.g., Na+, K+). The toxicity of NNPs may differ from that of ENPs because of differences in the coatings on the nanoparticle surfaces. An example of this phenomenon is presented and is briefly discussed.

γ-Aminoketones are obtained by direct coupling of cyclic ketones with imines using DABCO as both a base and an electron transfer agent.

New β-amino-δ-chloro carboximidates bearing a chiral sulfoxide auxiliary are prepared and used as building blocks for the synthesis of enantio- and diastereomeric pure 2,3-disubstituted piperidines (similar reactions based on the minor diastereomer are not shown).

An operationally simple and mild protocol is developed for the conversion of a wide range of carboxylic acids into fluoroalkanes.

β-Anomeric derivatives react in a similar way with retention of configuration and E-selectivity in similar yields.

An operationally simple and efficient method for the synthesis of 2-alkynyl-3,3-dichloropyrrolidines from imines and readily available acetylenes is developed using indium(III) triflate as a Lewis acid catalyst.

The asymmetric catalytic alkylation of ortho-substituted benzaldehydes proceeds under Lewis basic and acidic catalyst conditions to give homoallylic alcohols.

The synthetic natural product analogue title compound (I) shows antibacterial activity against methicillin-resistant Staphylococcus aureus strains comparable to the natural product atrop-abyssomicin C, but its cytotoxicity (HeLa and peripheral blood mononuclear cells) is three orders of magnitude lower.

The enantioselective allylation of aldehydes (I) and (VIII) with pinacolborane (II) in the presence of a chiral BINOL-phosphoric-acid-derived catalyst is the key step in the synthesis of the flubofen metabolite (VII) and dapoxetine (X).

The synthesized chloroisothreonine derivatives [(III) and (VII)] are further converted to aziridines (IV) and biologically relevant oxazolidinones (V).

Starting from essential α-amino acids, four new benzo[ d ]imidazole and alkyl-chain-substituted primary amines were synthesized. The reaction sequence involves activation of the Boc-amino acid carboxylic acid, reaction with o -phenylenediamine, and subsequent cyclization to benzo[ d ]imidazole. N-Methylation and final Boc group removal afforded four new primary amines. The synthesized amines were preliminarily applied as organocatalysts in an asymmetric version of the aldol reaction between 4-nitrobenzaldehyde and acetone/cyclohexanone, achieving chemical yields of 40–64% and ee and de values up to 65 and 96%, respectively.

The reaction proceeds via photoinduced single electron transfers (SET) of the aryl ketones and enamines generated from the cyclic ketones and azepane followed by radical—radical coupling.

High pressures extending up to several thousands of atmospheres provide extreme conditions for biological organisms to survive. Recent studies are investigating the survival mechanisms and biological function of microorganisms under natural and laboratory conditions extending into the GigaPascal range, with applications to understanding the Earth's deep biosphere and food technology. High pressure has also emerged as a useful tool and physical parameter for probing changes in the structure and functional properties of biologically important macromolecules and polymers encountered in soft matter science. Here we highlight some areas of current interest in high pressure biophysics and physical chemistry that are emerging at the frontier of this cross-disciplinary field.

All living systems are comprised of four fundamental classes of macromolecules – nucleic acids, proteins, lipids, and carbohydrates (glycans). Glycans play a unique role of joining three principal hierarchical levels of the living world: (1) the molecular level (pathogenic agents and vaccine recognition by the immune system, metabolic pathways involving saccharides that provide cells with energy, and energy accumulation via photosynthesis); (2) the nanoscale level (cell membrane mechanics, structural support of biomolecules, and the glycosylation of macromolecules); (3) the microscale and macroscale levels (polymeric materials, such as cellulose, starch, glycogen, and biomass). NMR spectroscopy is the most powerful research approach for getting insight into the solution structure and function of carbohydrates at all hierarchical levels, from monosaccharides to oligo- and polysaccharides. Recent progress in computational procedures has opened up novel opportunities to reveal the structural information available in the NMR spectra of saccharides and to advance our understanding of the corresponding biochemical processes. The ability to predict the molecular geometry and NMR parameters is crucial for the elucidation of carbohydrate structures. In the present paper, we review the major NMR spectrum simulation techniques with regard to chemical shifts, coupling constants, relaxation rates and nuclear Overhauser effect prediction applied to the three levels of glycomics. Outstanding development in the related fields of genomics and proteomics has clearly shown that it is the advancement of research tools (automated spectrum analysis, structure elucidation, synthesis, sequencing and amplification) that drives the large challenges in modern science. Combining NMR spectroscopy and the computational analysis of structural information encoded in the NMR spectra reveals a way to the automated elucidation of the structure of carbohydrates.

Application of this method is demonstrated in total syntheses of romazarit (XII) and aleglitazar (XIII).

Research on and development of inorganic–organic nanohybrids and nanocomposite materials has attracted increasing attention in recent years. Synthetic strategies for such materials vary from grafting or co-condensation of Si and C sources to the impregnation of silica with polymers. Nanohybrids, prepared using organosilanes, and nanocomposites, obtained by hard or soft templated synthesis, are discussed. Various strategies will be presented that demonstrate how additional carbon properties can be exploited maximising the activity, selectivity and stability of composite materials as solid catalysts. Composite materials allow for the extensive engineering of a catalyst enabling careful tuning of the type, amount and position of active sites, as well as the porosity and hydrophilic nature of the final catalyst. These materials not only combine the advantages of silica (e.g. thermal stability, rigidity, ordering) and carbon (e.g. flexibility, ductility) but also allow their synergetic action in various catalytic applications.

Three-component reaction of N-benzylbenzimidazole (I), α-bromoacetophenones and carbonyl-activated alkynes gives pyrrolobenzimidazoles (IV) in refluxing 1,2-epoxybutane.

Single crystals of CeRu0.5Ni0.5Al are prepared from the elements in a molten Ce0.78Ni0.22 flux (1000 °C for 12 h and 850 °C for 48 h).

Reaction of N-tert-butanesulfinyl α-halo imines with alkoxides afforded new N-tert-butanesulfinyl 2-amino acetals in good to excellent yield. These N-tert-butanesulfinyl 2-amino acetals are convenient precursors for the TMSOTf-promoted synthesis of the corresponding N-protected α-amino aldehydes and ketones, as well as for the HCl-promoted synthesis of 2-amino acetal hydrochlorides and α-amino ketone and α-amino aldehyde hydrochlorides in high yield. Via this method, an asymmetric synthesis of (S)-cathinone hydrochloride (er 94:6) was achieved.

Zincated 3-chloro-3-methyl-1-azaallylic anions undergo a stereoselective aldol addition across aromatic aldehydes and subsequent mesylation to produce syn α-chloro-β-mesyloxyketimines, which were isolated in 80–84% yield and high diastereomeric excess (dr > 97/3) after purification via flash chromatography. The syn α-chloro-β-mesyloxyketimines were further stereoselectively reduced to give stereochemically defined 3-aminopropyl mesylates, which were cyclized to 1,2,3,4-tetrasubstituted 3-chloroazetidines containing three contiguous stereogenic centers. DFT calculations on the key aldol addition revealed the presence of a highly ordered bimetallic six-membered twist-boat-like transition state structure with a tetra-coordinated metal cyclic structure. DFT calculations revealed that chelation of both zinc and lithium cations in the transition state structure leads to the experimentally observed high syn diastereoselectivity of aldol reactions.

Heterogeneous copper catalyzed azide–alkyne click chemistry (CuAAc) has been a quickly emerging research field during the last couple of years as it shows many advantages in comparison to its homogeneous counterpart. In this Minireview, an overview of the state-of-the-art is presented for the first time. For the sake of completeness, not only successful heterogeneous supports but also systems that particularly failed will be discussed. Furthermore, the future prospects and challenges with regard to the application of heterogeneous CuAAC are highlighted.

Neutral anion receptors working in highly demanding solvents are new materials being sought. Benzopyrroles are more acidic than amides and pyrrole itself, and are promis- ing building blocks in the design of host compounds. A whole series of receptors based upon benzopyrroles were synthesized and evaluated. They include carbazole, dipyrrolonaph - thalene, and 7-aminoindole-based hosts. Most of them demonstrate moderate binding affini- ties in dimethyl sulfoxide (DMSO) and have good selectivity toward tetrahedral oxyanions. Recently, a group of receptors utilizing 7-aminoindole and urea moieties proved to work in a very competitive solvent—methanol.

This short review aims to summarize recent advances in the use of transition-metal-catalyzed and -mediated methodology for the synthesis of steroid and steroid-like skeletons reported in the last decade. The methodologies used include transition-metal-catalyzed or -mediated [2+2+2] and other cycloadditions, the Pauson–Khand reaction, cross-coupling and Heck reactions, processes based on the activation of single and multiple bonds, metathesis reactions, hydrovinylation, and other reactions. Several examples of total synthesesof steroid compounds [e.g., (+)- and (–)-estrone, desogestrel] by these procedures are presented.

The title reaction proceeds with good to high enantioselectivity but low diastereoselectivity.

The complementary Watson-Crick base-pairs, A:T and G:C, have long been recognized as pivotal to both the stability of the DNA double helix and replication/transcription. Recently, the replacement of the Watson-Crick base-pairs with other molecular entities has received considerable attention. In this tutorial review we highlight different approaches used to replace natural base-pairs and equip them with novel function. We also discuss the advantages that non-natural base-pairs convey with respect to practical applications.