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Novel quinolin-6-ylthioacetamides and quinolin-6-ylpropanamides have been prepared. They are linker isomers of quinolin-6-yloxyacetamide fungicides in which the oxygen atom of the O,S-acetal in the original lead structures has been replaced by either a sulfur atom or a methylene bridge. The Newman–Kwart rearrangement proved to be highly useful for the concise synthesis of the quinolin-6-ylthioacetamides from available quinolinol building blocks.

Pre-formed phenyliodonium ylides of cyclic and acyclic β-diketones, β-keto esters and β-diesters were reacted with (dichloroiodo)benzene, resulting in transfer of both chloride ligands onto the ylidic carbon. These two hypervalent iodine(III) compounds exhibit high reactivity towards each other under mild reaction conditions and typically afford the gem-dichloride products in good yield. Upon comparison of these chlorination reactions with those of the analogous diazocarbonyl compounds, reactions of iodonium ylides were unilaterally faster, and often gave the products in higher yield.

An important goal of modern organic chemistry is to develop new catalytic strategies for enantioselective carbon-carbon bond formation that can be used to generate quaternary stereogenic centres. Whereas considerable advances have been achieved by exploiting polar reactivity, radical transformations have been far less successful. This is despite the fact that open-shell intermediates are intrinsically primed for connecting structurally congested carbons, as their reactivity is only marginally affected by steric factors. Here we show how the combination of photoredox and asymmetric organic catalysis enables enantioselective radical conjugate additions to β,β-disubstituted cyclic enones to obtain quaternary carbon stereocentres with high fidelity. Critical to our success was the design of a chiral organic catalyst, containing a redox-active carbazole moiety, that drives the formation of iminium ions and the stereoselective trapping of photochemically generated carbon-centred radicals by means of an electron-relay mechanism. We demonstrate the generality of this organocatalytic radical-trapping strategy with two sets of open-shell intermediates, formed through unrelated light-triggered pathways from readily available substrates and photoredox catalysts--this method represents the application of iminium ion activation (a successful catalytic strategy for enantioselective polar chemistry) within the realm of radical reactivity.

A series of C2 symmetric guanidinium salts are prepared as chiral phase transfer catalysts and applied to the alkylation of a glycinate Schiff′s base and to the epoxidation of some chalcones.

There are significant resources of coal on the planet. It is likely that a lot of this coal will be combusted. A 1 GWe coal power plant operating at 35% electrical efficiency and a capacity factor of 75% produces 6.77 million tonnes of CO2 per annum. A closed cultivation system with a carbon capture efficiency of 80% allows production of 2.69 Mt of micro-algal (volatile solids), in a foot print of 19,200 ha for a tubular photo-bioreactor (PBR) and 34,000 ha for a Flat Plate PBR. An open system (raceway pond) at a carbon capture efficiency of 50% produces 1.68 Mt of micro-algal (volatile solids) and requires a footprint of 52,303 ha. Employing a three stage sequential process (combining dark fermentation, photo fermentation and anaerobic digestion) to produce bio-hydrogen and bio-methane from the micro-algae could potentially generate 35% of the primary energy in the coal in the form of renewable gaseous fuel if a closed system of cultivation is used. This is sufficient to fuel 600,000 cars per annum. In the cultivation of micro-algae, pumping and circulation is a considerable parasitic energy demand. The ratio of energy output (gaseous biofuel) to energy input (pumping and circulation) is less than 1 for all the three cultivation systems assessed, ranging from 0.71 for raceway ponds to 0.05 for a tubular PBR. If coal powered electricity is the source of this parasitic energy then a tubular PBR system produces more CO2 than the CO2 captured by the micro-algae.

A series of aryl- and N-substituted isatin derivatives were converted to the corresponding isatin-3-p-tosylhydrazones, and these were subjected to a Lewis base-catalyzed chlorination reaction that employs the hypervalent chlorinating agent PhICl2. The discovery of p-tosylhydrazones as chlorination precursors has expanded the functional group tolerance of the chlorination reaction to now include carbamates, acetamides, and sulfonates. Additionally, this allowed us to circumvent the use of the diazo group in our chlorination reaction, and offers a new avenue for exploring our two-step deoxygenative dihalogenation reaction. We also disclose the use of PhICl2 for the oxidative chlorination of sulfinates to the corresponding sulfonyl chlorides.

Electron paramagnetic resonance (EPR) spectroscopy is an extremely versatile technique for the characterisation of homogeneous catalysts involving paramagnetic centres. The paramagnetic parent pre-catalyst, the activated catalyst itself or any resulting reactive intermediates, can all be monitored in situ in order to delineate the role of the formal metal oxidation state and the influence of ligand structure on the resulting catalytic activity. In this review of our recent results, we describe how highly reactive, low valent transition metal complexes of formal oxidation states Ni(I), Fe(I) and Cr(I) coordinated by N-heterocyclic carbene (NHC) or phosphine ligands and which are active for a range of cross-coupling reactions or ethylene oligomerisation, have been investigated by EPR. Analysis of the EPR spectra revealed (i) how the influence of the NHC ring size affects the electronic properties of the Ni(I) centre, (ii) how low spin Fe(I) intermediates are catalytically competent on-cycle species in cross-coupling reactions and (iii) how intramolecular structural rearrangements involving Cr(I) centres occur following the addition of a co-catalyst to the reaction medium. These results demonstrate the utility of EPR to probe the structure–reactivity relationships in paramagnetic homogeneous catalysts, providing information not readily accessible by other techniques.

The report of a light-activated catalyst that generates usually inaccessible nickel intermediates provides a general strategy that might allow elusive catalytic reactions to be realized. See Letter p.330 Despite advances in carbon–carbon fragment couplings, the ability to create carbon–oxygen bonds via nickel catalysis has been largely unsuccessful. Here David MacMillan and colleagues show that visible-light-excited photoredox catalysts can provide transient access to Ni(III) species that readily participate in reductive elimination. Using this synergistic merger of photoredox and nickel catalysis, the authors develop a highly efficient and general carbon–oxygen coupling reaction using alcohols and aryl bromides.

A photolytic enantioselective perfluoro alkylation of cyclic indolone derived β-keto esters with alkyl iodides of varying chain length is developed.

The mild method offers significant improvement compared to previous procedures in terms of operational simplicity as well as costs and environmental impact of the reagents used.

A mild and efficient Lewis-base or Lewis-acid-catalyzed chlorination of diazodicarbonyl compounds is described.

Incubation of recombinant elaiophylin thioesterase/cyclase with a synthetic pentaketide analogue of elaiophylin, specifically its N-acetylcysteamine thioester (I), produces a novel 16-membered C2-symmetric macrolide (II).

The synthesis of the tricyclus (VI), which is a useful precursor for the preparation of Lycopodium alkaloids involves a Diels—Alder cycloaddition and the cyclization of amine (V) as the key steps.

The dehydroformylation of aldehydes to generate olefins occurs during the biosynthesis of various sterols, including cholesterol in humans. Here, we implement a synthetic version that features the transfer of a formyl group and hydride from an aldehyde substrate to a strained olefin acceptor. A Rhodium (Xantphos)(benzoate) catalyst activates aldehyde carbon-hydrogen (C–H) bonds with high chemoselectivity to trigger carbon-carbon (C–C) bond cleavage and generate olefins at low loadings (0.3 to 2 mole percent) and temperatures (22° to 80°C). This mild protocol can be applied to various natural products and was used to achieve a three-step synthesis of (+)-yohimbenone. A study of the mechanism reveals that the benzoate counterion acts as a proton shuttle to enable transfer hydroformylation.

The ability to bind CO2 through the formation of low-energy, easily-broken, bonds could prove invaluable in a variety of chemical contexts. For example, weak bonds to CO2 would greatly decrease the cost of the energy-intensive sorbent-regeneration step common to most carbon capture technologies. Furthermore, exploration of this field could lead to the discovery of novel CO2 chemistry. Reduction of complexed carbon dioxide might generate chemical feedstocks for the preparation of value-added products, particularly transportation fuels or fuel precursors. Implementation on a large scale could help to drastically reduce CO2 concentrations in the atmosphere. However, literature examples of weakly bonded complexes of CO2 are relatively few and true coordination complexes to a ‘naked’ CO2 fragment are nearly unheard of. In this review article, a variety of complexes of CO2 featuring diverse binding modes and reactivity will be examined. Topics covered include: (A) inclusion complexes of CO2 in porous materials. (B) Zwitterionic carbamates produced from the reaction of CO2 with polyamines. (C) Carbamate salts produced from reaction of CO2 with two equivalents of an amine. (D) Insertion products of CO2 into acid-base adducts (e.g., metal complexes). (E) Lewis acid–base activated CO2, such as frustrated Lewis pair complexes. (F) Simple base–CO2 adducts, wherein the base–CO2 bond is the only interaction formed. Complexes in the last category are of particular interest, and include imidazol-2-carboxylates (N-heterocyclic carbene adducts of CO2) as well as a few other examples that lie outside NHC chemistry.

3-Diazo-2-oxindoles (I) and (III), synthesized from isatins, are rapidly and chemoselectively dichlorinated with PhICl2 in the presence of pyridine under mild conditions in good to excellent yields.

The corresponding reactions of alkyl substituted cyclopropane analogues of (I) are unsuccessful.

Oxidative decarboxylation of α-amino acids provides the corresponding aldehydes which are converted into tetrahydroquinolines by addition of dopamine via Pictet—Spengler reaction.

Over thirty years ago, James and Young reported the first enantioselective olefin hydroacylation by using rhodium catalysts. This viewpoint highlights the advances in this area, including 4-pentenal cyclisations, medium-ring syntheses, and intermolecular variants.

Tricyclic guanidine model compounds (VI) are prepared in 12 steps from pentanediol (I) using a tethered Biginelli condensation between deprotected (II) and β-keto esters (III) as the key step.

The iodocyclization of allyl and homoallyl guanidines is investigated with respect to formation of cyclized and ring-contracted cyclized products.

We report a protocol for the hydroacylation of vinylphenols with aryl, alkenyl, and alkyl aldehydes to form branched products with high selectivity. This cross-coupling yields α-aryl ketones that can be cyclized to benzofurans, and it enables access to eupomatenoid natural products in four steps or less from eugenol. Excellent reactivity and high levels of regioselectivity for the formation of the branched products were observed. We propose that aldehyde decarbonylation is avoided by the use of an anionic directing group on the alkene and a diphosphine ligand with a small bite angle.

A recently reported neutral donor is used as efficient reagent for metal-free reductive cleavage of different types of amino-substrates under photolytic radical conditions.

In recent times, metal-free chemistry has received significant attention due to its inherent qualities and its potential savings in the costs of (i) reagents and (ii) environmental treatments of residues. In this context, recently developed neutral organic electron-donors have shown an ability to perform challenging reductions that are traditionally the preserve of reactive metals and metal-based complexes, under mild reaction conditions. Hence, this feature article is aimed at describing the evolution of neutral organic super-electron-donors and their rapidly developing applications in electron-transfer reactions.

Based on simple ideas of electron-rich alkenes, exemplified by tetrakis(dimethylamino)ethene, TDAE, and on additional driving force associated with aromatization, families of very powerful neutral organic super-electron-donors (SEDs) have been developed. In the ground state, they carry out metal-free reductions of a range of functional groups. Iodoarenes are reduced either to aryl radicals or, with stronger donors, to aryl anions. Reduction to aryl radicals allows the initiation of very efficient transition-metal-free coupling of haloarenes to arenes. The donors also reduce alkyl halides, arenesulfonamides, triflates, and triflamdes, Weinreb amides, and acyloin derivatives. Under photoactivation at 365 nm, they are even more powerful and reductively cleave aryl chlorides. They reduce unactivated benzenes to the corresponding radical anions and display original selectivities in preferentially reducing benzenes over malonates or cyanoacetates. Additionally, they reductively cleave ArC-X, ArX-C (X = N or O) and ArC-C bonds, provided that the two resulting fragments are somewhat stabilized.

Diazoacetate derivatives react with Ph-ICl2 or Tol-IF2 to afford gem-dichlorinated or gem-difluorinated products in the presence of a Lewis base or Lewis acid, respectively.

A practical, palladium-catalyzed synthesis of aryl fluorides from arylboronic acid derivatives is presented. The reaction is operationally simple and amenable to multigram-scale synthesis. Evaluation of the reaction mechanism suggests a single-electron-transfer pathway, involving a Pd(III) intermediate that has been isolated and characterized.

A proof of concept study was undertaken to determine the suitability of monocarbonyl iodonium ylides (MCIYs) as metallocarbene precursors. Exposing Wittig reagents to iodosylbenzene results in a pseudo-Wittig reaction that generates MCIYs in situ. These ylides are intercepted by transition-metal catalysts to generate metallocarbenes, which then undergo either dimerization or cyclopropanation reactions with a variety of alkenes. Additionally, the reaction between diazoester-derived metallocarbenes and Wittig reagents afforded cross-coupling products, illustrating a new type of olefination reaction for phosphonium ylides.

Hexafluoroisobutylene (HFIB) and hexafluoroisobutylene oxide (HFIBO) are versatile and commercially available partially fluorinated intermediates that can be used to prepare derivatives for photo- and micro-lithography, pharmaceuticals, catalysts, electroluminescent devices, surfactants, and fluoropolymers. Both HFIB and HFIBO undergo a wide range of addition and polymerization reactions. HFIB also undergoes oxidation, reduction, and insertion reactions. HFIB has been studied for its potential as a foam blowing agent, a refrigerant, and a fire suppression agent. This first comprehensive review of HFIB and HFIBO includes both the synthetic preparations and reactions of these materials, which are receiving an increasing amount of research attention in a wide variety of applications and uses.

Anisotropic (nonspherical) metal nanoparticles are of widespread research interest because changing the shape of metals at the nanoscale can provide access to materials with unique optical, electronic, and catalytic properties. The development of seeded growth syntheses has provided researchers unprecedented access to anisotropic metal nanocrystals (particularly, gold, silver, platinum, and palladium nanocrystals) with precisely controlled dimensions and crystallographic features. The mechanisms by which the various reagents present in seeded growth syntheses accomplish shape control, however, have yet to be fully elucidated. Recently, the role halide ions play in controlling metal nanocrystal shape has become a subject of particular interest. There are many ways in which the halide ions may direct the anisotropic growth of metal nanocrystals, including modulating the redox potentials of the metal ions, acting as face-specific capping agents, and/or controlling the extent of silver underpotential depositi...

The modern chemical industry relies heavily on homogeneous and heterogeneous catalysts. Understanding the operational mode, or reactivity, of these catalysts is crucial for improved developments and enhanced performance. As a result, various spectroscopic techniques are inevitably used to characterize and interrogate the mechanistic details of the catalytic cycle. Where paramagnetic centres are involved, ranging from transition metal ions to defects and radicals, EPR spectroscopy is without doubt the technique of choice. In this review we will demonstrate the wealth and breadth of information that can be gleaned from this technique, in the characterization of homogenous and heterogeneous systems of catalytic importance, whilst illustrating the advantages that modern high-field and pulsed EPR methodologies can offer.

The title reaction proceeds in the presence of an optically active diphenylprolinol derived catalyst to afford cyclohexadienes with excellent diastereo- and enantioselectivities.

A novel strategy for the hydroacylation of 1,4- and 1,5-keto alcohols to give different substituted lactones is developed.

The development of functional 1,8-naphthalimide derivatives as DNA targeting, anticancer and cellular imaging agents is a fast growing area and has resulted in several such derivatives entering into clinical trials. This review gives an overview of the many discoveries and the progression of the use of 1,8-naphthalimides as such agents and their applications to date; focusing mainly on mono-, bis-naphthalimide based structures, and their various derivatives (e.g. amines, polyamine conjugates, heterocyclic, oligonucleotide and peptide based, and those based on metal complexes). Their cytotoxicity, mode of action and cell-selectivity are discussed and compared. The rich photophysical properties of the naphthalimides (which are highly dependent on the nature and the substitution pattern of the aryl ring) make them prime candidates as probes as the changes in spectroscopic properties such as absorption, dichroism, and fluorescence can all be used to monitor their binding to biomolecules. This also makes them useful species for monitoring their uptake and location within cells without the use of co-staining. The photochemical properties of the compounds have also been exploited, for example, for photocleavage of nucleic acids and for the destruction of tumour cells.

Attempted oxidative photolytic conversion of tetrathiofulvalenes (I) to planar conjugated systems results in unexpected formation of the novel heterocyclic system (II).

Any old iron? Iron catalysts based on the widely available diphosphine ligand bis(diphenylphosphino)ethane have not previously fared particularly well in iron-catalyzed cross-coupling processes. However, this turns out not to be due to any inherently poor performance associated with the ligand, but rather the need to form a bis-chelate complex, either before or during the formation of an active FeI species.

Boronic acids (III) are synthesized by Grignard reaction of aminoborane (I), whereas boronic acids (V) are synthesized by reaction of (I) with in situ formed Grignard reagents (Barbier conditions).

The synthesis of well-defined inorganic nanoparticles in colloidal solution, which evolved gradually from the 1950s onward, has now reached the point where applications in both the research world and the wider world can be realized. This Perspective explores some of the successes and still-remaining challenges in nanoparticle synthesis and ligand analysis, highlights selected work in the areas of biomedicine and energy conversion that are enabled by colloidal nanomaterials, and discusses technical barriers that need to be overcome by chemists and other scientists in order for nanotechnology to achieve its promise.

In the past decade, a host of exceptionally strong organic electron donors has been designed and prepared; their redox potentials are more negative than any previous neutral organic donors and extend beyond E1/2 = −1 V vs. the saturated calomel electrode (SCE). Their ability to reduce a wide range of organic functional groups has been demonstrated and this article provides an overview of the main advances in the area and the guiding principles for the design of these reagents.

Self-assembled monolayers (SAMs) of alkanethiolates on gold can be used to carefully probe immobilized biomolecule interactions with cell-surface receptors. However, due to a lack of experimental throughput associated with labor-intensive production, specialized fabrication apparatus, and other practical challenges, alkanethiolate SAMs have not had widespread use by biological researchers. In this Minireview, we investigate a range of techniques that could enhance the throughput of SAM-based approaches by patterning substrates with arrays of different conditions. Here we highlight microfluidic, photochemical, localized removal, and backfilling techniques to locally pattern SAM substrates with biomolecules and also describe how these approaches have been applied in SAM-based screening systems. Furthermore we provide perspectives on several crucial barriers that need to be overcome to enable widespread use of SAM chemistry in biological applications.

Key feature of this synthesis is the iodide-induced formation of the highly conjugated ketone (V) from mesylate (IVa).

One of the most prevalent methods of forming radicals involves oxidation of closed-shell organic molecules to radical cations, followed by loss of a proton or other positively charged entity, leaving a radical. There are so many ways to trigger the loss of an electron from a neutral molecule to form a radical cation that it is not surprising that this approach has very important and widespread synthetic applications. This article examines the oxidation of neutral organic molecules under various conditions: (i) spontaneous electron transfer to a substrate, which happens with highly electron-rich organic molecules acting as electron donors, (ii) by photoelectron transfer from a substrate to an excited state receptor, where the transfer can be either intramolecular or intermolecular, (iii) by reaction with an oxidizing reagent, and (iv) by electrochemical oxidation. By giving examples of all of these, the article aims to give an overview of organic molecules as electron donors. Notable recent developments in organocatalysis are included, featuring oxidation of enamines, as are recent developments of neutral organic super-electron-donors. Keywords: radical cation; oxidation; electron transfer; electron donor; tetrathiafulvalene; TTF; tetraazaalkene; TDAE; redox potential; organocatalysis