The direct conversion of methane to methanol at low temperatures was achieved selectively using dioxiranes 1a,b either in the isolated form or generated in situ from aqueous potassium caroate and the parent ketone at a pH close to neutrality. Results suggest that the more powerful dioxirane TFDO (1b) should be the oxidant of choice. The

A synthesis of representative monohydroxy derivatives of valinomycin (VLM) was achieved under mild conditions by direct hydroxylation at the side chains of the macrocyclic substrate using dioxiranes. Results demonstrate that the powerful methyl(trifluoromethyl)dioxirane 1b should be the reagent of choice to carry out these key transformations. Thus, a mixture of compounds derived from the direct dioxirane attack at the β-(CH3)2CH alkyl chain of one Hyi residue (compound 3a) or of one Val moiety (compounds 3b and 3c) could be obtained. Following convenient mixture separation, each of the new oxyfunctionalized macrocycles became completely characterized.

Described here is the first application of plasma-enhanced chemical vapor deposition (PECVD) to the synthesis of catalitically active materials, prepared by covering Merrifield resin beads with an oxygen-containing fluorocarbon thin film deposited in a hexafluoropropene-O2 plasma. Such modified resins catalyze both the selective epoxidation of trans--methylstyrene and its double oxidative cleavage to benzaldeyde in organic–water biphasic media at room temperature, using potassium monoperoxysulfate (KHSO5) as the terminal oxidant. Interestingly, the epoxide/benzaldehyde product ratio strictly depends on the conditions adopted for catalyst generation. This, coupled with evidence for the presence of carbonyl groups on the surface of treated resins, point to dioxirane- and singlet oxygen (1O2)-mediated oxidations; 1O2 being produced in the decomposition of KHSO5. Compared to traditional synthetic procedures to obtain similar catalytic active materials, the application of PECVD is eco-sustainable and inexpensive. Also, the activity of catalysts can be fully restored upon iterative re-treatment of the exhausted resin

We have synthesized 1-aza-adamantan-4-one (C9H13NO) starting from commercial 1,4-cyclohexanedio nemonoethylene acetal and tosylmethylisocianide, following a procedure already described in the liter-ature. The high degree of sample purity was demonstrated by gas chromatography and mass spectromet-ric measurements and its structure evidenced by 1H and 13C NMR spectroscopy. Among numerous interests in physical chemistry, this target molecule is of high relevance for mechanistic evaluation and the synthesis of novel pharmaceutical compounds. We present a thorough spectroscopic study of this molecule by gas phase vibrational and rotational spectroscopy. Accurate vibrational frequencies have been determined from infrared and far-infrared spectra. The pure rotational spectrum of the molecule has been recorded both by cavity-based Fourier transform microwave spectroscopy in the 2–20 GHz region by supersonically expanding the vapor pressure of the warm sample and by room-temperature absorption spectroscopy in the 140–220 GHz range. Accurate sets of rotational and centrifugal distortion parameters of 1-aza-adamantan-4-one in its ground state and in five vibrationally excited states have been derived from these measurements and compared to accurate quantum chemical calculations. The hyperfine parameters have been discussed in terms of molecular structure around the nitrogen quadru-pole nucleus.

With use ofmethyl(trifluoromethyl)dioxirane (TFDO), the oxidation of some tripeptide esters protected at the N-terminus with carbamate or amide groups could be achieved efficiently under mild conditions with no loss of configuration at the chiral centers. Expanding on preliminary investigations, it is found that, while peptides protected with amide groups (PG=Ac-, Tfa-, Piv-) undergo exclusive hydroxylation at the side chain, their analogues bearing a carbamate group (PG=Cbz-, Moc-, Boc-, TcBoc-) give competitive and/or concurrent hydroxylation at the terminalN-Hmoiety. Valuable nitro derivatives are also formed as a result of oxidative deprotection of the carbamate group with excess dioxirane. A rationale is proposed to explain the dependence of the selectivity upon the nature of the protecting group.

A remarkable example of the progress in metal-free oxidation is the development of oxidation with dioxiranes. The reactivity of these peroxides seems to be due to the tendency for easy electrophilic O-atom transfer to nucleophilic substrates. This has been applied in order to achieve high regio- and stereoselective epoxidation and oxyfunctionalizations of target molecules. This review addresses a new approach consisting of the application of homogeneous and heterogeneous dioxiranes isolated and generate in situ. This method has shown promise to contribute to resolving a well-recognized general problem in the organic synthesis to achieve efficient synthetic methods that take into account the fundamental principles of green chemistry.

A new hybrid material (3) consisting of trifluoromethyl ketone (TFMK) moieties, immobilized on silica through an appropriate spacer, was synthesized and characterized. Lacking easily oxidizable functionalities in the spacer chain, this material proved to be an excellent catalyst in heterogeneous epoxidations with potassium caroate (KHSO5), surpassing other reported catalysts in performance and stability. The efficiency of silica-supported catalyst 3 could be assessed upon carrying out the selective dioxirane-mediated epoxidation of representative alkenes in high yields. The solid catalyst could then be recovered and reused in a number of consecutive oxidation cycles.

This work addresses a new approach developed in our laboratory, consisting in the application of isolated dimethyldioxirane (DDO, 1a) labelled with 18O for synthesis of epoxidized glyceryl linoleate (Gly-LLL, 2). We expect that this work could contribute in improving analytical methods for the determination of epoxidized soybean oil (ESBO) in complex food matrices by adopting an 18O-labelled-epoxidized triacylglycerol as an internal standard.

Cardanol is a natural and renewable organic raw material obtained as the major chemical component by vacuum distillation of cashew nut shell liquid. In this work a new sustainable procedure for producing cardanol-based micellar nanodispersions having an embedded lipophilic porphyrin itself peripherally functionalized with cardanol substituents (porphyrin-cardanol hybrid) has been described for the first time. In particular, cardanol acts as the solvent of the cardanol hybrid porphyrin and cholesterol as well as being the main component of the nanodispersions. In this way a “green” micellar nanodispersion, in which a high percentage of the micellar system is derived from renewable “functional” molecules, has been produced.

Low pressure plasma was used for preparing heterogeneous organocatalysts 2-(A)-(C) suitable for dioxirane-mediated epoxidations. Heterogenization was accomplished by adsorption of the methyl perfluoroheptyl ketone (2) on fluorinated supports (A)-(C) deriving from the treatment of commercial C₈-silica gel in low pressure plasma fed with fluorocarbons. Catalyst 2-(C) proved to be the most efficient one, promoting epoxidation of an array of alkenes, including unsaturated fatty esters like methyl oleate (10) and the triglyceride soybean oil (11), with the cheap potassium peroxymonosulfate KHSO₅ (caroate) as a green oxidant. Notably, the perfluorinated matrix gives rise to the activation of caroate, generating singlet oxygen. Materials were characterized by infrared Attenuated Total Reflectance spectroscopy (ATR-FTIR), X-ray Photoelectron Spectroscopy (XPS ) and Emission Scanning Electron Microscope (FESEM).

The adulteration of extra virgin olive oil (EVOO) with hazelnut oil (HO) is frequent and constitutes a seri- ous concern both for oil suppliers and consumers. The high degree of similarity between the two oils as regards triacylglycerol, total sterol and fatty acid profile, complicates the detection of low percentages of HO in EVOO. However, phospholipids (PLs) are usually present in seed oils at a concentration range of 10– 20 g/kg, while the amounts of PLs in VOOs are 300–400 times lower. Thus, in this work a sample pretreat- ment procedure focused towards the selective PLs extraction was developed; the Bligh–Dyer extraction procedure was modified introducing the ionic liquid resulting from the combination of TBA (tributyl- amine) and CHCA (a-Cyano-4-hydroxycinnamic acid) as extraction solvent. The selective extraction and enrichment of phospholipids from EVOO and HO samples was then achieved. The relevant extracts were analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI- TOF-MS) using the same ionic liquid TBA-CHCA as MALDI matrix, that was found to be very suitable for PLs analysis. In fact, a remarkable increase of the phospholipids signals, with a simultaneous decrease of those relevant to triacylglycerols and diacylglycerols, was observed in the relevant mass spectra. The applicability of the whole method to the individuation of the presence of HO in EVOO was demonstrated by the analysis of EVOO samples progressively adulterated with variable quantities of HO, that was still detectable at a 1% contamination level.

Bio-polyols synthesized from vegetables oils are a great alternative to petrochemical polyols for polyurethanes industry. The simplest approach to bio-polyols synthesis involves epoxidation of carbon –carbon double bond of unsaturated fatty ester moieties and subsequent epoxide ring-opening by nucleophilic reagents. In order to improve the latter process by increasing both productivity and product quality, the advantages of flow chemistry were exploited, such as facile automation, reproducibility, improved safety and process reliability, investigating for the first time in the literature the methanolysis reaction of epoxidized soybean oil (ESO) in a continuous flow mode. Compared with batch reaction, flow mode allowed the cut of the reaction time from 30 min to 2 min, and the reduction of catalyst concentration by an order of magnitude, which brought significant benefits in terms of cost efficiency and eco-sustainability, rendering the method suitable for industrial applications

An oxidative route to N-substituted sulfonamidic azobenzene derivatives is reported. A mechanism, based on a rationalization of previous findings, is proposed. This simple one-pot method could be adapted to the synthesis of a range of substituted sulfonylazobenzenes with potential applications in the pharmaceutical and industrial fields

By taking advantage of the appreciable stability of dioxiranes in water, a safe yet efficient route to ω-nitro acids by oxidation of lactams of various ring size under mild conditions has been reported. In essentially all the cases examined, reactions proceed selectively to afford products in remarkable high yields (up to 99%) and with high purity (94-99%). Also, an interesting example of higher reaction selectivity in water than in organic solvent (acetonitrile) is discussed.

Dioxiranes are used as reagents in a myriad of synthetically useful oxidations performed in aqueous medium. To extend such an approach also to substrates that are highly hydrophobic, we propose here the use of microemulsions based on the surfactant hexadecyltrimethylammonium hydrogen sulphate (CTAHS) because of its high stability against peroxide species. In this paper, we examine the dioxirane (isolated or generated in situ) reactivity in different CTAHS microemulsions. Yield and selectivity of the oxidation of -methylstyrene (2) by dimethyldioxirane (DDO, 1a) generate “in situ” and of laurolactam (3) by isolated methyl(trifluorometyl)dioxirane (TFDO, 1b) were studied. For each microemulsion, the aggregate size and the localization of the components were determined by a combination of NMR and light scattering techniques. The hydrodynamic radius of the micelles is close to the length of the surfactant and this suggests they are spherical in shape. When acetone (the precursor of 1a) is present in the formulation, it partitions itself between the aqueous bulk and the micellar palisade so that the dioxirane eventually formed is readily available to oxidize substrates secluded in the micelle. Apolar substrates, confined within the micelles, are protected from uncontrolled oxidations, leading to an astonishing high selectivity of oxidation of laurolactam (3) to 12-nitro-lauric acid (3a) by TFDO (1b). This opens the way to an easy and green procedure (performed in water under mild conditions) to synthetize omega-nitroacids.

Composite materials prepared by loading polycrystalline TiO2 powders with lipophilic highly branched Cu(II)- and metal-free phthalocyanines or porphyrins, which have been used in the past as photocatalysts for photodegradative processes, have been successfully tested for the efficient photoreduction of carbon dioxide in aqueous suspension affording significant amounts of formic acid. The results indicated that the presence of the sensitizers is beneficial for the photoactivity, confirming the important role of Cu(II) co-ordinated in the middle of the macrocycles. A comparison between Cu(II) phthalocyanines and Cu(II) porphyrins indicated that the Cu(II)- phthalocyanine sensitizer was more efficient in the photoreduction of CO2 to formic acid, probably due to its favorable reduction potential.

The reaction of 1,3-dimethylimidazolium-2-carboxylate and dimethylcarbonate (DMC) at high temperature yielded the new compounds 2-ethyl-1,3-dimethylimidazolium methyl carbonate salt and 2-ethyl-1,3-dimethylimidazolium-4-carboxylate zwitterion which were obtained as a mixture in approximately 4:1 molar ratio. The compounds were also isolated in pure form through alternative synthetic procedures and characterized by ESI-HRMS, 1H, 13C NMR and FTIR spectroscopy. The 1,3-dimethylimidazolium-2-carboxylate/dimethylcarbonate system was employed in the synthesis of 1,7-heptanedioic acid dimethyl ester from cyclohexanone and DMC. The target compound was obtained in 49% yield and 66% selectivity.

Valinomycin (VLM, 1) is a K+ ionophore cyclodepsipeptide capable of depolarizing mitochondria and inducing apoptosis to several mammalian cell types, including a number of tumor cell lines. With the aim of creating VLM-based ligand-targeted anticancer drugs that may selectively convey VLM to pathological cells, we have previously introduced derivatizable hydroxyl handles into the VLM structure, allowing to access a three-entity library of monohydroxyl VLMs (HyVLMs) bearing the OH group at the isopropyl side chain of a d-Hyi, d-Val, or l-Val residue (analogs 2-4, respectively). Herein, the levels of bioactivity retained by the conjugable HyVLMs have been assessed on the basis of their ability to alter the functionality of isolated rat-liver mitochondria. Experiments run with HyVLMs in the range 1-10nM and in 20 or 125mM KCl medium show that the hydroxyl group reduces the potency of HyVLMs relative to VLM to an extent that depends upon the molecular site involved in the hydroxylation. On the other hand, estimation of the stability constants of complexes (in methanol at 25 degrees C) of each analog with Na+, K+, and Cs+ reveals that HyVLMs nicely retain the VLM binding features, except for a moderate increase in the stability of Na+ complexes. These findings, along with pertinent structural considerations, suggest that the incorporation of OH into the VLM structure might actually have altered its K+ transporting ability across mitochondrial membranes. Besides facing new aspects of VLM structure-activity relationship, these studies set the basis for the rational design of ligand-HyVLMs conjugates through derivatization of hanging OH group. Copyright (c) 2013 European Peptide Society and John Wiley & Sons, Ltd.

Epoxides are essential building blocks in organic chemistry. The epoxidation of unsubstituted cyclic dienes 2, 3, 4 and triene 5 using dimethyldioxirane (1a) and its trifluoro analog 1b methyl(trifluoromethyl)dioxirane has been investigated. The excellent yields obtained (90-98%) are accompanied by outstandingly high diastereoselectivities (90-98%). Interpretation of results based upon the early idea that polar groups can direct the dioxirane attack by dipole-dipole interaction provides a likely rationale, along with a more generalized mechanistic view

In this article the environmentally friendly preparation of “green nanocarriers” based on the combination of natural renewable materials is described. Cardanol (CA), obtained as the major by-product of the cashew industry, and cholesterol (CH) have been used to encapsulate chlorogenic acids (CQAs), a class of natural phenolic compounds, extracted from two different rowanberries (Sorbus Americana and Vaccinium sp.). The chlorogenic acid extracts and cardanol-based vesicular nanodispersions have been characterized respectively by ultra high performance liquid chromatography (UHPLC) and transmission electron microscopy (TEM) and dynamic light scattering (DLS).

Organic functionalization of carbon nanotube sidewalls is a tool of primary importance in material science and nanotechnology, equally from a fundamental and an applicative point of view. In this paper, a mild and easily tunable approach to the sidewall decoration of single-walled carbon nanotubes (SWCNTs) with epoxides and their subsequent derivatization (ring opening) upon treatment with reactive nucleophiles is presented. The treatment of HiPco purified SWCNTs with dioxirane solutions results in highly oxidized CNTs, which are used as electrophilic platforms for their successive derivatization/functionalization. As a result of the choice of accessible, easy to handle and store dioxiranes, multiple oxidation cycles could be performed on the same sample, thus allowing for a final improvement in the extent of oxidation at the CNT sidewall.

Metal-free, Cu(II)- or Zn(II) tetrakis [4-(2,4-bis-(1,1-dimethylpropyl)phenoxy)]phthalocyanines loaded over TiO2 (anatase) proved to be active in the photoreduction of CO2 to formic acid (HCO2H) in water under UV-vis light. CuPc/TiO2 is catalyst of choice, allowing to reach a maximum yield of HCO2H, unequalled by any other similar catalytic systems. Because of their low environmental impact, low potential cost, and efficient power conversion, these multipurpose materials show promise in the setup of sustainable methods for CO2 valorization. (C) 2014 Elsevier B.V. All rights reserved