Enantioselective vinylogous aldol reaction of Chan’s diene catalyzed by hydrogen-bonding

Hydrogen-bonding activation of aromatic aldehydes by a TADDOL-derivative promotes the vinylogous aldol reaction of Chan’s diene in moderate efficiency and enantioselectivity. Electron-poor aromatic aldehydes show an enhanced reactivity and a competing asymmetric hetero-Diels-Alder reaction takes place in comparable (or higher) yields and enantiomeric excesses.     

Quantitative Label-Free Comparison of the Metabolic Protein Fraction in Old and Modern Italian Wheat Genotypes by a Shotgun Approach

Wheat represents one of the most important cereals for mankind. However, since wheat proteins are also the causative agent of several adverse reactions, during the last decades, consumers have shown an increasing interest in the old wheat genotypes, which are generally perceived as more “natural” and healthier than the modern ones. Comparison of nutritional value for modern and old wheat genotypes is still controversial, and to evaluate the real impact of these foods on human health comparative experiments involving old and modern genotypes are desirable. The nutritional quality of grain is correlated with its proteomic composition that depends on the interplay between the genetic characteristics of the plant and external factors related to the environment. We report here the label-free shotgun quantitative comparison of the metabolic protein fractions of two old Sicilian landraces (Russello and Timilia) and the modern variety Simeto, from the 2010–2011 and 2011–2012 growing seasons. The overall results show that Timilia presents the major differences with respect to the other two genotypes investigated. These differences may be related to different defense mechanisms and some other peculiar properties of these genotypes. On the other hand, our results confirm previous results leading to the conclusion that with respect to a nutritional value evaluation, there is a substantial equivalence between old and modern wheat genotypes. Data are available via ProteomeXchange with identifier <PXD024204>.     

Bis-furyl alditols via SnCl4- or ZnCl2-catalysed reaction of furans with sugars

Alditols have been obtained in very high yield using an excess of electron-rich furans with respect to the protected sugars. The scope and limitation of the reaction have been explored.     

Relaxometric investigations addressing the determination of intracellular water lifetime: a novel tumour biomarker of general applicability

ABSTRACT

¹H Fast-Field Cycling NMR relaxometry is proposed as a powerful method to investigate tumour cell metabolism by measuring changes in cell water content and mobility across the cellular membrane. Measurements of intracellular water residence time in cultured cells were carried out by measuring T₁ at fixed field (0.2?T) after the addition of a paramagnetic Gd complex (Prohance) at different concentrations in the external medium. Investigations on tumour cells (mammary adenocarcinoma TS/A) grown in normo- or hypoxic conditions or suspended in ‘hypo-osmotic’ solutions allowed us to demonstrate that both hypoxic and hypo-osmotic conditions cause a marked increase in water mobility as assessed by the elongation of T₁. Conversely, the metabolic change caused by glutamine (an aminoacid essential for tumour growth) deprivation caused a water mobility decrease (shorter T₁). These findings suggest that T₁ measurements at low and variable magnetic field strengths, giving access to the assessment of intracellular water lifetime, can provide important information about tumour cell metabolism in real time and non-invasively.     

Vanillin: The Case for Greener Production Driven by Sustainability Megatrend

Approaching the end of the second decade of the 21^st century, almost the whole demand of vanillin is met by the synthetic product obtained either via a petrochemical process starting from phenol and glyoxylic acid or from energy intensive alkaline oxidative depolymerization of lignin. Only a minor fraction is comprised of natural vanillin obtained from ferulic acid fermentation, and even less of highly valued Vanilla planifolia extracts. Are there alternative green production methods? And, if yes, are they suitable to find practical application?     

Cross-linked natural IntegroPectin films from citrus biowaste with intrinsic antimicrobial activity

Cellulose - Pectin recovered via hydrodynamic cavitation (IntegroPectin) from lemon and grapefruit agri-food waste intrinsically containing antimicrobial bioactive substances (flavonoids, phenolic...     

Noncovalent synthesis in aqueous solution and spectroscopic characterization of multi-porphyrin complexes

The interactions of the tetracationic meso-tetrakis(N-methyl-4-pyridyl)porphyrin (H(2)TMPyP) and its metallo derivatives (MTMPyP) (where M=copper(II), zinc(II), and gold(III) with the octa-anionic form (at neutral pH) of 5,11,17,23-tetrasulfonato-25,26,27,28-tetrakis(hydroxycarbonylmethoxy)calix[4]arene (C(4)TsTc) lead to a series of complex species whose stoichiometry and porphyrin sequence can be easily tuned. Crystallographic, spectroscopic, and diffusion NMR studies converge towards a common picture in which a central 1:4 porphyrin/calixarene unit serves as a template for the formation of more complex species. These species arise by successive, stepwise addition of single porphyrin molecules above and below the plane of the 1:4 central core to ultimately give a 7:4 complex. Noticeably, the stoichiometry of the various complex species corresponds to the actual concentration ratio of porphyrins and calixarenes in solution allowing the stoichiometry of these species to be easily tuned. This behavior and the remarkable stability of these species allow homo-porphyrin and hetero-(metallo)porphyrin species to be formed with control of not only the stoichiometry but also the sequence of the porphyrin array. The flexibility and ease of this approach permit, in principle, the design and synthesis of porphyrin arrays for predetermined purposes. For example, we have shown that it is very easy to design and obtain mixed porphyrin species in which a foreseen photoinduced electron-transfer is indeed observed.     

Aerobic oxidation of alcohols in carbon dioxide with silica-supported ionic liquids doped with perruthenate

The replacement of toxic Cr(VI) for O2 and of chlorinated solvents for supercritical carbon dioxide (or ionic liquids) in the oxidation of alcohols remains hindered by the low selectivity and activity of the current heterogeneous catalysts. Using an integrated approach that combines sol-gel entrapped perruthenate as aerobic catalyst, an encapsulated ionic liquid as solubility promoter, and scCO2 as the reaction solvent, we have developed a system capable of rapidly converting different alcohols into carbonyl compounds with complete selectivity, including substrates which are otherwise difficult to oxidise. The methodology is generally applicable and may easily be extended to other waste-free, catalytic syntheses of fine chemicals.     

High-throughput analysis of bergamot essential oil by fast solid-phase microextraction-capillary gas chromatography-flame ionization detection

The advantages of using a narrow-bore column in headspace solid-phase microextraction-gas chromatographic (HS-SPME-GC) analysis are investigated. An automated rapid HS-SPME-GC method for the determination of volatile compounds in a complex sample (bergamot essential oil) was developed. A low-capacity (7 microm) SPME fibre was employed, enabling a short equilibration time (15 min). The absorbed volatile compounds were then separated in 12.5 min on a 10 m x 0.1 mm I.D. capillary. The fast GC method was characterized by relatively moderate GC parameters (head pressure: 173 kPa; temperature program rate: 12 degrees C/min). The employment of the low-capacity fibre also suited the reduced sample capacity of the capillary employed, hence column overloading was avoided. Analytical repeatibility was determined in terms of retention times (maximum RSD: 0.32%) and peak areas (maximum RSD: 9.80%). The results obtained were compared to those derived from a conventional HS-SPME-GC (a 30 microm SPME fibre and 0.25 mm I.D. capillary were used) application on the same sample. In this respect, a great reduction of analytical time was obtained both with regard to the conventional SPME equilibration and GC run times, which both required 50 min. Peak resolution was altogether comparable in both applications. Although a slight loss in terms of sensitivity was observed in the rapid approach (generally within the 25-50% range), this did not impair the detection of all peaks of interest. Finally, the selectivities of the 30 and 7 microm fibres were evaluated and, as expected, these were in good agreement.     

Stereoselective uncatalyzed synthesis of 2,3-unsaturated-4-n-substituted-beta-O-glycosides by means of a new D-galactal-derived N-(mesyl)-aziridine

The reaction of the new D-galactal-derived allylic aziridine 1beta with O-nucleophiles (alcohols and monosaccharides) affords, in a high to complete beta-stereoselectivity, the corresponding 2,3-unsaturated-beta-O-glycosides bearing a beta-N-functionality at C4.