Photochemistry of N-(selenoalkyl)-phthalimides. Formation of N, Se-heterocyclic systems

A variety of N-(selenomethyl)alkyl-phthalimides (alkyl = -(CH2)n-; n = 2-5, 1a, b, d, e) and N-(selenobenzyl)propyl phthalimide (1c) were synthesized and their photochemistry was studied at λ = 300 nm. Steady-state photolysis and laser time-resolved spectroscopy studies confirmed that these reactions proceeded by direct or acetone-sensitized excitation followed by intramolecular electron transfer (ET) between Se atom and the phthalimide moiety. Two main pathways are possible after ET: proton transfer to the ketyl radical anion from the CH3Se+ or the -CH2Se+- moieties, yielding the corresponding biradicals. Collapse of these biradicals yields cyclization products with the respective endo or exo selenium-containing heterocycles. Competition between both proton transfer processes depends on the chain length of the alkyl spacer between the phthalimide and Se groups as well as the size of the cycle being formed.Fil: Oksdath Mansilla, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Heredia, Adrián Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Argüello, Juan Elias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Peñeñory, Alicia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin

Imide and isatin derivatives as β-lactam mimics of β-lactam antibiotics

Activated γ-lactams, which are derivatives of succinimide, phthalimide and isatin with suitable elements of molecular recognition, have been synthesised as mimics of the ß-lactam antibiotics and their chemical and biological reactivity determined

Assessment of irregularities in organic imports from Ukraine to the EU in 2016, notified in OFIS

The underlying study of this report set out to improve the understanding situation concerning residues found in organic food products exported from Ukraine, and to formulate guidelines for identifying and reducing risks for contamination through non-permitted substances based on the results of an in-depth analysis of those residue cases notified in the European Commission’s Organic Farming Information System (OFIS) in 2016. Not surprisingly, the combination of various factors such as (i) the additional sampling required by the new EU import guidelines, (ii) the growing number of exported organic lots from Ukraine, and (iii) the improved analysis technology, led to an increased total number of cases of irregularities notified in OFIS in comparison to previous years. Nevertheless, the number of irregularities in Ukraine in 2016, notified in OFIS, is moderate (affecting estimated < 1% of all exported consignments from Ukraine). Of the lots affected, two thirds were ultimately released as “organic” after additional investigations had been carried out by the respective export CB. Yet, if analysis results of samples taken by the CB’s prior the export, i.e. from crops during the growing season and from lots before they are released for export are included in the risk assessment, Ukraine and its neighbouring countries do need to be considered as relatively high risk countries in terms of contamination and irregularities. It is further interesting to note that the likeliness of residue findings vary a lot among different CBs. The reasons why some CB’s have a high share of residue findings whereas for others proportionally much less residues are found are unclear and should be the subject of further assessments. One assumption is that some CBs took risk-oriented samples whereas others did not. Sampling during the production process (field/leafs and dust) effectively supports organic integrity. Most CB nevertheless focus on residue free final products. The way a CB responds on detected irregularities, i.e. investigates a case and derives “lessons learnt” is very important. A majority of OFIS cases from Ukrainian exports seems to be linked to insufficient management of handling procedure during the storage processes and the transport. However, drift on the field or the intentional use of unauthorised substances are also potential sources of irregularities related to exports from Ukraine. Apart from those cases for which likely root causes have been identified, no clear explanation for discrepancies between lab results between export and import countries could be found for nearly one third of the Ukrainian OFIS cases. Further investigations should be carried out to help identify the reasons for the relatively large differences between the lab results of samples taken from the same trade lots. It is important to better understand these discrepancies in sample measurements because these may lead to significant negative economic impacts for everyone involved in the value chain, even though no rules may have been broken. Another recommendation resulting from this study is to focus more on detecting potential contaminations on the field during the period of crop cultivation. Special attention should be given here to the testing of leaf sample of crops in which contamination has been detected in the past: rapeseeds, sunflower seeds or high quality milling wheat. CB’s should have guidelines on how and when leaf samples should be best taken. Ukrainian organic operators often complain that all Ukrainian operators are put in the same basket and treated as high-risk suppliers. In response to the stricter regulations imposed on them, operators and experts participating in the International Conference “Improving Integrity of Organic Supply Chains” in Odesa 2017 called for an amendment of the inspection policy. Instead of labelling entire countries as high-risk, focus should rather be placed on risky value chains. Supply chains considered high-risk should be relieved from extra measures, once they have demonstrated consistent compliance

SENSING IMMOBILIZED MOLECULES OF STREPTAVIDIN ON A SILICON SURFACE BY MALDI-TOF MASS SPECTROMETRY AND FLUORESCENCE MICROSCOPY

Indexación: Web of Science; Scielo.A hydrogen-terminated Si (111) surface was modified to form an aminoterminated monolayer for immobilization of streptavidin. Cleavage of an N-(ω-undecylenyl)-phthalimide covered surface using hidrazine yields an amino group-modified surface, which serves as a substrate for the attachment of biotin and subsequently streptavidin. We used surface analytical techniques to characterize the surface and to control the course of functionalization before the immobilization of streptavidin. To confirm the presence of the streptavidin Texas red on the surface two powerful techniques available in a standard biochemical laboratory are used, Fluorescence Microscopy and MALDI-TOF that allow us to detect and determine the immobilized streptavidin. This work provides an avenue for the development of devices in which the exquisite binding specificity of biomolecular recognition is directly coupled to a biosensor. In addition, we have demonstrated that MALDI-TOF and fluorescence microscopy are useful techniques for the characterization of silicon functionalized surfaces.http://ref.scielo.org/gm87c

Generation of Molecular Complexity from Cyclooctatetraene: Preparation of Optically Active Protected Aminocycloheptitols and Bicyclo[4.4.1]undecatriene

The racemic (6-cyclo-heptadienyl)Fe(CO)3+ cation ((±)-7), prepared from cyclooctatetraene, was treated with a variety of carbon and heteroatom nucleophiles. Attack took place at the less hindered C1 dienyl carbon and decomplexation of the (cycloheptadiene)Fe(CO)3 complexes gave products rich in functionality for further synthetic manipulation. In particular, a seven-step route was developed from racemic (6-styryl-2,4-cycloheptadien-1-yl)phthalimide ((±)-9 d) to afford the optically active aminocycloheptitols (−)-20 and (+)-20

Synthesis and Reactivity of Tricarbonyl(1-ethoxy-carbonyl-2-methylpentadienyl)iron(1+) Cation

The title cation was prepared in two steps from the known (ethyl 3-methyl-6-oxo-2,4-hexadienoate)Fe(CO)3. Reation of the cation with NaBH3CN, methyl cuprate, phthalimide, water, PPh3, or malonate anions gave predominantly the products from nucleophilic attack at the C5 pentadienyl carbon

Generation of Molecular Complexity from Cyclooctatetraene: Preparation of Aminobicyclo[5.1.0]octitols

A series of eight stereoisomeric N-(tetrahydroxy bicyclo-[5.1.0]oct-2S*-yl)phthalimides were prepared in one to four steps from N-(bicyclo[5.1.0]octa-3,5-dien-2-yl)phthalimide (±)-7, which is readily available from cyclooctatetraene (62 % yield). The structural assignments of the stereoisomers were established by 1H NMR spectral data as well as X-ray crystal structures for certain members. The outcomes of several epoxydiol hydrolyses, particularly ring contraction and enlargement, are of note. The isomeric phthalimides as well as the free amines did not exhibit β-glucosidase inhibitory activity at a concentration of less than 100 μM

Reactivity of (1-methoxycarbonylpentadienyl)iron(1+) cations with hydride, methyl, and nitrogen nucleophiles

The reaction of tricarbonyl and (dicarbonyl)triphenylphosphine (1-methoxycarbonyl-pentadientyl)iron(1+) cations 7 and 8 with methyl lithium, NaBH3CN, or potassium phthalimide affords (pentenediyl)iron complexes 9a-c and 11a-b, while reaction with dimethylcuprate, gave (E,Z-diene)iron complexes 10 and 12. Oxidatively induced-reductive elimination of 9a-c gave vinylcyclopropanecarboxylates 17a-c. The optically active vinylcyclopropane (+)-17a, prepared from (1S)-7, undergoes olefin cross-metathesis with excess (+)-18 to yield (+)-19, a C9C16 synthon for the antifungal agent ambruticin. Alternatively reaction of 7 with methanesulfonamide or trimethylsilylazide gave (E,E-diene)iron complexes 14d and e. Huisgen [3 + 2] cyclization of the (azidodienyl)iron complex 14e with alkynes afforded triazoles 25a-e