Antifolate chemistry: synthesis of 4-[N-[(6RS)-2-methyl-4-oxo-3,4,7,8-tetrahydro-6H-cyclopenta[g]quinazolin-6-yl]-N-(prop-2-ynyl)amino]benzoic acid via a (propargyl)Co2(CO)6+ complex

A new route to compound 3 (4-[N-(6RS)-2-methyl-4-oxo-3,4,7,8-tetrahydro-6H-cyclopenta[g]quinazolin-6-yl]-N-(prop-2-ynyl)amino]benzoic acid), a crucial intermediate for the synthesis of potent inhibitors of thymidylate synthase (TS), is described. In this sequence the C6-N10 bond was constructed first, by the reductive amination of 5-acetamido-6-bromoindan-1-one 6 with tert-butyl 4-aminobenzoate, then the cyclopenta[g]quinazolinone ring was formed and the propargyl group was introduced on the N10-position using the (propargyl)Co2(CO)6+ complex as the electrophilic propargyl reagent.     

Analysis of post-Byzantine icons from the Church of the Assumption in Cephalonia, Ionian Islands, Greece: a multi-method approach

A multi-method approach has been developed for the characterisation of the proteinaceous binding media, drying oils and pigments present in samples from the panel paintings of the Church of the Assumption in Cephalonia (Ionian Islands, Greece). The analytical protocol involved the use of scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX), Raman spectroscopy and gas chromatography. The identification of the pigments was achieved by SEM/EDX and Raman spectroscopy. The latter technique was also used for the detection of the binding media, while their characterisation was achieved by gas chromatographic analysis of ethyl chloroformate derivatives. The aim of this multi-method protocol was to obtain as much information as possible from the panel paintings of the Church of the Assumption, through non-destructive methods, before proceeding to gas chromatography. Little scientific information is available for the understanding of the construction technique and the materials used by the post-Byzantine artists and whatever is available comes mainly from artists’ manuals. One of the aims of this paper is to provide a scientific background to the technology of the Ionian post-Byzantine icons.     

Chromeno[2,3-c]pyrroles by one-pot multicomponent domino addition–amination reaction

A new aspect concerning chromone chemistry leading to the one-pot synthesis of chromeno[2,3-c]pyrroles is described. The synthesis involves a multicomponent reaction of 3-formylchromones with isocyanides and azodicarboxylates, whereupon novel chromeno[2,3-c]pyrrole derivatives were formed in good yields. The structures of the products were elucidated by 1D and 2D NMR experiments and were unambiguously confirmed by the use of crystal X-ray diffraction analysis. Full assignment of all ¹H and ¹³C NMR chemical shifts has been achieved. A plausible mechanistic scheme is proposed.     

Simulation of polymer network formation: Connectivity considerations

The issue of connectivity in polymer networks is discussed by employing graph theory. Several topics are addressed, including the theory of rubberlike elasticity and computer simulations of network formation. The formulation of the partition function is reviewed and new applications are presented on the irradiation cure of polybutadiene and the sulfur vulcanization of cis(1,4)-polyisoprene and cis(1,4)-polybutadiene.     

Category-Theoretic Interpretative Framework of the Complementarity Principle in Quantum Mechanics

This study aims to provide an analysis of the complementarity principle in quantum theory through the establishment of partial structural congruence relations between the quantum and Boolean kinds of event structure. Specifically, on the basis of the existence of a categorical adjunction between the category of quantum event algebras and the category of presheaves of variable Boolean event algebras, we establish a twofold complementarity scheme consisting of a generalized/global and a restricted/local conceptual dimension, where the latter conception is subordinate to and constrained by the former. In this respect, complementarity is not only understood as a relation between mutually exclusive experimental arrangements or contexts of comeasurable observables, as envisaged by the original conception, but it is primarily comprehended as a reciprocal relation concerning information transfer between two hierarchically different structural kinds of event structure that can be brought into partial congruence by means of the established adjunction. It is further argued that the proposed category-theoretic framework of complementarity naturally advances a contextual realist conceptual stance towards our deeper understanding of the microphysical nature of reality.

     

Background spectral characteristics in direct sample insertion-inductively coupled plasma-mass spectrometry

An extensive set of background spectra are presented for a direct sample insertion-inductively coupled plasma-mass spectrometer (DSI-ICP-MS) system. These include spectra of a dry plasma (i.e. one in which no sample or solvent is introduced) and background spectra for DSI sample probes such as graphite, Mo and Ta cups as well as a W wire loop. Compared to the background spectra measured when aqueous solutions are nebulized into the plasma the DSI background spectra are considerably simpler. Primarily due to the elimination of water in DSI systems there is a significant reduction and even elimination of numerous background species, particularly those containing oxygen and hydrogen. In addition, the DSI sample probes themselves do not add any complex species to the spectral background.     

The cycloaddition of diethyl chlorophosphite with norbornadiene: Synthesis and crystal structure of the cycloadduct.

In the presence of Lewis acids, diethyl phosphorochloridite reacts with norbornadiene to afford the tetracyclic phosphinate ester 3 . The reaction is believed to involve formation of phosphenium ions stabilized only by alkoxy substituents. The cycloadduct of the reaction was characterized by its spectral data, by single crystal diffraction analysis of the parent acid, and ³¹P and ²⁷Al nmr experiments.     

Assignment of stereochemistry to cyclohexenylidenecyanoacetates by 1H NMR spectroscopy

The stereochemistry of various pairs of isomeric 2-cyclohexen-1-ylidenecyanoacetates was assigned using ¹H NMR spectroscopy. The isomers with the γ-methylene or the γ-vinyl protons cis to the carbalkoxy group were found to have the signals of these protons at approximately 0.3 ppm and 1 ppm, respectively, downfield relative to their geometrical isomers or the corresponding 2-cyclohexen-1-ylidenemalononitriles. The observation regarding the γ-vinyl proton proved useful for the assignment of configuration to cyclohex-enylidenecyanoacetates derived form cholest-4-en-3-one. The large and constant downfield shift (c. 1 ppm) of the γ-vinyl proton when cis to the ester group results from the rigid cyclohexenylidenecyanoacetate system, in which the vinylic proton can approach more closely to the magnetically anisotropic ester carbonyl group.     

Heteroannulation of naphthoquinones. Studies on the reaction of 2-bromo-2,3-dihydronaphthoquinone derivatives with 1,2-binucleophiles.

Heterocyclic derivatives of naphthoquinones were synthesized via their 2-bromo-2,3-dehydro-intermediates. This new route may lead to the formation of benzo[a]phenothiazin-5-ones, benzo[f]quinoxalin-6-ones as well as their 1,4 (or 7,10) dihydroxy-derivatives in high yields. The possible mechanisms involved in the formation of these compounds are discussed.     

Synthesis and characterization of 3D CoPt nanostructures

Cobalt platinum polypod-like nanostructures were synthesized by thermolytic reduction of Pt(acac)2 and Co(CH3COO)2 in oleylamine at 250 degrees C. The as-made CoPt nanopolypods are ferromagnetic, are soluble in nonpolar organic solvents, and reveal a coercive field of 525 and 1200 Oe at room temperature and 5 K, respectively.