Diastereoselective Approach to cis-4-Methyl/thiol-Pipecolic Esters Based on RCM Reaction and Conjugate Michael Addition

A synthetic route for the access to enantiopure cis-4-methyl/thiol-pipecolic esters is presented. It is based on the ring-closing metathesis reaction to build the α,β-unsaturated piperidin-2-one derived from (S)-(–)-phenylethylamine, followed by either diastereoselective conjugate addition of methylorganocuprate allowing access to cis-4-methyl pipecolic ester or by tandem diastereoselective hydrosulforization–thionization reaction providing access to cis-4-thiol pipecolic ethyl esters.     

Novel self‐assembling polymeric system based on a hydrophobic modified copolymer: formulation,rheological characterization,and performance in enhanced heavy oil recovery

This work presents the chemical formulation and rheological properties of a novel self‐assembling polymer (SAP) system derived from a hydrophobically modified sulfonated polyacrylamide (HMSPAM). This polymeric association was established through complexation between the pendant hydrophobic groups contained in HMSPAM and β‐cyclodextrin molecules. The new SAP system offers improved viscoelastic properties because of the “interlocking effect” of the hydrophobic groups into β‐cyclodextrin cavities. It also provides suitable reformability upon mechanical shear when compared to the base HMSPAM. Furthermore, SAP exhibits superior tolerance to elevate brine salinity and hardness, as well as high reservoir temperature. Sandpack flooding tests conducted at simulated reservoir conditions (Pelican Lake reservoir, Alberta, Canada) indicate that this system shows superior mobility control (resistance factor) compared to HMSPAM. It also shows potential as in situ permeability modifier, which makes this polymeric system particularly suitable for heavy oil recovery applications. For instance, the newly developed SAP produced 20% more incremental heavy oil recovery if compared to the performance of the commonly used partially hydrolyzed polyacrylamide and 7% more incremental oil recovery than the baseline HMSPAM at the same experimental conditions. Overall, this new self‐assembly system shows potential for applications in heavy oil recovery. Copyright © 2014 John Wiley & Sons, Ltd.     

Rigid chain ribbon‐like metallopolymers

A set of new copolymers is here reported in which the repeating units are connected each other through Cu(II) metal centers. The coordination link is based on the bis‐chelating properties of salicylaldiminate groups of two different monomers. Due to their chemical structure, the two monomers afford, respectively, flexible and rigid repeating units in the metallocopolymers constitution upon coordination to copper centers. All the copolymers were soluble and easily processable. As shown by XRD analysis, rigid units' rich copolymers adopt a ribbon‐like structure in solid state in which highly planar strands of polymer stack thanks to π?π interactions, similarly to the polymer composed exclusively by rigid units. This behavior can be justified assuming the existence of a partial block character in copolymer constitution where long sequences of rigid units are alternated to sequences of flexible units. This assumption is supported also by DSC and UV–Vis analysis. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2412–2421     

Synthesis of p-amino-N,N′-dihydroxybenzamidine using a TBDMS protecting group protocol

A synthetic route to p-amino-N,N′-dihydroxybenzamidine is established using a TBDMS protecting group strategy starting with p-nitrobenzhydroxamic acid chloride, which is transformed to O,O′-bis(tert-butyldimethylsilyl)-N,N′-dihydroxybenzamidine. Reduction with sodium dithionite occurs without degradation of the dihydroxyamidine functional group. Deprotection with ammonium fluoride is fast and efficient. This is important because no other possibility to synthesize this derivative has been found up to now. Furthermore, TBDMS protecting group strategy is proved to be adaptable to other substituted N,N′-dihydroxybenzamidines.     

Pharmacophore modeling as an efficient tool in the discovery of novel noncompetitive AMPA receptor antagonists

A three-dimensional pharmacophore model for the binding of noncompetitive AMPA receptor antagonists was developed in order to map common structural features of highly active compounds. This hypothesis, which consists of two hydrophobic regions, one hydrogen bond acceptor and one aromatic region, was successfully used as framework for the design of a new class of allosteric modulators containing a tetrahydroisoquinoline skeleton and for in silico screening. The promising biological results suggested that the identified molecules might be useful "lead compounds" for future drug development.     

Micellar chromatographic determination of partition coefficients and associated thermodynamic data for pharmaceutical compounds

Micelle/water partition coefficients were obtained for procaine hydrochloride using micellar liquid chromatography (MLC) to illustrate the potential application of this technique to compounds of pharmaceutical interest. Experiments were conducted over a temperature range which led to calculation of a Gibbs free energy, enthalpy and entropy of transfer for procaine hydrochloride. Successful application of this technique was confirmed using a second compound over a range of temperatures, namely caffeine. Overall, this work confirms that MLC can be used to determine precise and accurate partition coefficients that possibly more closely mimic biological membranes than traditional in vitro systems, namely octanol/water.     

Multimethod analysis of Iranian Ilkhanate ceramics from the Takht-e Soleyman palace

The present work describes an analytical study performed on several pieces of Iranian Ilkhanate glazed ceramics from the Takht-e Soleyman palace (Iran, thirteenth century). Several advanced instrumental techniques, including pyrolysis–gas chromatography–mass spectrometry, Fourier transform IR spectroscopy, light microscopy, X-ray diffraction, scanning electron microscopy–X-ray microanalysis and voltammetry of microparticles, were used. The results obtained led to identification of the chemical and mineralogical composition of the pastes and glazes and the colouring agents. Corrosion processes associated with the extreme burial conditions in which the pieces remained for centuries were characterized in some areas of the glazes. A drying oil was identified as the main component of the organic material that was used as the adhesive for the decorative gold sheets applied on the glazes. This finding is in good agreement with traditional recipes. Interestingly, this drying oil exhibits an unusual composition as the gold sheet preserved it from external ageing agents (light, atmosphere, etc.).