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Methyl methacrylate (MMA)/N,N-dimethyl acrylamide (DMA) gradient copolymers with various chemical composition were synthesized by nitroxide-mediated controlled radical polymerization (NMP). Molecular weight (MW) characterization via gel permeation chromatography demonstrated that these materials were made in a “controlled” manner. The reactivity ratios values r1(MMA) = 2.36 and r2(DMA) = 0.33 were experimentally determined using the linear least-squares numerical method, results in good agreement with the literature. Characterization of the glass transition temperature, Tg, by differential scanning calorimetry (DSC) of gradient copolymers exhibited one Tg, with a value intermediate to the Tg of pure poly(methyl methacrylate) (PMMA) and poly(N,N-dimethyl acrylamide) (PDMA). In contrast, di- and triblock copolymers made of poly(n-butyl acrylate) (PBA) as central block and PMMA/PDMA gradient copolymer as external block yielded two Tg, one corresponding to the Tg of PBA and the other intermediate to the Tg of...

The synthesis of 2-isocephems bearing multiple bonds between the thiazoline ring and the 3-substituent is reported. When a leaving group was present, The E-vinylogous derivatives were shown to be more active than the parent compounds, essentially against staphylococci. Insertion of an aryl group in this position, however, sharply reduces the activity against Gram-negative bacteria.

Experimental results on electrical conductivity and thermoelectric power for FeCl3-doped polyvinyl alcohol-polypyrrole composites, with polypyrrole content exceeding the percolation threshold, are presented. The electrical conductivity is analyzed in terms of the hopping theory, whereas the thermoelectric power displays a metallic-like dependence. A model involving both the intrinsic resistance of the fibrils (V.R.H. hopping mechanisms) and the resistance of the junctions between fibrils (fluctuations-induced tunneling conduction) has been retained.

Enantioselective synthesis of the isocephem synthon 2 has been carried out by assembling 3 building blocks. Cycloaddition of phthalimido acetyl chloride with a chiral imine gave the β-lactam nucleus in 80% diastereoisomeric excess (d.e.). The elaboration of the thiazine ring was carried out using a highly functionalised epoxy ester 12 and P2I4 mediated water elimination.

Enantioselective synthesis of the isocephem synthon 2 has been carried out by assembling 3 building blocks. Cycloaddition of phthalimido acetyl chloride with a chiral imine gave the β-lactam nucleus in 80% diastereoisomeric excess (d.e.). The elaboration of the thiazine ring was carried out using a highly functionalised epoxy ester 12 and P2I4 mediated water elimination.

(3S,4S) 3-amino-4-fluoromethyl-azetidinone 9 is obtained conveniently from (R) N-(2-fluoroethylidene)-α-methylbenzylamine via cycloaddition.