Studies Directed Towards a Practical Synthesis of Brevicomins (II)1 : A Novel Synthesis of 1, 5-Dimethyl-8-Oxobicyclo [3.2.1]octane-6-one

The recent interest in pheromones,² as means of controlling insect pests, has prompted us to examine syntheses which could be both simple and practical. We recently reported a three-step synthesis of brevicomin (3), the aggregating pheromone of the pine bark beetle, Dendroctonus brevicomis.³     

1-(1-Alkenyl)benzotriazoles: Novel α-Hydroxyacyl Anion Equivalents for the Synthesis of α-Hydroxy Ketones

α-Lithiated 1-(1-alkenyl)benzotriazoles, generated from the reactions of 1-(1-alkenyl)benzotriazoles with n-BuLi, react with a variety of electrophiles to afford α-substituted 1-(1-alkenyl)benzotriazoles which undergo epoxidation with m-CPBA followed by hydrolysis to give α-hydroxy ketones in good yields. Thus, 1-(1-alkenyl)benzotriazoles behave as α-hydroxyacyl anion equivalents.     

Morphological Investigation of Midblock‐Sulfonated Block Ionomers Prepared from Solvents Differing in Polarity

Recent developments regarding charged multiblock copolymers that can form physical networks and exhibit robust mechanical properties herald new and exciting opportunities for contemporary technologies requiring amphiphilic attributes. Due to the presence of strong interactions, however, control over the phase behavior of such materials remains challenging, especially since their morphologies can be solvent‐templated. In this study, transmission electron microscopy and microtomography are employed to examine the morphological characteristics of midblock‐sulfonated pentablock ionomers prepared from solvents differing in polarity. Resultant images confirm that discrete, spherical ion‐rich microdomains form in films cast from a relatively nonpolar solvent, whereas an apparently mixed morphology with a continuous ion‐rich pathway is generated when the casting solvent is more highly polar. Detailed 3D analysis of the morphological characteristics confirms the coexistence of hexagonally‐packed nonpolar cylinders and lamellae, which facilitates the diffusion of ions and/or other polar species through the nanostructured medium.

     

Molecular theory of physical aging in polymer glasses

A molecular level theory for the physical aging of polymer glasses is proposed. The nonequilibrium time evolution of the amplitude of long wavelength density fluctuations, and its influence on activated barrier hopping, plays an essential role. The theory predicts temperature-dependent apparent power-law aging of the segmental relaxation time and logarithmic aging of thermodynamiclike properties, in good accord with experiments. A physical origin for the quantitative nonuniversal aspects based on the amplitude of quenched density fluctuations is suggested.     

Synthesis and Antiviral Properties of Spirocyclic [1,2,3]‐Triazolooxazine Nucleosides

An efficient synthesis of spirocyclic triazolooxazine nucleosides is described. This was achieved by the conversion of β‐D ‐psicofuranose to the corresponding azido‐derivative, followed by alkylation of the primary alcohol with a range of propargyl bromides, obtained by Sonogashira chemistry. The products of these reactions underwent 1,3‐dipolar addition smoothly to generate the protected spirocyclic adducts. These were easily deprotected to give the corresponding ribose nucleosides. The library of compounds obtained was investigated for its antiviral activity using MHV (mouse hepatitis virus) as a model wherein derivative 3 f showed the most promising activity and tolerability.     

Biochemical synthesis of water soluble polyanilines: Poly(p-aminobenzoic acid)

This report describes the synthesis of a water soluble polyaniline through a biochemical synthetic route. The oxidative free radical coupling mechanism for the synthesis of poly(p-aminobenzoic acid) is catalyzed by horseradish peroxidase in the presence of hydrogen peroxide. The resulting polymer is electrochemically active and undergoes reversible redox reactions. The polymer as synthesized is self doped and undergoes undoping in alkaline or ammonia solutions.