Polymers from 12 α-hydroxymethylabiet-7,8-enoic acid and vinyl 12 α-hydroxymethylabiet-7,8-enoate

12 α-Hydroxymethylabiet-7,8-enoic acid has been homopolymerized by melt condensation, and a partially crystalline polyester has been obtained. Vinyl 12 α-hydroxymethylabiet-7,8-enoate has been prepared from 12 α-hydroxymethylabiet-7,8-enoic acid by vinyl interchange with vinyl acetate and has been homopolymerized, copolymerized with vinyl chloride, vinyl acetate, butadiene, and acrylonitrile, and terpolymerized with styrene and acrylonitrile. Polymers thus obtained have been characterized.     

Thermal behavior of α nylon-12

The thermal behavior of α nylon-12 film cast from a phenol-ethanol mixture has been studied by differential scanning calorimetry. Polymorphism has been analyzed by x-ray diffraction. The γ form exhibits a single endothermic melting peak in the thermogram, whereas the α form exhibits double peaks. Samples with mixed α and γ forms show double peaks at the same positions and the area ratio changes in accordance with the amounts of the two forms. The appearance of the γ peak, even for the α sample, is explained by recrystallization to the γ form after melting of the α form. The melting point of α nylon-12 is ca. 173°C, which is lower by 6–7° than that of the γ form. Once the α or γ sample has been melted and then cooled, its heating thermogram shows a small peak before the appearance of the main peak. The small peak seems to be due to incomplete and/or smaller crystallites formed during cooling. Heat treatment below the melting point of α nylon-12 is effective in transforming the α form to the γ form, probably via a melt-recrystallization process.     

Contact between the β1 and β2 Segments of α‐Synuclein that Inhibits Amyloid Formation

Conversion of the intrinsically disordered protein α‐synuclein (α‐syn) into amyloid aggregates is a key process in Parkinson’s disease. The sequence region 35–59 contains β‐strand segments β1 and β2 of α‐syn amyloid fibril models and most disease‐related mutations. β1 and β2 frequently engage in transient interactions in monomeric α‐syn. The consequences of β1–β2 contacts are evaluated by disulfide engineering, biophysical techniques, and cell viability assays. The double‐cysteine mutant α‐synCC, with a disulfide linking β1 and β2, is aggregation‐incompetent and inhibits aggregation and toxicity of wild‐type α‐syn. We show that α‐syn delays the aggregation of amyloid‐β peptide and islet amyloid polypeptide involved in Alzheimer’s disease and type 2 diabetes, an effect enhanced in the α‐synCC mutant. Tertiary interactions in the β1–β2 region of α‐syn interfere with the nucleation of amyloid formation, suggesting promotion of such interactions as a potential therapeutic approach.     

A novel synthesis of α-hydroxy- and α,α′-dihydroxyketone from α-iodo and α,α′-diiodo ketone using photoirradiation

A novel reaction of α-iodo ketone (α-iodocycloalkanone, α-iodo-β-alkoxy ester, and α-iodoacyclicketone) with irradiation under a high-pressure mercury lamp gave the corresponding α-hydroxyketone in good yields. In the case of α,α′-diiodo ketone, α,α′-dihydroxyketone which little has been reported until now was obtained. This reaction affords a new, clean and convenient synthetic method for α-hydroxy- and α,α′-dihydroxyketone.     

Ring-opening polymerization of α,β-disubstituted oxiranes by α-methoxyphenylmethylium hexachloroantimonate

α-Methoxyphenylmethylium hexachloroantimonate was used as a novel initiator for the polymerization of α,β-disubstituted oxiranes such as cyclohexene oxide (CHO) and 2-butene oxide (trans and cis) (2-BO) at ?78°C with dichloromethane or dichloromethane-toluene mixtures as solvents. The CHO polymerization mixture became turbid and the polymer precipitated in dichloromethane. The CHO polymerization proceed quantitatively in dichloromethane–toluene mixtures. The molecular weight distribution of polyCHO obtained was bimodal regardless of the solvent used. The polymerization of trans-2-BO was heterogeneous in both dichloromethane and dichloromethane–toluene mixture. The polymerization mixtures of cis-2-BO were transparent but reached a limit yield which was less than the polymer yield of trans-2-BO. Furthermore, the microstructure of the poly2-BOs were analyzed by Vandenberg's method and the results confirmed Vandenberg's finding that inversion of configuration occurs in the propagation step.