Practical synthesis of (E)- and (Z)-2-silyl-3-penten-1-ols with high enantiopurity

Practical methods for the synthesis of the optically active (E)- and (Z)-2-silyl-3-pentene-1-ols are described. The optically pure (E)-allylsilane was synthesized from commercially available (R)-3-butyn-2-ol in five steps involving hydrozirconation followed by alkylation of the resulting alkenylmetal with BnOCH₂Cl. On the other hand, both enantiomers of the corresponding (Z)-allylsilane were prepared from commercially available dimethylphenylvinylsilane through epoxidation, the regioselective epoxide-opening reaction with 1-propynylmagnesium bromide, and the subsequent optical resolution using a lipase.     

Isolation and characterization of microorganisms degrading nylon 4 in the composted soil

Two kinds of microorganisms, a bacterium (KT-1 strain) and a fungus (KT-2 strain), degrading nylon 4 (polyamide 4), which was easily prepared by the anionic ring-opening polymerization of 2-pyrrolidone, were isolated from the composted soil with the utilization of enrichment cultures and the culture using nylon 4 as a carbon source. KT-1 and KT-2 strains were identified as neighboring species to Stenotrophomonas sp. and Fusarium sp., respectively, by their morphological properties and the nucleotide sequences. These strains were confirmed to grow in the culture medium containing nylon 4 powders as a carbon source. In addition, nylon 4 film was decomposed in both mineral media containing KT-1 and KT-2 strains, respectively, and disappeared within two months. The MALDI TOF-MS analysis of nylon 4 recovered during the biodegradation test suggest that the isolated KT-2 strain recognize the acyllactam or carboxy chain end and degrade them or their neighboring amide bond.     

Cobalt‐Catalyzed Isomerization of 1‐Alkenes to (E)‐2‐Alkenes with Dimethylphenylsilylmethylmagnesium Chloride and Its Application to the Stereoselective Synthesis of (E)‐Alkenylsilanes

“Co”axing selectivity into isomerization : Treatment of 1‐alkenes with dimethylphenylsilylmethylmagnesium chloride in the presence of a cobalt‐NHC complex in dioxane at 50 °C or higher provides the corresponding (E)‐2‐alkenes selectively. The isomerization is applicable to the stereoselective synthesis of (E)‐crotylsilanes and (E)‐1‐propenylsilanes from the corresponding homoallylsilanes and allylsilanes, respectively.

     

Ab initio generic structures which are superstable but not ω-stable

Let L be a countable relational language. Baldwin asked whether there is an ab initio generic L-structure which is superstable but not ω-stable. We give a positive answer to his question, and prove that there is no ab initio generic L-structure which is superstable but not ω-stable, if L is finite and the generic is saturated.     

Polycarbonate Crystallization by Vapor‐Grown Carbon Fiber with and without Magnetic Field

Polycarbonate (PC)/vapor‐grown carbon fiber (VGCF™) composite was prepared through melt compounding. It was unexpectedly found from differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD) that the crystallization of PC was substantially accelerated in the presence of the ordered graphite surface of VGCF™. To make an aligned structure of PC crystallization together with the orientation of VGCF™, a magnetic field of 2.4 T was applied to the composite under several temperature profiles. The WAXD pattern revealed that not only dispersed VGCF™ but also matrix PC crystallization was magnetically aligned through the optimization of processes. The evidence for PC crystallization by VGCF™ with and without magnetic force is described.

Optical micrograph (a) and WAXD pattern (b) of PC/VGCF™ (95:5 wt. ratio) composite which was treated under a magnetic field (vertical direction) of 2.4 T under an optimized heating profile.