Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
A preparative-scale asymmetric synthesis of (R)-α-fluorophenylacetic acid, a useful chiral derivatizing reagent, is described. Starting from ethyl α-bromophenylacetate, α-fluorophenylmalonic acid dipotassium salt was prepared in three steps (54% yield), including nucleophilic substitution by the fluoride ion as the keystep. Both the purified form and crude preparation of arylmalonate decarboxylase in E. coli worked well on this substrate, and (R)-α-flurophenylacetic acid (>99% e.e.) was prepared in a quantitative yield.
This contribution reports on the development and applications of a new family of next generation olefin polymerization catalysts for the creation of value-added olefin-based materials. Our own research based on a "ligand oriented catalyst design concept" has resulted in the discovery of new high-performance olefin polymerization catalysts named FI catalysts. FI catalysts in association with appropriate cocatalysts can exhibit a number of unique features, including exceptionally high ethylene insertion ability, high functional group tolerance, MAO- and borate-free polymerization catalysis and precise control over chain transfers. Due to these features, FI catalysts have created a wide variety of value-added olefin-based materials which include ethylene/polar monomer copolymers, ultrafine and noncoherent polyethylene (PE) particles, polyolefinic block copolymers and selective vinyl-terminated PEs. The vinyl-terminated PEs can readily be converted to well-defined terminally-functionalized PEs and PE/polyethylene glycol hybrid materials.
A short-step route to GlcNAc-Cbz-Asn was developed. Treatment of GlcNAc in sat. aq. NH4HCO3 solution and subsequent electorodialytic desalting provided ammonia-free glycosylamine in large quantity. The product was coupled with Cbz-Asn α-isobutyl ester β-fluoride, and finally, the isobutyl ester was deprotected by enzyme-catalyzed hydrolysis under mild conditions.
The introduction of two mutations (G74C/C188S) based on the estimated reaction mechanism resulted in the inversion of enantioselectivity of arylmalonate decarboxylase, which catalyses the asymmetric decarboxylation of arylmethylmalonate to give optically active arylpropionate.
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Abstract New well-defined polyethylene/poly(ethylene glycol) AB3-type hybrid materials have been developed, and the materials form nanosized particles in water (water dispersion, average particle size 18 nm) as a result of the self-assembly. This is the first example of nanosized particles comprised of polyolefin/polar polymer hybrid materials, which display unprecedented material properties.
