Preparation of a chiral hyperbranched polymer based on cinchona alkaloids and investigation of its catalytic activity in asymmetric reactions.

Cinchona alkaloid-derived sulfonamides and ester dimers containing chiral hyperbranched polymers have been successfully synthesized and applied as catalysts in asymmetric reactions. Several hyperbranched polymers derived from cinchona alkaloids, incorporating sulfonamides and esters, were synthesized through Mizoroki-Heck coupling polymerization. These polymers were subsequently applied in enantioselective Michael addition reactions.

Synthesis of cinchona urea polymers using Yamamoto coupling and their application to asymmetric reaction.

Cinchona urea compounds having 3,5-diiodophenyl moieties were subjected to Yamamoto coupling polymerization to afford the chiral urea polymers. These polymers showed high activities as heterogeneous catalysts in asymmetric Michael reactions comparable with those of the corresponding monomeric catalyst in solution systems. Furthermore, the polymeric catalysts are easily recovered from their reaction mixtures due to their insolubility and can be reused several times without loss of catalytic activity.

Simple production of resilin-like protein hydrogels using the Brevibacillus secretory expression system and column-free purification.

Resilin, an insect structural protein, has excellent flexibility, photocrosslinking properties, and temperature responsiveness. Recombinant resilin-like proteins (RLPs) can be fabricated into three-dimensional (3D) structures for use as cell culture substrates and highly elastic materials. A simplified, high-yielding production process for RLPs is required for their widespread application.

Autonomous Sequences in Myoglobin Emerging from X-ray Structure of Holomyoglobin.

The proposed continuous folding structure units are fundamental to analyze protein structure. Here, we could elucidate for the first time two types of hydrophobic core networks in apomyoglobin using continuous folding structure units. In myoglobin, two autonomous sequences emerged clearly.

Study on the performance of methyl methacrylate polymerization: Comparison of partially oxidized tri-n-butylborane and benzoyl peroxide with aromatic tertiary amines.

In this study, we examined the polymerization performance of methyl methacrylate (MMA) initiated with partially oxidized tri-nbutylborane (TBBO) compared to that initiated with benzoyl peroxide and aromatic tertiary amine (BPO/amine) system. In the bulk polymerization of MMA at 37°C, conversion initiated with TBBO after 3 h was nearly quantitative, whereas the conversion with the BPO/amine system was low (~20%). The number-averaged and weight-averaged molecular weight of the TBBO-initiated polymer was more than twice as high as that of the BPO/amine-initiated polymer.

Design of peptide-containing 5-unmodified neutral flavins that catalyze aerobic oxygenations.

Simulation of the monooxygenation function of flavoenzyme () has been long-studied with 5-modified cationic flavins ( ), but never with 5-unmodified neutral flavins () despite the fact that is genuinely equal to the active center of . This is because of the greater lability of 4a-hydroperoxy adduct of , , compared to those of , , and , . In this study, incorporated into a short peptide, flavopeptide (), was designed by a rational top-down approach using a computational method, which could stabilize the corresponding 4a-hydroperoxy adduct () through intramolecular hydrogen bonds.

Cinchona Squaramide-Based Chiral Polymers as Highly Efficient Catalysts in Asymmetric Michael Addition Reaction.

We have synthesized novel chiral polymers containing a cinchona-based squaramide in the main chain. We designed a novel cinchona squaramide dimer that contains two cinchona squaramide units connected by diamines. The olefinic double bonds in the cinchona squaramide dimer were used for Mizoroki-Heck (MH) polymerization with aromatic diiodides.

Protein Folding Structures: Formation of Folding Structures Based on Probability Theory.

To the best of our knowledge, this is the first study that shows that the X-ray structures of proteins can be dissected into their continuous folding structure units. Each folding structure unit was designed such that both the terminal di- or tri-peptide sequences shared common sequences with the two adjacent folding structure units. To encode the folding structure information of proteins into their amino acid sequences, we proposed 44 kinds of folding elements, which covered all of the amino acids in the protein chains, and defined all folding structure units.

Synthesis of main-chain chiral quaternary ammonium polymers for asymmetric catalysis using quaternization polymerization.

Main-chain chiral quaternary ammonium polymers were successfully synthesized by the quaternization polymerization of cinchonidine dimer with dihalides. The polymerization occurred smoothly under optimized conditions to give novel type of main-chain chiral quaternary ammonium polymers. The catalytic activity of the polymeric chiral organocatalysts was investigated on the asymmetric benzylation of N-(diphenylmethylidene)glycine tert-butyl ester.

Design of main-chain polymers of chiral imidazolidinone for asymmetric organocatalysis application.

Main-chain polymers of chiral imidazolidinone were successfully synthesized by reaction of chiral imidazolidinone dimers with disulfonic acid. Chiral imidazolidinones were incorporated into the main-chain of the polymer by ionic bonding. These polymers could be used as polymeric chiral organocatalysts for asymmetric Diels-Alder reactions.

Molecular design of chiral quaternary ammonium polymers for asymmetric catalysis applications.

Repeated reaction between a chiral quaternary ammonium dimer and disodium disulfonate gave a chiral ionic polymer, which showed excellent catalytic activity in the asymmetric benzylation of N-diphenylmethylene glycine tert-butyl ester.

Main-chain ionic chiral polymers: synthesis of optically active quaternary ammonium sulfonate polymers and their application in asymmetric catalysis.

A condensation reaction between quaternary ammonium halide and sulfonate was first successfully applied to the synthesis of the chiral polymers. Reaction of bis(quaternary ammonium halide) with disulfonate afforded a polymer containing ionic bonds in its main chain. The chiral ionic polymers were applied to the asymmetric benzylation of N-diphenylmethylidene glycine tert-butyl ester to prepare (S)-phenylalanine derivatives in high yield with a high level of enantioselectivity.

Development of biomedical porous titanium filled with medical polymer by in-situ polymerization of monomer solution infiltrated into pores.

Porous metallic materials can have a low Young's modulus, which is approximately equal to that of human bone, by controlling the porosity. On the other hand, certain medical polymers exhibit biofunctionalities that are not intrinsically present in metallic materials. Therefore, a composite consisting of these materials is expected to possess both these advantages for biomedical applications.

Asymmetric transfer hydrogenation of imines catalyzed by a polymer-immobilized chiral catalyst.

The asymmetric transfer hydrogenation of imines was performed with the use of a polymer-immobilized chiral catalyst. The chiral catalyst, prepared from crosslinked polystyrene-immobilized chiral 1,2-diamine monosulfonamide, was effective in the asymmetric transfer hydrogenation of N-benzyl imines in CH(2)Cl(2) to give a chiral amine in high yield and good enantioselectivity. Furthermore, an amphiphilic polymeric catalyst prepared from crosslinked polystyrene containing sulfonated groups successfully catalyzed the asymmetric transfer hydrogenation of cyclic imines in water.

Polymer-immobilized catalyst for asymmetric hydrogenation of racemic alpha-(N-benzoyl-N-methylamino)propiophenone.

Asymmetric hydrogenation of alpha-(N-benzoyl-N-methylamino)propiophenone through dynamic kinetic resolution was performed by using a polymer-immobilized chiral diamine-ruthenium-BINAP-t-BuOK system in order to yield syn-beta-amide alcohol exclusively with nearly perfect enantioselectivity.

Novel preparation method for poly(L-lactide)-based block copolymers: extended chain crystallites as a solid-state macro-coinitiator.

A novel synthetic method for poly(L-lactide) (PLLA)-based diblock copolymers was developed by the use of PLLA extended chain crystallites (or crystalline residues) as a solid-state macro-coinitiator. In this study, we showed one example, i.e.

Highly active and selective palladium catalyst for hydroesterification of styrene and vinyl acetate promoted by polymeric sulfonic acids.

Highly efficient, selective and recyclable palladium catalyst systems for hydroesterification of styrene and vinyl acetate were realized by using 1,2-bis(di-tert-butylphosphinomethyl)benzene as ligand and polymeric sulfonic acids of limited SO(3)H loadings as promoter.

Preparation of polymer-supported benzyllithium reagents.

Cross-linked polystyrenes (2, 8, and 11) possessing pendant double bonds conjugated with benzene ring were prepared by both polymerization method and chemical modification of pre-formed polymers. These double bonds were readily lithiated with n-butyllithium to give the benzyllithium species on the polymer. The polymer supported benzylic anions (3 and 12) are a versatile polymeric organometallic reagent that reacted with various kinds of electrophiles.