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The first total syntheses of corallocins B and C are described herein. The Suzuki–Miyaura coupling was key to completion. Because these two natural products have been reported to induce neurotrophin expression in human astrocytes, they are expected to serve as new drug leads for neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

In this article, we report the synthesis of (±)-5- epi -vetiverianine A. The key reactions, including a rhodium-catalyzed coupling reaction and an oxidative phenolic cyclization, allow for efficient and stereoselective access to (±)-5- epi -vetiverianine A in 11 steps, and in 20% overall yield. The stereochemistry is confirmed by NOE studies. [ABSTRACT FROM AUTHOR]

In this report, we described the first total synthesis of (−)‐boscartin A, a cembranoid featuring a 5/5/12‐fused tricyclic structure. Via the key reactions, including stereoselective epoxidation and Wharton reaction, (−)‐Boscartin A was obtained in three steps from (−)‐boscartin F, with 46 % overall yield. [ABSTRACT FROM AUTHOR]

Herein, we describe the first total synthesis of cochlearol B, a meroterpenoid natural product featuring a 4/5/6/6/6‐fused pentacyclic structure. Key steps, oxidative cyclization and subsequent intramolecular [2+2] photocycloaddition, which constructed the pentacyclic structure in highly stereoselective manner, allowed efficient access to cochlearol B with the longest linear sequence of 16 steps, and in 9 % overall yield. Single‐crystal X‐ray crystallographic analysis clearly confirmed the stereochemistry of cochlearol B. [ABSTRACT FROM AUTHOR]

In this paper, the synthesis of the carbon skeleton of cotylenin A aglycone is described. The key reactions, including an intramolecular aldol reaction, an aldol coupling reaction, and a ring-closing meta-thesis, allow for the effective and stereoselective access to the carbon skeleton of cotylenin A aglycone. The stereochemistry was confirmed by single-crystal X-ray crystallographic analyses of related compounds. [ABSTRACT FROM AUTHOR]

We have developed a concise diastereoselective total synthesis of (±)-parvistemonine A. By using a Mukaiyama–Michael addition, an aza-Wittig reaction, a Paal–Knorr pyrrole synthesis, an acid-mediated annulation, and a Mitsunobu reaction as key steps, we achieved a total synthesis in which the longest linear sequence was ten steps and the overall yield was 19.6%. Additionally, the relative stereochemistry of parvistemonine A was confirmed by X-ray crystallographic analysis for the first time. [ABSTRACT FROM AUTHOR]

Highly diastereoselective total syntheses of (±)‐caseabalansin A (1) and (±)‐18‐epicaseabalansin A (2) are described in this paper. We revealed that the intramolecular Robinson‐type annulation of an alkynone was effective in the stereocontrolled construction of the bicyclic skeleton of 1 and 2. Further transformation of the resulting enone, including diastereoselective reduction by LiAlH(OtBu)3, hydroxy‐group‐directed hydrogenation, cyclization to form the cyclic acetal moiety, and introduction of a side chain by a C(sp3)−C(sp3) Stille coupling reaction, resulted in the total syntheses of (±)‐1 and (±)‐2. [ABSTRACT FROM AUTHOR]

Halogen bonding catalysis has recently gained increasing attention as a powerful tool to activate organic molecules. However, the variety of the catalyst structure has been quite limited so far. Herein, we report the first example of the use of an iodoalkyne as a halogen bond donor catalyst. By using an iodoalkyne bearing a pentafluorophenyl group as a catalyst, thioamides were efficiently activated and reacted with 2-aminophenol to generate benzoxazoles in good yield. Mechanistic studies, including 13C NMR spectroscopic analysis and several control experiments, provided concrete evidence that this catalytic activation is based on halogen bonding. Thus, the results obtained in this study demonstrate that iodoalkynes can serve as a new scaffold for future development of halogen bonding catalysis. [ABSTRACT FROM AUTHOR]

Abstract: Novel dipeptidyl peptidase IV (DPP-IV) inhibitors with a phenethylphenylphthalimide skeleton were prepared based on α-glucosidase inhibitors and liver X receptor (LXR) antagonists derived from thalidomide. Representative compounds showed non-competitive inhibition of DPP-IV and 28a exhibited 10-fold selectivity for DPP-IV over DPP-8. Compound 28a is the first non-competitive, selective DPP-IV inhibitor. [Copyright &y& Elsevier]

A polyol-ligand-containing porous hollow-fiber membrane capable of removing antimony(III) from a liquid stream was prepared by radiation-induced graft polymerization of an epoxy-group-containing vinyl monomer, glycidyl methacrylate(GMA), and subsequent functionalization with N-methylglucamine(NMG) and 3-amino-1,2-propanediol(APD). The resultant chelate-forming group density was 1.6 mol per kg of the NMG-group-containing porous hollow-fiber membrane. An antimony(III) oxide solution(10 mg per L, pH 3.6–13) was forced to permeate through the submicron-diameter pores of the chelating porous hollow-fiber membrane. The antimony concentration of the effluent penetrating the outside surface of the hollow fiber was determined as a function of the effluent volume. The breakthrough or dynamic adsorption capacity for antimony was 54 g of Sb per kg of membrane at pH 11. Because of negligible diffusional mass-transfer resistance, the breakthrough curves overlapped irrespective of the permeation rate of the antimony solution across the chelating porous hollow-fiber membranes. [ABSTRACT FROM AUTHOR]

A porous hollow fiber membrane with an average pore diameter of 360 nm and a porosity of 71% was used as a starting polymer. An epoxy-group-containing monomer, glycidyl methacrylate, was grafted onto the porous hollow fiber membrane by radiation-induced graft polymerization. The produced epoxy group was quantitatively converted into a 2-hydroxyethylamino group as an anion-exchange group by reaction with ethanolamine. Dextransucrase solution was forced to permeate radially outward through the pore from the inside surface of the porous hollow-fiber membrane to be immobilized by the grafted polymer chains based on an anion-exchange interaction. Subsequently, sucrose solution as substrate was fed to the inside surface of the dextransucrase- immobilized porous hollow fiber membrane. Dextran produced by the enzymatic reaction formed a skin layer on the inside surface of the membrane with a thickness of approximately 4 µm and an estimated pore diameter of 50 nm. [ABSTRACT FROM AUTHOR]

Phenyl isopropenyl ketone (PIPK) was terpolymerized with styrene and n-butyl acrylate. Clear 1.6 µm thick polymer layers coated on glass plates were found to be removed by 2-3 times of repeated cycles of 254 nm or 222 nm deep ultraviolet irradiation for 3 min at 80-120 °C and brushing-off. The polymer layer irradiated under some conditions could not be detached from the substrate, and crosslinking was observed to take place in parallel with degradation during the irradiation. From the experiments with PIPK-methyl methacrylate copolymer as a model polymer, the optimum PIPK content for easy detaching was found to be around 11 mol%. Further, the preferable light source and irradiation temperature were determined for effective photodegradation with suppressing photocrosslinking, and the reaction scheme was elucidated from UV-spectral and molecular-weight changes and quantum yields for benzoyl side-group removal and for main-chain scission. [ABSTRACT FROM AUTHOR]

Anion-exchange porous hollow-fiber membranes were prepared by graft polymerization of an epoxy group-containing monomer and subsequent ring-opening of the epoxide with diethylamine. Cycloisomaltooligosaccharide glucanotransferase (CITase) was bound by the anion-exchange polymer chains onto the membrane, and cross-linked with transglutaminase. CITase was immobilized at a density of 38 and 110 mg-CITase/g, equivalent to the degree of immobilized enzyme multilayering, which is defined by the ratio of the immobilized amount to the theoretical monolayer binding capacity, of 3.5 and 9.8, respectively. Seven- to nine-glucose-membered cycloisomaltooligosaccharides (CIs) were produced during the permeation of a dextran solution at various buffer concentrations, pHs, and temperatures through the pores rimmed by the CITase-immobilized polymer chains. Optimum pH and temperature were 6–7 and 323 K, respectively. The yield of CIs decreased with an increase in space velocity (SV), which is defined by dividing the permeation rate of the dextran solution by the membrane volume. A maximum yield of 45% was observed in the circulation mode under optimized reaction conditions. [Copyright &y& Elsevier]