Sequential Photocatalysis for Homologative Diversification of α-Amino Acids to β-Amino Acids Via Phosphonium Ylide Linchpin Strategy.

β-Amino acids serve as crucial building blocks for a broad range of biologically active molecules and peptides with potential as peptidomimetics. While numerous methods have been developed for the synthesis of β-amino acids, most of them require multistep preparation of specific reagents and substrates, which limits their synthetic practicality. In this regard, a homologative transformation of abundant and readily available α-amino acids would be an attractive approach for β-amino acid synthesis.

Chemoselective Cleavage and Transamidation of Tertiary -Methoxybenzyl Amides under Metal-Free Photoredox Catalysis.

A metal-free and mild cleavage of tertiary -methoxybenzyl amides (PMB -amide) under photoredox conditions is developed using Mes-Acr-PhBF and Selectfluor to activate the electron-rich benzylic C-H bond of the PMB moiety. The resulting acyl fluoride intermediate is versatile and facilitates a one-pot transamidation of the PMB -amide. The value of this protocol is highlighted by performing the chemoselective activation of the PMB -amide in bifunctional molecules containing more reactive functionalities than the amide.

Asymmetric phase-transfer catalysis.

Over the past three decades, chiral phase-transfer catalysts (PTCs) have emerged as highly successful organocatalysts in a diverse range of asymmetric reactions. A substantial number of chiral PTCs have now already been discovered and utilized in dependable routes to enantioenriched products. These extend beyond the classical cationic PTCs with the emergence of anionic phase-transfer catalysis and hydrogen-bonding phase-transfer catalysis providing new asymmetric synthetic approaches.

Chemoselective Approach to Versatile Acyl Fluorides by Photoinduced Activation of -Methoxybenzyl Esters.

A new strategy for the metal-free photoinduced activation of -methoxybenzyl esters is developed using Selectfluor and benzil for the generation of acyl fluoride intermediates that enable various transformations. The highlight of this activation method is its high chemoselectivity in the presence of other functionalities, such as esters, amides, and ketones. A synthetic application for the preparation of peptide mimetics that possess two different amide units is also described.

Development of Axially Chiral Pyridylidene Amine Ligands and their Application in Pd-Catalyzed Enantioselective Allylic Substitution.

A series of novel axially chiral pyridylidene amine (PYE) ligands has been developed, and their catalytic capability has been demonstrated in various highly efficient and enantioselective Pd-catalyzed asymmetric allylic substitutions. A density-functional theory (DFT) study explains the preferential enantiocontrol in the key transition states of the axially chiral PYE ligand-promoted Pd-catalyzed allylic alkylation.

Catalytic 1,1-Cyanoalkylation of Electron-Deficient Olefins.

A catalytic 1,1-dicarbofunctionalization of electron-deficient olefins was effected on the basis of the three-component coupling reactions involving olefins bearing vicinal electron-withdrawing groups, potassium cyanide, and an alkyl halide, which afforded geminally cyanoalkylated products in high yields via conjugate cyanation, 1,2-proton transfer, and enolate alkylation. The use of suitable chiral phase-transfer catalysts enabled asymmetric induction in this transformation.

Synthetic utility of functionalized alkylsilyl peroxides for Fe-catalyzed and visible-light-promoted radical transformation.

α-Keto-, β-acetoxy- and β-amidoalkylsilyl peroxides are prepared from various precursors and utilized for Fe-catalyzed and visible-light-promoted radical functionalization with coupling partners under mild conditions with a broad substrate scope.

Asymmetric Phase-Transfer Alkylation of Readily Available Aryl Aldehyde Schiff Bases of Amino Acid Ethyl Esters.

Asymmetric phase-transfer alkylation of the -(arylmethylene)-α-alkylamino acid ethyl esters and -(arylmethylene)glycine ethyl esters was found to be catalyzed by the ()- or ()-Simplified Maruoka Catalyst with high efficiency and excellent enantioselectivity. This approach was successfully applied to the enantioselective formal synthesis of the angiotensin II type 2 receptor (AT2R) antagonists Olodanrigan and LX9211, and the practical aspect is demonstrated by the kilogram-scale synthesis of a key intermediate for the synthesis of LX9211.

Photoredox-Mediated Aerobic Oxidative Cleavage of 1,3-Diketones to Access 1,2-Diketones and ()-1,4-Enediones.

An aerobic oxidative cleavage of 1,3-diketones under visible light irradiation using an organic dye as a photocatalyst is disclosed. The newly developed reaction provides practical access to 1,2-diketones and ()-1,4-enediones in moderate to good yields with absolute regio- and stereoselectivity. Mechanistic studies of the reaction suggest that tetraketone intermediates might undergo a photocatalytic energy transfer from the excited photocatalyst to form biradical-like (n,π*) states of ketones.

Facile synthesis of 1,2-aminoalcohols α-C-H aminoalkylation of alcohols by photoinduced hydrogen-atom transfer catalysis.

1,2-Aminoalcohols are common motifs found in a wide range of natural products and pharmaceutical compounds. Here we report a photocatalytic method for the direct conversion of readily available aliphatic alcohols into synthetically valuable 1,2-aminoalcohols. A dual catalytic system consisting of an acridinium photoredox catalyst and a cationic hydrogen-atom transfer (HAT) catalyst based on 1,4-diazabicyclo[2.

Lymphatic Transport and Immune Activation Effect by Locally Administered Extracellular Vesicles from Saccharomyces cerevisiae as Biocompatible Vaccine Adjuvants.

The yeast strain Saccharomyces cerevisiae is an eukaryotic organism that has been widely used for the production of fermented foods. Most cells secrete extracellular vesicles (EVs), small particles composed of lipid membranes. Elucidating the role of EVs as a new intercellular communication system and developing novel EV-based therapies have attracted the increased attention of researchers.

Bidirectional Elongation Strategy Using Ambiphilic Radical Linchpin for Modular Access to 1,4-Dicarbonyls via Sequential Photocatalysis.

Organic molecules that can be connected to multiple substrates by sequential C-C bond formations can be utilized as linchpins in multicomponent processes. While they are useful for rapidly increasing molecular complexity, most of the reported linchpin coupling methods rely on the use of organometallic species as strong carbon nucleophiles to form C-C bonds, which narrows the functional group compatibility. Here, we describe a metal-free, radical-mediated coupling approach using a formyl-stabilized phosphonium ylide as a multifunctional linchpin under visible-light photoredox conditions.

Total Synthesis of Azulene Derivative, a Blue Pigment Isolated from , and Colorant Application of Its Aqueous Dispersion.

Safety concerns in the food industry have increased the demand for natural food colorants. However, the application ranges of natural blue colorants are insufficient because they are scarce in nature, and the currently available natural blue dyes are limited to water-soluble products. In this study, we investigated a fat-soluble azulene derivative isolated from the mushroom as a potential candidate for a natural blue colorant.

Impact of Catalyst Deuteration on the Reactivity of Chiral Phase-Transfer Organocatalysts.

Site-specifically deuterated organocatalysts were prepared and found to show improved reactivity over the non-deuterated analogs. Two privileged C -symmetric chiral binaphthyl-modified tetraalkylammonium salts were selected for this study. The stability of these phase-transfer catalysts was generally improved by site-specific deuteration, though the degree of improvement was structure dependent.

Synthetic Utility of Alkyl -Butyl Peroxides in a Copper-Catalyzed Radical Functionalization.

Alkyl -butyl peroxides are prepared from the corresponding -alkyl precursors and -butyl hydroperoxide in the presence of a promoter. These substrates can be utilized in a mild copper-catalyzed radical functionalization that utilizes several coupling partners and has a broad substrate scope. A mechanistic study suggests that alkyl radical species participate in the coupling reactions.

Recent Asymmetric Phase-Transfer Catalysis with Chiral Binaphthyl-Modified and Related Phase-Transfer Catalysts over the Last 10 Years.

In this personal account, we describe our recent advances in the three types of phase-transfer catalysis for various transformations including asymmetric induction: Firstly, asymmetric phase-transfer catalysis with Maruoka-type C -symmetric chiral biaryl-modified tetraalkylammonium salts and phosphonium salts; Secondly, asymmetric phase-transfer catalysis under base-free and neutral conditions; Thirdly, hydrogen-bonding catalysis using tetraalkylammonium and trialkylsulfonium salts. These three different strategies are illustrated by using various phase-transfer catalyzed transformations.

Database of fish fauna in a highly urbanised river (Tsurumi River Basin, Kanagawa, Japan).

Background: Urbanisation has facilitated changes in the hydrological cycle, sediment dynamics and habitat loss and it has had a tremendous impact on river ecosystems. Moreover, the invasion of non-native species reduces the number of native species with the progress of urbanisation, thereby resulting in the homogenisation of fish fauna and significant decrease in diversity. However, the effects of urbanisation on fish fauna vary depending on the region, degree of urbanisation and number of years since the construction of the city.

-Methoxybenzyl-Radical-Promoted Chemoselective Protection of -Alkylamides.

The hitherto difficult site-selective -methoxybenzylation of secondary amides using -methoxybenzylated alkylsilyl peroxides as a novel -methoxybenzylation agent under copper catalysis is reported. The reaction proceeds under mild reaction conditions in a highly chemoselective manner. This approach was successfully applied to the site-selective -methoxybenzylation of peptides.

Functional Characterization of Extracellular Vesicles from Baker's Yeast Saccharomyces Cerevisiae as a Novel Vaccine Material for Immune Cell Maturation.

Extracellular vesicles (EVs) encapsulate various bioactive molecules, and much effort has been directed towards developing a novel EV-based therapy. Although recent studies reported the secretion of EVs from probiotics baker's yeast Saccharomyces cerevisiae (S. cerevisiae), their properties and functions remain obscure.

VCD spectroscopy distinguishes the enamine and iminium ion of a 1,1'-binaphthyl azepine.

We present a VCD spectroscopic characterization of a chiral 1,1'-binaphthyl azepine catalyst and show that the VCD spectra of an generated enamine and an prepared iminium ion are characteristically different. The study highlights the potential of VCD spectroscopy to distinguish such catalytically relevant stable intermediates and that the spectra can be used to determine the species' dominant conformers in solution.

Fe-Catalyzed Three-Component Coupling Reaction of α,β,γ,δ-Unsaturated Carbonyl Compounds and Conjugate Dienes with Alkylsilyl Peroxides and Nucleophiles.

An Fe(OTf)-catalyzed three-component coupling reaction of α,β,γ,δ-unsaturated carbonyl compounds with alkylsilyl peroxides in the presence of certain heteronucleophiles (ROH and indole) is realized under mild reaction conditions. A variety of α,β,γ,δ-diene carbonyl substrates with different substituents were successfully employable via combination with several different alkylsilyl peroxides. This new approach is also applicable to the double functionalization of diene substrates.

Fe-Catalyzed Dicarbofunctionalization of Vinylarenes with Alkylsilyl Peroxides and β-Keto Carbonyl Substrates.

The formation of two carbon-carbon bonds using vinylarenes with alkylsilyl peroxides and β-keto carbonyl substrates is effected by the presence of catalytic Fe(OTf) under mild reaction conditions. A variety of vinylarenes with different substituents can be utilized in combination with several different alkylsilyl peroxides and β-keto carbonyl substrates.