Design of readily accessible, noncovalently tunable, and versatile chiral organic salt catalysts incorporating achiral phosphoric acid diesters


Synthesis of naphthalene-fused imidazo[1,2-a]pyridinium salts showing green luminescence with high quantum yields and large Stokes shift

We have synthesized naphthalene-fused imidazo[1,2-a]pyridines by a novel electrophilic iodocyclization of 2-alkynyl-3-arylimidazo[1,2-a]pyridines. Notably, their quaternized salts exhibited green emission with unexpectedly high quantum yields and mega-large Stokes shift and were successfully used for mitochondrial imaging.


Blue Luminescent Boron Complexes Based on N,N-Type Imidazo[1,5-a]pyridine Ligand for Mitochondrial Imaging


Mechanochemical transformation of tetraaryl[3]cumulenes to benzofulvenes via electrophilic iodocyclization


Synthesis of Alkynyl Spacer-Containing Chiral Polyguanidines and Their Noncovalent Modification for Organocatalyst Design


Divalent metal complexes of N,O- and N,N-bidentate imidazo[1,5-a]pyridine ligands: Synthesis, crystal structures, and photophysical properties


Immobilization of a flavin molecule onto poly(methacrylic acid)s and its application in aerobic oxidation catalysis: effect of polymer stereoregularity


Low-Voltage-Driven Electrochemical Aerobic Oxygenation with Flavin Catalysis: Chemoselective Synthesis of Sulfoxides from Sulfides


Effect of Phenolic Substituent Position in Boron Complexes of Imidazo[1,5-a]pyridine


Noncovalent Modification Strategy with Achiral Phosphoric Acid Diesters for Designing a Chiral Brønsted Base Organocatalyst

Bulletin of the Chemical Society of Japan


Synthesis of Optically Active Polyguanidines by Polyaddition Reaction of Biscarbodiimides with Chiral Diamines


Unexpected Formation of Poly-Functionalized Fulvenes by Reaction of a Tetraaryl[5]cumulene with Iodine


Synthesis of D-π-A type benzothiazolepyridinium salt composite and its application as photo-degradation agent for amyloid fibrils

We have synthesized a cyan fluorescent benzothiazole-pyridinium salt composite based on D-p-A architecture. This salt was found to work as not only a two- and three-photon excitable fluorophore but also a degradation agent against amyloid fibrils under LED irradiation conditions.

Bioorganic & Medicinal Chemistry Letters


Two-photon excitable boron complex based on tridentate imidazo[1,5-a]pyridine ligand for heavy- atom-free mitochondria-targeted photodynamic therapy


Effect of Stereochemistry on the Catalytic Activity of Flavopeptides


Alloxazinium-Resins as Readily Available and Reusable Oxidation Catalysts


Facile Construction of Benzofulvene Scaffold from Tetraaryl[3]cumulene via Electrophilic Iodocyclization


Synthesis and Optical Property of Quadrupolar Pyridinium Salt and Its Application as Bioimaging Agent


Two- and three-photon excitable quaternized imidazo[1,2-a]pyridines for mitochondrial imaging and potent cancer therapy agent


Determination of acid dissociation constants of flavin analogues by capillary zone electrophoresis

Acid dissociation constants (pK ) of nine kinds of flavin analogues as molecular catalyst candidates were determined by CZE. Although some of the analogues are instable and degradable under the light exposure or in alkaline aqueous solutions, the effective electrophoretic mobility of the flavin analogue of interest has been measured with the residual substance. The pK values of the flavin analogues were analyzed through the changes in the effective electrophoretic mobility with varying pH of the separation buffer. One or two steps pK values were determined by the analysis. One of the degraded species from the flavin analogues, lumichrome, was also detected in the CZE analysis, and its pK values were also determined. While coexisting impurities generated over the storage conditions were found in some analogues, the pK values of the target analogues were successfully determined with the help of the CZE separations. A pressure-assisted CZE was utilized for the determination or the estimation of the pK values of such analogues as possessing carboxylic acid moiety.


Visible-light-induced oxidative coupling reaction of benzylic amines using iridium(III) complex of pincer type imidazo[1,5-a]pyridine ligand


An Uncommon Use of Irradiated Flavins: Brønsted Acid Catalysis


Preparation of Flavin-Containing Mesoporous Network Polymers and Their Catalysis


Nucleophilic Addition to Nitrones Using a Flow Microreactor


Efficient Use of Photons in Photoredox/Enamine Dual Catalysis with a Peptide-Bridged FlavinAmine Hybrid

An isoalloxazine (flavin) ring system and a secondary amine have been integrated through a short peptide linker with the aim of using photons as efficiently as possible in photoredox/enamine dual catalysis. We herein report a peptide-bridged flavin-amine hybrid that can catalyze α-oxyamination of aldehydes with TEMPO under weak blue light irradiation to achieve an extremely high quantum yield of reaction (Φ = 0.80).


Fluorescent Imidazo[1,5-a]pyridinium Salt for a Potential Cancer Therapy Agent


Flavinium and Alkali Metal Assembly on Sulfated Chitin: A Heterogeneous Supramolecular Catalyst for H2O2-Mediated Oxidation


Suppression of protein adsorption on a graphene surface by phosphorylcholine functionalization


Synthesis and Transformations of Nitrones for Organic Synthesis


Aggregation induced Substrate Specificity in Aerobic Reduction of Olefins with Ultrasound Gel Catalyst of Synthetic Flavin


Greener Preparation of 5-Ethyl-4a-hydroxyisoalloxazine and Its Use for Catalytic Aerobic Oxygenations


Enzyme-like Regiodivergent Behavior of a Flavopeptide Catalyst in Aerobic Baeyer-Villiger Oxidation

We recently developed a flavopeptide immobilized on polystyrene resin, , that could realize the first 5-unmodified neutral flavin ()-catalyzed aerobic oxygenation reactions under non-enzymatic conditions. Although a key active species is assumed to be the corresponding 4a-hydroperoxyflavin () from the unprecedented activity and unique chemoselectivity, further circumstantial support would be helpful to be sure since spectroscopic evidence is difficult to obtain due to the compound's insolubility. In this article, we report that the aerobic Baeyer-Villiger oxidation of a fused cyclobutanone, (±)--bicyclo[3.2.0]hept-2-en-6-one (), can be promoted with in a FMO-like chemoselectivity and regiodivergent manner -related catalytic intermediates, which delivers strong evidence of the involvement of as an active species in -catalyzed aerobic oxygenation reactions.


Advanced Flavin Catalysts Elaborated with Polymers


Design of Peptide-Containing N5-Unmodified Neutral Flavins That Catalyze Aerobic Oxygenations


Brønsted Acid Catalysed Aerobic Reduction of Olefins by Diimide Generated In Situ from Hydrazine


Synthesis of Insoluble Polystyrene-Supported Flavins and Their Catalysis in Aerobic Reduction of Olefins

Journal of Polymer Science Part A: Polymer Chemistry


Facile Preparation of Flavinium Organocatalysts

We developed a safe, simple, inexpensive, and environmentally benign method for preparing N(5)-ethylated flavinium organocatalysts without using hazardous reagents or inert conditions as previously required. 5-Ethyl-3-methyllumiflavinium cation was prepared from its reduced form by NaNO2 -free aerobic oxidation, which was subsequently extracted onto commercial cation-exchange resins under NaClO4 -free conditions. The resulting resin-immobilized flavinium salts were found to be effective organocatalysts for aerobic oxidation reactions.


Biomimetic flavin-catalysed reactions for organic synthesis

Using simple riboflavin related compounds as biomimetic catalysts, catalytic oxidation of various substrates with hydrogen peroxide or molecular oxygen can be performed selectively under mild conditions. The principle of these reactions is fundamental and will provide a wide scope for environmentally benign future practical methods.


Highly Fluorescent Flavins: Rational Molecular Design for Quenching Protection Based on Repulsive and Attractive Control of Molecular Alignment

Unprecedented intense fluorescent emission was observed for a variety of flavin compounds bearing a perpendicular cyclic imide moiety at the C7 position of an isoalloxazine platform. A series of alloxan-substituted flavins was prepared selectively by reduction of the corresponding N-aryl-2-nitro-5-alkoxyanilines with zinc dust and subsequent reaction with alloxan monohydrate in the presence of boric acid. Analogues bearing oxazolidine-2,4-dione functionality were obtained on methylation of the alloxan-substituted flavins with methyl iodide and subsequent rearrangement in the presence of an inorganic base. The flavin compounds exhibit intense white-green fluorescent emission in the solution state under UV excitation at 298 K, with emission efficiencies Φ298 K greater than 0.55 in CH3 CN, which are higher than the values for all reported flavin compounds under similar conditions. The highest Φ298 K value of 0.70 was obtained in CH3 CN for isoalloxazine bearing C7-alloxan and N10-2,6-diisopropylphenyl groups. The temperature dependence of the emission intensities indicates that the pronounced emission properties at 298 K are attributable to the highly heat resistant properties towards emission decay with increasing temperature. Mechanistic studies, including X-ray diffraction analysis, revealed that the good emission properties and high heat resistance of the alloxan-substituted flavins are due to a synergetic effect of the associative nature of the C7-alloxan unit and the repulsive nature of the perpendicular bulky substituents at the C7 and N10 positions.


Controlled Physical Gelation of Thermoresponsive Poly(2-propionamidoacrylic acid) Aqueous Solution


Flavin-Functionalized Gold Nanoparticles as an Efficient Catalyst for Aerobic Organic Transformations


Ring-expanding Metathesis Oligomerization of Cyclic Nitrones


フラビン触媒を用いた酸素酸化システムの開発

フラビン触媒を用いた酸素酸化システムの開発


Oxidation of sulfides with hydrogen peroxide catalyzed by synthetic flavin adducts with dendritic bis(acylamino)pyridines


Non-Covalently Dendronized Flavins as Organocatalysts for Aerobic Reduction of Olefins


Oxidation of Sulfides with Hydrogen Peroxide Catalyzed by Vitamin B2 Derivatives


Aerobic Oxidation of Sulfides with Vitamin B2-derived Organocatalyst


Flavin-catalyzed aerobic oxidation of sulfides in aqueous media


Aerobic Reduction of Olefins by In Situ Generation of Diimide with Synthetic Flavin Catalysts

A versatile reducing agent, diimide, can be generated efficiently by the aerobic oxidation of hydrazine with neutral and cationic synthetic flavin catalysts 1 and 2. This technique provides a convenient and safe method for the aerobic reduction of olefins, which proceeds with 1 equiv of hydrazine under an atmosphere of O(2) or air. The synthetic advantage over the conventional gas-based method has been illustrated through high hydrazine efficiency, easy and safe handling, and characteristic chemoselectivity. Vitamin B(2) derivative 6 acts as a highly practical, robust catalyst for this purpose because of its high availability and recyclability. Association complexes of 1b with dendritic 2,5-bis(acylamino)pyridine 15 exhibit unprecedented catalytic activities, with the reduction of aromatic and hydroxy olefins proceeding significantly faster when a higher-generation dendrimer is used as a host pair for the association catalysts. Contrasting retardation is observed upon similar treatment of non-aromatic or non-hydroxy olefins with the dendrimer catalysts. Control experiments and kinetic studies revealed that these catalytic reactions include two independent, anaerobic and aerobic, processes for the generation of diimide from hydrazine. Positive and negative dendrimer effects on the catalytic reactions have been ascribed to the specific inclusion of hydrazine and olefinic substrates into the enzyme-like reaction cavities of the association complex catalysts.


フラビン有機分子触媒による環境調和型酸化反応

フラビン有機分子触媒による環境調和型酸化反応


Neutral Flavins: Green and Robust Organocatalysts for Aerobic Hydrogenation of Olefins

Various olefins can be hydrogenated quantitatively with neutral flavin 2 catalysts in the presence of 1-2 equiv of hydrazine under 1 atm of O(2). Vitamin B(2) derivative 2g acts as a highly efficient and robust catalyst for the present environmentally benign process producing water and nitrogen gas as the only waste products.


Sequential asymmetric homoallenylation of primary amines with a palladium catalyst


Synthesis and electrochemical behavior of clothespin-shaped bisflavin compounds


Flavins as organocatalysts for environmentally benign molecular transformations

Recent progress in the development of flavin-catalyzed oxidations and related reactions is described with respect to scope, limitation, and reaction mechanism. The 4a-hydroperoxyflavins, which are the most simplified model compounds of flavoenzymes, act as catalytically active species for the oxidation of organic substrates with the help of H(2)O(2) or O(2) as a mild oxidant. This principle behind the simulation of flavoenzymes led to the discovery of a variety of environmentally benign, oxidative transformations of secondary amines to nitrones, tertiary amines to N-oxides, sulfides to sulfoxides, and Baeyer-Villiger oxidations of ketones. Asymmetric oxidation of sulfides can also be performed with several chiral flavin catalysts. One of the fortunate outcomes of this study is the development of an environmentally friendly ("green") method for the "aerobic hydrogenation" of olefins, which is achieved by in situ generation of diimide with the aid of the flavin-catalyzed oxidation of hydrazine under an O(2) atmosphere.


Oxidation of sulfides with hydrogen peroxide catalyzed by 10,10'-linked bisflavinium perchlorates


Flavin-Catalyzed Oxidation of Amines and Sulfides with Molecular Oxygen: Biomimetic Green Oxidation

Flavin-catalyzed green oxidation of heteroatom compounds such as sulfides and amines with molecular oxygen and even air in the presence of hydrazine monohydrate in a fluorous solvent such as 2,2,2-trifluoroethanol at room temperature gives the corresponding oxidation products highly efficiently and selectively along with water and molecular nitrogen, which are environmentally benign by-products. The proposed reaction mechanism is based on the kinetics, solvent effect, and redox properties of flavin catalysts.


Palladium-Catalyzed Asymmetric Amination and Imidation of 2,3-Allenyl Phosphates

[reaction: see text] Asymmetric amination of 2,3-allenyl phosphates with nitrogen nucleophiles such as amines, hydroxylamines, and imides can be performed efficiently using a combination of zerovalent palladium complexes and SEGPHOS or MeOBIPHEP ligand, affording the corresponding optically active 1-aminated derivatives with enantiomeric excess of up to 97% ee.


Flavin-Catalyzed Generation of Diimide: An Environmentally Friendly Method for the Aerobic Hydrogenation of Olefins

The first green and practical method for "aerobic hydrogenation" involving the use of hydrazine and an organocatalyst is described. Olefins can be hydrogenated by treatment with hydrazine in the presence of a 5-ethyl-3-methyllumiflavinium perchlorate (FlEt+.ClO4-) catalyst under O2 atmosphere to give the corresponding hydrogenated products in excellent yields along with environmentally benign water and molecular nitrogen as the only waste products.

Journal of the American Chemical Society


Aerobic, Organocatalytic, and Chemoselective Method for Baeyer-Villiger Oxidation


Flavin Catalyzed Oxidations of Sulfides and Amines with Molecular Oxygen

Novel biomimetic, aerobic oxidation with an organocatalyst was performed. The oxidations of organic substrates such as sulfides, secondary amines, N-hydroxylamines, and tertiary amines with molecular oxygen (1 atm) or even in air in the presence of 5-ethyl-3-methyllumiflavinium perchlorate catalyst and hydrazine monohydrate in 2,2,2-trifluoroethanol occur highly efficiently to give the corresponding oxidized compounds in excellent yields along with water and molecular nitrogen, which are environmentally benign. The TON of the oxidation of sulfides amounts to 19 000.


Asymmetric Baeyer -Villiger Reaction with Hydrogen Peroxide Catalyzed by a Novel Planar-Chiral Bisflavin


Enantioselective Addition of Ketene Silyl Acetals to Nitrones Catalyzed by Chiral Titanium Complexes. Synthesis of Optically Active b-Amino Acids

A chiral titanium complex, Ti(O-i-Pr)(4)/BINOL/tert-butylcatechol, catalyzes enantioselective addition reaction of ketene silyl acetals to nitrones to give optically active beta-amino acid derivatives which are biologically active compounds and useful synthetic intermediates of natural products and pharmaceuticals such as beta-lactam antibiotics. The combined process of catalytic oxidation of secondary amines and enantioselective carbon-carbon bond formation of nitrones thus obtained with ketene silyl acetals provides a useful two-step method for the synthesis of optically active beta-amino acid derivatives and related nitrogen compounds.


Palladium-Catalyzed Asymmetric Alkylation of 2,3-Alkadienyl Phosphates. Synthesis of Optically Active 2-(2,3-Alkadienyl)malonates


Asymmetric Synthesis of b-Amino Acids by Addition of Chiral Enolates to Nitrones via N-Acyloxyiminium Ions

Bulletin of the Chemical Society of Japan


Synthesis of Homochiral -Sulfinyl Nitrones and Their Application for Enantioselective Synthesis of (+)-Euphococcinine


Regioselective Synthesis of Nitrones by Decarboxylative Oxidation of N-Alkyl--amino Acids and Application to the Synthesis of 1-Azabicyclic Alkaloids


Reversal of Diastereoselectivity of the Reaction of Chiral Boron and Titanium Enolates with Nitrones via N-Acyloxyiminium Intermediates. Asymmetric Synthesis of Diastereomeric a-Substituted b-Amino Acids


Asymmetric Synthesis of b-Amino Acids by Addition of Chiral Enolates to N-Acyloxyiminium Ions and Application for Synthesis of Optically Active 5-Substituted 8-Methylindolizidines


Highly Diastereoselective Addition of a Chiral Ketene Silyl Acetal to Nitrones: Asymmetric Synthesis of b-Amino Acids and Key Intermediates of b-Lactam Antibiotics


Synthesis of (R)- and (S)-3-(tert-butyldimethylsilyloxy)-1-pyrroline N-oxides chiral nitrones for synthesis of biologically active pyrrolidine derivative, Geissman-Waiss lactone


Palladium-Catalyzed Asymmetric Alkoxycarbonylation of Allyl Phosphates


Palladium-Catalyzed Carbonylation of Propargylamines. Selective Insertion of Carbon Monoxide into a Carbon-Nitrogen Bond


Palladium-Catalyzed Regioselective Carbonylation of 2,3-Dienylamines to g-Vinylacrylamides


Palladium-Catalyzed Double and Single Carbonylations of b-Amino Alcohols. Selective Synthesis of Morpholine-2,3-diones and Oxazolidin-2-ones and Applications for Synthesis of a-Oxo Carboxylic Acids


Tungstate-Catalyzed Decarboxylative Oxidation of N-Alkyl-a-amino Acids: An Efficient Method for Regioselective Synthesis of Nitrones


Titanium(III)-Induced Transformation of Hydroxylamines to Imines or Secondary Amines


Copper(I)-Catalyzed Amination of Propargyl Esters. Selective Synthesis of Propargylamines, 1-Alken-3-ylamines, and (Z)-Allylamines

Copper(I)-catalyzed aminations of propargyl phosphates and acetates proceed under mild reaction conditions to give the corresponding propargylamines which are precursors of 1-alken-3-ylamines and (Z)-allylamines.


Palladium-Catalyzed CarbonyIation of Allylamines. Synthesis of b,g-Unsaturated Amides by One-Carbon Homologation of Allylamines


Asymmetric 1,3-Dipolar Cycloaddition of Cyclic Nitrones to Crotonic Acid Derivatives Bearing Chiral Auxiliaries. Synthesis of Optically Active b-Amino Acids, (+)-Sedridine, and (+)-Hygroline


Aza- and oxacarbonylations of ally1 phosphates catalyzed by rhodium carbonyl cluster. Selective synthesis of b,g-unsaturated amides, esters, and acids


Palladium(0)-Catalyzed Alkoxycarbonylation of Allyl Phosphates and Acetates


Osmium-catalyzed Asymmetric Dihydroxylation of Olefins Using Chiral Isoxazolidine Ligands


Oxidation of Secondary Amines to Nitrones: 6-Methyl-2,3,4,5-tetrahydropyridine N-Oxide


パラジウムおよびロジウム錯体触媒を用いるカルボニル化反応-アリル化合物のカルボニル化およびアミンとアルコール間の交差ダブルカルボニル化-

Journal of Synthetic Organic Chemistry, Japan


N-メチルフェニルアミノホスホニウムヨージド


Rhodium Catalyzed Hydrogenation of Quinolines and Isoquinolines under Water-Gas Shift Conditions

Bulletin of the Chemical Society of Japan


Palladium(0)-Catalyzed Azidation of Allyl Esters. Selective Synthesis of Allyl Azides, Primary Allylamines, and Related Compounds


ダブルカルボニル化反応によるオキサメートの新合成法

ダブルカルボニル化反応によるオキサメートの新合成法


Palladium-catalysed Carbonylation of Allylamines

Journal of the Chemical Society. Chemical Communications


Palladium(0)-Catalyzed Carbonylation of Allyl Phosphates and Allyl Acetates. Selective Synthesis of b,g-Unsaturated Esters


Palladium(0)-Catalyzed Hydroxylamination of Allyl Esters. Synthesis of N-Allylhydroxylamines and Secondary Amines


Rhodium Catalyzed Hydrogenation of Nitrogen Heteroaromatics under Water Gas Shift Conditions. Selective Synthesis of 1,2,3,4-Tetrahydroquinolines and N-Formyl-1,2,3,4-tetrahydroisoquinolines


Palladium(0) Catalyzed Azidation and Amination of Allyl Acetaters. Selective Synthesis of Allyl Azides and Primary Allylamines


cis-Oxypalladation Complexes Derived from (1R,5R)-2(10),3-Pinadiene and Their Utilization in Pd(II)-catalyzed Enantioselective Cyclization of 2-(trans-2-Butenyl)phenols


Rhodium-Catalyzed Azacarbonylation of Allyl Phosphates. The Preparation of ,-Unsaturated Amides from Allyl Alcohols


Palladium(II)-Catalysed Oxidative Ring Cleavage of Cyclic Acetals with t-Butyl Hydroperoxide: Preparation of Monoesters of Diols


cis-Oxypalladation Complexes of a Pinene Derivative


Synthesis of blue luminescent boron complex of 3-(o-hydroxyphenyl)imidazo[1,5-a]pyridine

Proceedings of the LED General Forum 2022 Tokushima


Photodimers of symmetrical tetraaryl[3]cumulenes showing crystallization-induced emission enhancement nature


Photoinduced Asymmetric α-Oxyamination of Aldehydes Using a Flavin Catalyst and Blue LED Irradiation

Proceedings of the LED General Forum 2021


Synthesis of D-π-A Type Pyridine N-Oxides Showing Photoluminescence

Proceedings of the LED General Forum 2021 Tokushima


Fluorescent Imidazo[1,2-a]pyridinium Salt for Potent Cancer Therapeutic Agent


Synthesis of Fluorescent Chromone Derivatives and Investigation of Their Solvatofluorochromism

Proceedings of the LED General Forum 2020 Tokushima


Acid Responsive Dual Emission from Boron Complex of Imidazo[1,5-a]pyridine


Photoinduced conversion on dithioacetals into carbonyls with a flavin catalyst under blue LED irradiation

Proceedings of the LED General Forum 2019


Fluorescent N-Heteroarene as a DNA Photo-cleaving Agent under the LED Irradiation

LED総合フォーラム2019 in 徳島 論文集

LED総合フォーラム2019 in 徳島 論文集


Design of Flavin-Amine Integrated Catalysts for -Oxyamination of Aldehydes under Blue LED Irradiation

Proceedigs of the LED General Forum 2018 Tokushima


Thioacetalization of Aldehydes Using a Flavin Catalyst and Blue LED Irradiation

LED総合フォーラム2016in徳島論文集

LED総合フォーラム2016in徳島論文集


Flavin Catalysis with Photoredox Activity Under Blue LED Irradiation

LED総合フォーラム2016in徳島論文集

LED総合フォーラム2016in徳島論文集


Visible Light-Induced alfa-Oxyamination of Aldehydes with Flavin Organocatalysts

LED総合フォーラム2015 in 徳島 論文集

LED総合フォーラム2015 in 徳島 論文集


LED光を用いたフラビン触媒によるアルデヒドのチオアセタール化反応

LED光を用いたフラビン触媒によるアルデヒドのチオアセタール化反応


フラビン分子を触媒とした光レドックス反応

フラビン分子を触媒とした光レドックス反応


Improvement of chemistry laboratory class at senior high school based on continuous cooperation among high school, university and graduate school, and its application to a chemistry event for children

高大院連携化学実験の継続実施による改善と体験イベントへの活用

Journal of University Education Research


Cooperative education among high school, university and graduate school through chemestry laboratory class at senior high school

化学実験出張講義を通した高大院連携教育の試み


有機分子触媒による酸素酸化分子変換システムの開発

有機分子触媒による酸素酸化分子変換システムの開発

文部科学省科学研究費補助金「新学術研究領域」(平成23∼27年度)有機分子触媒による未来型分子変換 News Letter