Nagatoshi Nishiwaki

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Organization: Kochi University of Technology

Department: School of Environmental Science and Engineering

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Polymer

Polyurethane

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References

Synthesis of Functionalized 3-Cyanoisoxazoles Using a Dianionic Reagent

Co-reporter:Kento Iwai, Haruyasu Asahara, and Nagatoshi Nishiwaki

The Journal of Organic Chemistry May 19, 2017 Volume 82(Issue 10) pp:5409-5409

Publication Date(Web):May 4, 2017

DOI:10.1021/acs.joc.7b00811

A series of 5-acylated 3-cyanoisoxazoles were efficiently synthesized by the Michael addition of dianionic cyano-aci-nitroacetate to α-chloro-α,β-unsaturated ketones followed by intramolecular nucleophilic substitution of the nitronate ion intermediate. In this process, the dianionic reagent serves as the safe synthetic equivalent of the explosive nitroacetonitrile. The 3-cyano group is sufficiently reactive toward ethanolysis and 1,3-dipolar cycloaddition with an azide to afford ethyl ester and tetrazole, respectively. A pyridine ring between the 5-acyl and the 4-aryl group was also constructed. This led to the formation of the isoxazolo[5,4-c]quinoline derivative.

Hydrohalogenation of Ethynylpyridines Involving Nucleophilic Attack of a Halide Ion

Co-reporter:Kengo Muragishi, Haruyasu Asahara, and Nagatoshi Nishiwaki

ACS Omega April 2017? Volume 2(Issue 4) pp:1265-1265

Publication Date(Web):April 4, 2017

DOI:10.1021/acsomega.7b00133

Efficient hydrochlorination of 2-ethynylpyridines was achieved without the use of special reagents. Ethynylpyridine readily reacts with hydrochloric acid to form a pyridinium salt. The salt formation considerably enhances the electrophilicity of the ethynyl group and attracts a chloride ion as the counteranion. The spatial proximity facilitates the nucleophilic addition of the halide anion to the ethynyl group, producing 2-(2-chloroethenyl)pyridine in high yields. This protocol could also be applied for hydrobromination and hydroiodination using hydrobromic and hydroiodic acids, respectively. In the case of acetic acid, the reaction did not proceed because of the low acidity and lack of salt formation. This problem was overcome by exchanging the counteranion using silver acetate; the resultant pyridinium acetate underwent hydroacetoxylation.

Synthesis of functionalized 4-nitroanilines by ring transformation of dinitropyridone with enaminones

Co-reporter:Saki Naito, Soichi Yokoyama, Haruyasu Asahara, Nagatoshi Nishiwaki

Tetrahedron Letters 2017 Volume 58, Issue 50(Issue 50) pp:

Publication Date(Web):13 December 2017

DOI:10.1016/j.tetlet.2017.11.003

•A new synthetic method for functionalized nitroanilines was provided.•Ring transformation of dinitropyridone with enaminone efficiently proceeded.•The amino group could be easily modified.•Several functional groups could be introduced into the 4-nitroaniline framework.2-Functionalized 4-nitroanilines were readily synthesized by ring transformation using 3,5-dinitro-2-pyridone and enaminones prepared from 1,3-dicarbonyl compounds and amines. Modification of the amino group and the ortho-position could be achieved by simply changing the enaminones. Using this strategy, functional groups such as acetyl, benzoyl, and ethoxycarbonyl groups could be introduced into the nitroaniline framework.Download high-res image (44KB)Download full-size image

Tailor-made synthesis of fully alkylated/arylated nicotinates by FeCl3-mediated condensation of enamino esters with enones

Co-reporter:Sho Hirai;Yurie Horikawa;Haruyasu Asahara

Chemical Communications 2017 vol. 53(Issue 15) pp:2390-2393

Publication Date(Web):2017/02/16

DOI:10.1039/C7CC00051K

A new method for synthesizing polyalkylated/arylated nicotinates is established using a condensation of enamino esters with enones in the presence of FeCl3. This method facilitates the introduction of alkyl or aryl groups at any position on demand, which has not been achieved by other procedures.

A direct and vicinal functionalization of the 1-methyl-2-quinolone framework: 4-alkoxylation and 3-chlorination

Co-reporter:Feiyue Hao, Haruyasu Asahara and Nagatoshi Nishiwaki

Organic & Biomolecular Chemistry 2016 vol. 14(Issue 22) pp:5128-5135

Publication Date(Web):06 May 2016

DOI:10.1039/C6OB00868B

Bis(functionalization), 4-alkoxylation and 3-chlorination, of the 1-methyl-2-quinolone framework was achieved under mild conditions by a sequential treatment of 3-nitrated 1-methyl-2-quinolones with sodium alkoxide and N-chlorosuccinimide. Moreover, a succinimide group instead of an alkoxy group was introduced at the 4-position, affording a masked form of the 4-amino-3-chloro-2-quinolone derivative. Furthermore, the prepared vicinally functionalized quinolones thus obtained were subjected to a Suzuki–Miyaura coupling reaction, arylating the 3-position.

Acid promoted dimerization of β-amino-α,β-unsaturated amides affording bis(functionalized) pyrrolinones

Co-reporter:Sho Hirai, Haruyasu Asahara, Nagatoshi Nishiwaki

Tetrahedron Letters 2016 Volume 57(Issue 52) pp:5896-5898

Publication Date(Web):28 December 2016

DOI:10.1016/j.tetlet.2016.11.068

•A practically usable synthetic method for pyrrolinones was established.•Acid promoted dimerization of 3-amino-2-butenamides efficiently proceeded.•Air oxidation and 1,2-migration of the methyl group were accompanied.•The substituents are easily modified by simply changing the enamides.Polysubstituted pyrrolinones were synthesized by the dimerization of 3-amino-2-butenamides via treatment with 0.5 equiv p-TsOH under mild reaction conditions, including oxidation and 1,2-migration of the methyl group. This method is practically advantageous compared to the conventional methods for the preparation of pyrrolinones, because it does not require difficult experimental manipulations and special reagents such as metal catalysts and oxidants. Because the structures of β-amino-α,β-unsaturated amides can be easily modified by changing the precursors, β-keto amide and amine, synthesis of diverse pyrrolinones is possible.

Tailor-Made Synthesis of N,N,2,6-Tetrasubstituted 4-Nitroanilines by Three-Component Ring Transformation of Dinitropyridone

Co-reporter:Song Thi Le;Haruyasu Asahara

European Journal of Organic Chemistry 2015 Volume 2015( Issue 6) pp:1203-1206

Publication Date(Web):

DOI:10.1002/ejoc.201403652

Abstract

The ring transformation of dinitropyridone afforded various kinds of 2,6-disubstituted-4-nitroanilines upon treatment with aliphatic ketones in the presence of ammonium acetate as a nitrogen source, wherein dinitropyridone behaved as the synthetic equivalent of unstable nitromalonaldehyde. The benzene ring, as well as the amino group of the nitroaniline framework, was easily modified by only changing a ketone and the nitrogen source, which afforded N,N,2,6-tetrasubstituted 4-nitroanilines in good to excellent yields.

Functionalization of a Pyridine Framework through Intramolecular ReissertHenze Reaction of N-(Carbamoyloxy)pyridinium Salts and Unexpected Insertion of Ethereal Solvents

Co-reporter:Haruyasu Asahara;Asuka Kataoka;Shotaro Hirao

European Journal of Organic Chemistry 2015 Volume 2015( Issue 18) pp:3994-3999

Publication Date(Web):

DOI:10.1002/ejoc.201500443

Abstract

A new strategy for synthesis of the 2-pyridyl carbamates is reported. This strategy exploits a new intramolecular transformation of an acyloxy group from N-carbamoyloxypyridinium salts (Reissert–Henze-type reaction) as the key step. Addition of a silver salt effectively accelerates the intramolecular attack of the carbonyl oxygen at the 2-position of the pyridine ring. Additionally, a new rearrangement of the acyloxy group, combined with insertion of an ethereal solvent to give pyridine derivatives having a coordinating tether, is reported.

Development of a new palladium catalyst supported on phenolic resin

Co-reporter:Nagatoshi Nishiwaki, Sayaka Hamada, Tomoe Watanabe, Shotaro Hirao, Jun Sawayama, Haruyasu Asahara, Kazuhiko Saigo, Toru Kamata and Masahiko Funabashi

RSC Advances 2015 vol. 5(Issue 6) pp:4463-4467

Publication Date(Web):08 Dec 2014

DOI:10.1039/C4RA14346A

A phenolic resin-supported palladium catalyst, in which hydroxyl groups contribute to the stabilization of palladium nanoparticles, was developed. The catalyst could be used repeatedly, and thus has a large turn over number (TON). When a composite of polyethylene terephthalate and phenolic resin was employed as a support, the catalyst was easily deformed on demand.

Construction of 3,5-dinitrated 1,4-dihydropyridines modifiable at 1,4-positions by a reaction of β-formyl-β-nitroenamines with aldehydes

Co-reporter:Haruyasu Asahara, Mai Hamada, Yumi Nakaike and Nagatoshi Nishiwaki

RSC Advances 2015 vol. 5(Issue 110) pp:90778-90784

Publication Date(Web):16 Oct 2015

DOI:10.1039/C5RA19439C

A novel and efficient method for the synthesis of 4-substituted 3,5-dinitro-1,4-dihydropyridines by a reaction of β-formyl-β-nitroenamines with aldehydes was developed. The reaction of nitroenamines with aldehydes leading to 1,4-dihydropyridines and the self-condensation of nitroenamines leading to pyridinium salt intermediate proceed competitively. The obtained 3,4,5-trisubstituted-1,4-dihydropyridines readily transformed into the corresponding pyridines in high yields.

Synthesis of diazabicyclo compounds possessing an α-nitrolactam framework

Co-reporter:Haruyasu Asahara, Shota Takeda, Kazuhiko Saigo, Nagatoshi Nishiwaki

Tetrahedron Letters 2015 Volume 56(Issue 19) pp:2504-2507

Publication Date(Web):6 May 2015

DOI:10.1016/j.tetlet.2015.03.100

Diazabicyclo compounds possessing an α-nitrolactam framework were directly synthesized upon treatment of α-nitro-δ-keto esters with diamines. This reaction proceeds via pseudo-intramolecular process. In this process, the formation of ammonium nitronate is a key step, by which the amino group and the ketone carbonyl group are in close proximity to cause the imine formation efficiently. The following tandem bicyclization constructs 1,7-diaza-3-nitro-2-oxobicyclic systems having two aryl groups at the 4- and 6-positions.

An Alternative Synthetic Approach to 3-Alkylated/Arylated 5-Nitropyridines

Co-reporter:Song Thi Le, Haruyasu Asahara, and Nagatoshi Nishiwaki

The Journal of Organic Chemistry 2015 Volume 80(Issue 17) pp:8856-8858

Publication Date(Web):August 5, 2015

DOI:10.1021/acs.joc.5b01391

An alternative method for the synthesis of 3-alkylated/arylated 5-nitropyridines was developed involving a three-component ring transformation of 3,5-dinitro-2-pyridone on treatment with aldehyde in the presence of ammonium acetate. This method facilitates the modification of the substituent at the 3-position by changing the precursor aldehyde. The use of solid ammonium acetate instead of ammonia as the nitrogen source renders the synthetic method more practical and user-friendly.

Corrigendum to “Safe cyano(nitro)methylating reagent—Michael addition of cyano-aci-nitroacetate leading to δ-functionalized α-nitronitriles” [Tetrahedron 70 (2014) 6522–6528]

Co-reporter:Haruyasu Asahara, Kyo Muto, Nagatoshi Nishiwaki

Tetrahedron 2015 Volume 71(Issue 32) pp:5159

Publication Date(Web):12 August 2015

DOI:10.1016/j.tet.2015.06.009

An NMR study on a pseudo-intramolecular transacylation reaction of an α-aryl-β-keto ester

Co-reporter:Sho Hirai, Haruyasu Asahara, Shotaro Hirao, Jun Sawayama, Ryuichi Sugimoto, Kazuhiko Saigo and Nagatoshi Nishiwaki

RSC Advances 2014 vol. 4(Issue 10) pp:4889-4892

Publication Date(Web):14 Nov 2013

DOI:10.1039/C3RA45568H

The pseudo-intramolecular transacylation reaction efficiently proceeds like an intramolecular reaction, even though it is actually an intermolecular reaction. We have obtained valuable insights by monitoring the reaction by 1H NMR spectroscopy.

Synthesis of 2-Aryl-5-Nitropyridines by Three-Component Ring Transformation of 3,5-Dinitro-2-Pyridone

Co-reporter:Thi Song Le;Dr. Haruyasu Asahara; Kazuya Kobiro; Ryuichi Sugimoto; Kazuhiko Saigo ; Nagatoshi Nishiwaki

Asian Journal of Organic Chemistry 2014 Volume 3( Issue 3) pp:297-302

Publication Date(Web):

DOI:10.1002/ajoc.201300282

Abstract

2-Arylated-5-nitropyridines were efficiently synthesized by a three-component ring transformation of 3,5-dinitro-2-pyridone with aromatic ketones in the presence of ammonium acetate, in which the dinitropyridone serves as a synthetic equivalent of an unstable nitromalonaldehyde. Although a 2,8-diazabicyclo[3.3.1]non-3-ene derivative was also formed as a byproduct, it was converted into nitropyridines under the reaction conditions, heating in the presence of ammonium acetate. This experimental fact implies that the former compound is a kinetically controlled product and the latter is a thermodynamically controlled product because of the aromatization. This method is applicable to various kinds of aryl and (hetero)aryl ketones to afford the corresponding (hetero)arylated pyridines in good to excellent yields.

Facilitation of the reduction of Pd(II) by the glass surface – Development of a glass-supported palladium catalyst

Co-reporter:Nagatoshi Nishiwaki, Yasuyuki Mori, Erina Fukuoka, Haruyasu Asahara, Shotaro Hirao, Jun Sawayama, Kazuhiko Saigo, Tomoya Konishi, Masahiko Shimoda

Chemical Physics Letters 2014 Volume 608() pp:340-343

Publication Date(Web):21 July 2014

DOI:10.1016/j.cplett.2014.06.005

Metal-Free α-Hydroxylation of α-Unsubstituted β-Oxoesters and β-Oxoamides

Co-reporter:Haruyasu Asahara and Nagatoshi Nishiwaki

The Journal of Organic Chemistry 2014 Volume 79(Issue 23) pp:11735-11739

Publication Date(Web):November 7, 2014

DOI:10.1021/jo501985u

A direct metal-free α-hydroxylation of α-unsubstituted β-oxoesters and β-oxoamides was developed using m-chloroperbenzoic acid as the oxidant. This transformation enabled straightforward metal-free access to important α-hydroxy-β-dicarbonyl moieties under mild reaction conditions. Furthermore, the hydroxylated products were readily converted into vicinal tricarbonyl compounds, which are useful synthetic precursors of numerous biological targets.

Synthesis of 4-Substituted 3,5-Dinitro-1,4-dihydropyridines by the Self-Condensation of β-Formyl-β-nitroenamine

Co-reporter:Yumi Nakaike, Nagatoshi Nishiwaki, Masahiro Ariga, and Yoshito Tobe

The Journal of Organic Chemistry 2014 Volume 79(Issue 5) pp:2163-2169

Publication Date(Web):February 5, 2014

DOI:10.1021/jo5000187

3,5-Dinitro-1,4-dihydropyridines (DNDHPs) are readily constructed by the acid-promoted self-condensation of β-formyl-β-nitroenamines. In the DNDHPs, one molecule of the nitroenamine serves as a C3N1 building block and the other serves as a C2 block. This synthetic method does not require any special reagents and conditions. When the reaction is conducted in the presence of electron-rich benzene derivatives, arylation at the 4-position of DNDHP is achieved by trapping the 3,5-dinitropyridinium ion intermediate.

Safe cyano(nitro)methylating reagent—Michael addition of cyano-aci-nitroacetate leading to δ-functionalized α-nitronitriles

Co-reporter:Haruyasu Asahrara, Kyo Muto, Nagatoshi Nishiwaki

Tetrahedron 2014 70(37) pp: 6522-6528

Publication Date(Web):

DOI:10.1016/j.tet.2014.07.013

Synthesis of vicinally functionalized 1,4-dihydropyridines and diazabicycles via a pseudo-intramolecular process

Co-reporter:Nagatoshi Nishiwaki, Shotaro Hirao, Jun Sawayama, Haruyasu Asahara, Ryuichi Sugimoto, Kazuya Kobiro, Kazuhiko Saigo

Tetrahedron 2014 70(2) pp: 402-408

Publication Date(Web):

DOI:10.1016/j.tet.2013.11.044

Mechanistic aspect of ring transformations in the reaction of 5-nitro-4-pyrimidinone with acetophenone derivatives and cycloalkanones depending on the electron density/ring size of the ketone

Co-reporter:Nagatoshi Nishiwaki, Ryuichi Sugimoto, Kazuhiko Saigo, Kazuya Kobiro

Tetrahedron Letters 2013 Volume 54(Issue 8) pp:956-959

Publication Date(Web):20 February 2013

DOI:10.1016/j.tetlet.2012.12.020

3-Methyl-5-nitro-4-pyrimidinone undergoes two kinds of nucleophilic type ring transformations upon treatment with cycloalkanones in the presence of ammonium acetate, which affords 4,5-disubstituted pyrimidines and 5,6-disubstituted 3-nitro-2-pyridones. In order to improve the synthetic utility of this reaction, it is necessary to control the regioselectivity of these ring transformations. In the present work, we performed DFT calculation to realize the selectivity of two ring transformation products. In cases of adduct intermediates derived from cyclohexanone and cyclooctanone, the 2-attack proceeds preferably to give condensed pyrimidines. On the other hand, the adduct intermediate derived from cycloheptanone undergoes the 4-attack predominantly to afford condensed nitropyridone.

Reactive 2-quinolones dearomatized by steric repulsion between 1-methyl and 8-substituted groups

Co-reporter:Xin Chen, Kazuya Kobiro, Haruyasu Asahara, Kiyomi Kakiuchi, Ryuichi Sugimoto, Kazuhiko Saigo, Nagatoshi Nishiwaki

Tetrahedron 2013 69(23) pp: 4624-4630

Publication Date(Web):

DOI:10.1016/j.tet.2013.04.008

Hydroxylated surface of GaAs as a scaffold for a heterogeneous Pd catalyst

Co-reporter:Nagatoshi Nishiwaki, Tomoya Konishi, Shotaro Hirao, Yoshiyuki Yamashita, Hideki Yoshikawa and Masahiko Shimoda

Physical Chemistry Chemical Physics 2012 vol. 14(Issue 4) pp:1424-1430

Publication Date(Web):07 Dec 2011

DOI:10.1039/C1CP22537E

A novel use of GaAs, namely, as a scaffold for a heterogeneous palladium catalyst, is proposed. Hydroxy groups on the GaAs surface play important roles. During the adsorption of Pd(OAc)2 on the GaAs surface, the hydroxy groups attract Pd(II) species by anion exchange. A subsequent redox reaction proceeds to generate Pd(0) nanoparticles, which are stabilized on the GaAs surface. This process is confirmed by surface-sensitive measurements: diffuse reflection IR spectroscopy and X-ray photoelectron spectroscopy. Moreover, a more bulk-sensitive measurement, hard X-ray photoemission spectroscopy with synchrotron radiation, also supported our considerations. The amounts of Pd(0) nanoparticles on the surface were evaluated by catalytic activity, yield, and recyclability in the Heck reaction, in addition to the deposit test.

One-step synthesis of differently bis-functionalized isoxazoles by cycloaddition of carbamoylnitrile oxide with β-keto esters

Co-reporter:Nagatoshi Nishiwaki, Kazuya Kobiro, Shotaro Hirao, Jun Sawayama, Kazuhiko Saigo, Yumiko Ise, Maho Nishizawa and Masahiro Ariga

Organic & Biomolecular Chemistry 2012 vol. 10(Issue 10) pp:1987-1991

Publication Date(Web):27 Jan 2012

DOI:10.1039/C2OB06925C

A new protocol for synthesizing different functionalized isoxazoles is provided. Carbamoylnitrile oxide generated from nitroisoxazolone underwent inverse electron-demand 1,3-dipolar cycloaddition with 1,3-dicarbonyl compounds in the presence of magnesium acetate that formed magnesium enolatein situ. Although electron-deficient trifluoroacetoacetate did not undergo this cycloaddition under the same conditions, conversion to sodium enolate furnish the corresponding bis-functionalized trifluoromethylisoxazole. The DFT calculations using B3LYP 6-31G+(d,p) also supported the aforementioned reactivity.

Ring construction via pseudo-intramolecular hydrazonation using bifunctional δ-keto nitrile

Co-reporter:Shotaro Hirao, Kazuya Kobiro, Jun Sawayama, Kazuhiko Saigo, Nagatoshi Nishiwaki

Tetrahedron Letters 2012 Volume 53(Issue 1) pp:82-85

Publication Date(Web):4 January 2012

DOI:10.1016/j.tetlet.2011.10.159

An α-nitro-δ-keto nitrile efficiently reacted with hydrazines at room temperature, even in the absence of a catalyst, to afford the corresponding hydrazones; the reactions proceeded through a pseudo-intramolecular process. The hydrazone derived from hydrazine monohydrate underwent water-assisted cyclization, which yielded the corresponding diazepine. The hydrazones derived from 4-nitrophenylhydrazine and 2,4-dinitrophenylhydrazine were converted into pyridazines upon being heated in DMSO.

An anomalous hydration/dehydration sequence for the mild generation of a nitrile oxide

Co-reporter:Nagatoshi Nishiwaki, Kazuya Kobiro, Hideyuki Kiyoto, Shotaro Hirao, Jun Sawayama, Kazuhiko Saigo, Yoshikazu Okajima, Toshiharu Uehara, Asaka Maki and Masahiro Ariga

Organic & Biomolecular Chemistry 2011 vol. 9(Issue 8) pp:2832-2839

Publication Date(Web):13 Jan 2011

DOI:10.1039/C0OB01005G

A nitrile oxide containing a carbamoyl group is readily generated upon the treatment of 2-methyl-4-nitro-3-isoxazolin-5(2H)-one with water under mild reaction conditions, even in the absence of special reagents. The obtained nitrile oxide undergoes cycloaddition with dipolarophiles, alkynes and alkenes, to afford the corresponding isoxazol(in)es, which are useful intermediates in the synthesis of polyfunctionalized compounds. A plausible mechanism underlying the formation of the nitrile oxide is proposed, which involves an anomalous hydration/dehydration sequence. DFT calculations were also performed to support this mechanism.

Inverse electron-demand 1,3-dipolar cycloaddition of nitrile oxide with common nitriles leading to 3-functionalized 1,2,4-oxadiazoles

Co-reporter:Nagatoshi Nishiwaki, Kazuya Kobiro, Shotaro Hirao, Jun Sawayama, Kazuhiko Saigo, Yumiko Ise, Yoshikazu Okajima and Masahiro Ariga

Organic & Biomolecular Chemistry 2011 vol. 9(Issue 19) pp:6750-6754

Publication Date(Web):29 Jun 2011

DOI:10.1039/C1OB05682D

A carbamoyl-substituted nitrile oxide was generated upon treatment of easily available 2-methyl-4-nitro-3-isoxazolin-5(2H)-one with THF (not dried); the reaction proceeded efficiently even in the absence of any special reagents and reaction conditions. The nitrile oxide caused 1,3-dipolar cycloaddition with common aliphatic nitriles or electron-rich aromatic nitriles to afford 3-functionalized 1,2,4-oxadiazoles, which are expected to serve as precursors for the preparation of a variety of functional materials by the chemical transformation of the carbamoyl group. While conventional preparative methods for 1,2,4-oxadiazoles involve the cycloaddition of an electron-rich nitrile oxide with an electron-deficient nitrile or a nitrile activated by a Lewis acid, our method employs the complementary combination of an electron-rich nitrile and an electron-deficient nitrile oxide- the inverse electron-demand 1,3-cycloaddition. The DFT calculations using B3LYP 6-31G* supported the abovementioned inverse reactivity, and also suggested the presence of an accelerating effect by the carbamoyl group as a result of hydrogen bond formation with a dipolarophilic nitrile.

Efficient double bond migration of allylbenzenes catalyzed by Pd(OAc)2–HFIP system with unique substituent effect

Co-reporter:Nagatoshi Nishiwaki, Ryuichiro Kamimura, Kimihiro Shono, Toshihiko Kawakami, Katsuhisa Nakayama, Kohei Nishino, Takayuki Nakayama, Keisuke Takahashi, Aki Nakamura, Takahiro Hosokawa

Tetrahedron Letters 2010 Volume 51(Issue 27) pp:3590-3592

Publication Date(Web):7 July 2010

DOI:10.1016/j.tetlet.2010.05.014

A novel catalyst system of Pd(OAc)2–HFIP induces double-bond migration of allylbenzenes under mild conditions with low catalytic loading to afford 1-propenylbenzenes. The reaction shows a unique substituent effect that is highly dependent on the distance of substituents from the allylic moiety. Thus, the reactivity of substrates bearing a methyl group is ordered in para > meta > ortho, whereas it is entirely reversed as ortho > meta > para for methoxy and chloro substituents.

Direct amino-halogenation and aziridination of the 2-quinolone framework by sequential treatment of 3-nitro-2-quinolone with amine and N-halosuccinimide

Co-reporter:Feiyue Hao, Haruyasu Asahara, Nagatoshi Nishiwaki

Tetrahedron (2 March 2017) Volume 73(Issue 9) pp:

Publication Date(Web):2 March 2017

DOI:10.1016/j.tet.2017.01.028

The sequential treatment of 3-nitro-2-quinolones with amines and N-halosuccinimides under mild conditions facilitated the direct amino-halogenation and aziridination at the 4- and 3-positions of the 2-quinolone framework. The selectivity of the functionalization was influenced by the electronic properties of the substituents on the benzene moiety of the nitroquinolone. The electron-withdrawing nitro group promoted the amino-halogenation, and replacement of the nitro group with a halogen or hydrogen markedly increased the selectivity of the aziridination. Moreover, a succinimide group instead of an alkylamino group was introduced at the 4-position, affording the masked form of the 4-amino-3-chloro-2-quinolone derivative. Furthermore, the prepared bis-functionalized quinolones were subjected to Suzuki-Miyaura coupling reaction, ring opening, and hydrazinolysis to afford differently functionalized quinolones.

Tailor-made synthesis of fully alkylated/arylated nicotinates by FeCl3-mediated condensation of enamino esters with enones

Co-reporter:Sho Hirai, Yurie Horikawa, Haruyasu Asahara and Nagatoshi Nishiwaki

Chemical Communications 2017 - vol. 53(Issue 15) pp:NaN2393-2393

Publication Date(Web):2017/02/03

DOI:10.1039/C7CC00051K

An anomalous hydration/dehydration sequence for the mild generation of a nitrile oxide

Co-reporter:Nagatoshi Nishiwaki, Kazuya Kobiro, Hideyuki Kiyoto, Shotaro Hirao, Jun Sawayama, Kazuhiko Saigo, Yoshikazu Okajima, Toshiharu Uehara, Asaka Maki and Masahiro Ariga

Organic & Biomolecular Chemistry 2011 - vol. 9(Issue 8) pp:NaN2839-2839

Publication Date(Web):2011/01/13

DOI:10.1039/C0OB01005G

Inverse electron-demand 1,3-dipolar cycloaddition of nitrile oxide with common nitriles leading to 3-functionalized 1,2,4-oxadiazoles

Co-reporter:Nagatoshi Nishiwaki, Kazuya Kobiro, Shotaro Hirao, Jun Sawayama, Kazuhiko Saigo, Yumiko Ise, Yoshikazu Okajima and Masahiro Ariga

Organic & Biomolecular Chemistry 2011 - vol. 9(Issue 19) pp:NaN6754-6754

Publication Date(Web):2011/06/29

DOI:10.1039/C1OB05682D

One-step synthesis of differently bis-functionalized isoxazoles by cycloaddition of carbamoylnitrile oxide with β-keto esters

Co-reporter:Nagatoshi Nishiwaki, Kazuya Kobiro, Shotaro Hirao, Jun Sawayama, Kazuhiko Saigo, Yumiko Ise, Maho Nishizawa and Masahiro Ariga

Organic & Biomolecular Chemistry 2012 - vol. 10(Issue 10) pp:NaN1991-1991

Publication Date(Web):2012/01/27