Kentaro Okuma

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Organization: Faculty of Science Fukuoka University , Japan

Department: Department of Chemistry

Title: Professor(PhD)

TOPICS

Organic Chemistry

Chemicals
References

Synthesis and Fluorescence Properties of 1,1-Dimethyl-1,4-Dihydrodibenzo[b,h][1,6]naphthyridinium Iodides: Turn-on Type Detection of DNA

Co-reporter:Kentaro Okuma;Akinori Oba;Risa Kuramoto;Hidefumi Iwashita;Noriyoshi Nagahora;Kosei Shioji;Ryoma Noguchi;Masatora Fukuda

European Journal of Organic Chemistry 2017 Volume 2017(Issue 46) pp:6885-6888

Publication Date(Web):2017/12/15

DOI:10.1002/ejoc.201701277

1,4-Dihydrodibenzo[b,h][1,6]naphthyridines were synthesized by the reaction of 2-acetylaminobenzaldehyde with acetophenones in the presence of NaOH. N-Methylation of the dihydrodibenzonaphthyridines with MeI gave 1,1-dimethylammonium iodides. These salts showed UV/Vis absorbance maxima at 235 and 418 nm and very weak fluorescence at 530 nm. The fluorescence intensities were enhanced 3–10 times upon treating these salts with double-stranded DNA by intercalation, which enabled the detection of DNA/RNA by polyacrylamide gel electrophoresis (PAGE).

Tandem Reaction of Arynes with Tertiary Amines and Aldehydes: Formation of 9- and 10-Membered Dibenzo[1,5]oxaza Heterocycles

Co-reporter:Kentaro Okuma;Hiroaki Kinoshita;Noriyoshi Nagahora ;Kosei Shioji

European Journal of Organic Chemistry 2016 Volume 2016( Issue 13) pp:2264-2267

Publication Date(Web):

DOI:10.1002/ejoc.201600244

Abstract

The aryne-mediated three-component reaction of arynes, tertiary amines, and aldehydes followed by intramolecular nucleophilic aromatic substitution afforded novel 9- and 10-membered heterocycles. Thus, the reaction of 2-(trimethylsilyl)phenyl triflate with N-phenylmorpholine and benzaldehyde in the presence of CsF gave o-morpholinobenzhydryl phenyl ether in 76 % yield. By using N-methylindoline, nine-membered dibenzo[1,5]oxazonines were synthesized in moderate yields.

One-pot synthesis of dibenzo[b,h][1,6]naphthyridines from 2-acetylaminobenzaldehyde: application to a fluorescent DNA-binding compound

Co-reporter:Kentaro Okuma, Tomohiro Koga, Saori Ozaki, Yutaro Suzuki, Kenta Horigami, Noriyoshi Nagahora, Kosei Shioji, Masatora Fukuda and Masanobu Deshimaru

Chemical Communications 2014 vol. 50(Issue 98) pp:15525-15528

Publication Date(Web):23 Oct 2014

DOI:10.1039/C4CC07807A

Dibenzo[b,h][1,6]naphthyridines were synthesized in one pot by reacting 2-acetylaminobenzaldehyde with methyl ketones under basic conditions via four sequential condensation reactions. This method was also applied to the synthesis of 1,2-dihydroquinolines. 6-Methyl-1,6-dibenzonaphthyridinium triflates showed strong fluorescence, and the fluorescence intensities were changed upon intercalation into double-stranded DNA.

Reaction of Seleno- or Thiofenchone with Propiolic Acid: WagnerMeerwein Rearrangement

Co-reporter:Kentaro Okuma;Hiroyuki Matsui ;Yuichi Mori

Heteroatom Chemistry 2014 Volume 25( Issue 6) pp:578-583

Publication Date(Web):

DOI:10.1002/hc.21181

ABSTRACT

A reaction of selenofenchone with propiolic acid in refluxing chloroform produced 1,3-oxaselenin-6-one, which further reacted with acid to afford the ring-opened product. A reaction of 1,3-oxathiin-6-one prepared from thiofenchone with trifluoroacetic acid gave a Wagner–Meerwein rearranged product. In the presence of AlCl₃, thiofenchone reacted with methyl propiolate to afford the corresponding rearranged ester.

Tandem carbon–carbon bond insertion and intramolecular aldol reaction of benzyne with aroylacetones: novel formation of 4,4′-disubstituted 1,1′-binaphthols

Co-reporter:Kentaro Okuma, Ryoichi Itoyama, Ayumi Sou, Noriyoshi Nagahora and Kosei Shioj

Chemical Communications 2012 vol. 48(Issue 90) pp:11145-11147

Publication Date(Web):26 Sep 2012

DOI:10.1039/C2CC36128K

An efficient route to 4-aryl-2-naphthols from arynes and aroylacetones was developed by carbon–carbon bond insertion followed by an intramolecular aldol reaction and dehydration. Benzyne derived from 2-(trimethylsilyl)phenyl triflate reacted with benzoylacetones in refluxing acetonitrile to give 4-aryl-2-naphthols and 3-aryl-1-naphthols.

Synthesis and reaction of tricyclic tetrathiins and pentathiepins: novel formation of α-disulfines

Co-reporter:Kentaro Okuma, Kazunori Munakata, Toshiaki Tsubota, Masayuki Kanto, Noriyoshi Nagahora, Kosei Shioji, Yoshinobu Yokomori

Tetrahedron 2012 68(31) pp: 6211-6217

Publication Date(Web):

DOI:10.1016/j.tet.2012.05.069

Reaction of arynes with amino acid esters

Co-reporter:Kentaro Okuma, Nahoko Matsunaga, Noriyoshi Nagahora, Kosei Shioji and Yoshinobu Yokomori

Chemical Communications 2011 vol. 47(Issue 20) pp:5822-5824

Publication Date(Web):12 Apr 2011

DOI:10.1039/C1CC11234A

An efficient route to a variety of 2-phenylindolin-3-ones from amino acid methyl esters has been developed. The reaction of amino acid methyl esters with benzyne prepared from 2-(trimethylsilyl)phenyl triflate and CsF gave 2-phenylindolin-3-ones in moderate to good yields.

Chemoselective synthesis of quinoline N-oxides from 3-(2-nitrophenyl)-3-hydroxypropanones

Co-reporter:Kentaro Okuma;Jun-ichi Seto;Noriyoshi Nagahora ;Kosei Shioji

Journal of Heterocyclic Chemistry 2010 Volume 47( Issue 6) pp:1372-1378

Publication Date(Web):

DOI:10.1002/jhet.485

Palladium-free zinc-mediated hydroamination of alkynes: efficient synthesis of indoles from 2-akynylaniline derivatives

Co-reporter:Kentaro Okuma, Jun-ichi Seto, Ken-ichi Sakaguchi, Saori Ozaki, Noriyoshi Nagahora, Kosei Shioji

Tetrahedron Letters 2009 50(24) pp: 2943-2945

Publication Date(Web):

DOI:10.1016/j.tetlet.2009.03.210

Reaction of thioketones with propiolic acids

Co-reporter:Kentaro Okuma, Masahiro Koda, Shinobu Maekawa, Kosei Shioji, Tohru Inoue, Tsutomu Kurisaki, Hisanobu Wakita and Yoshinobu Yokomori

Organic & Biomolecular Chemistry 2006 vol. 4(Issue 14) pp:2745-2752

Publication Date(Web):12 Jun 2006

DOI:10.1039/B605068A

The reaction of adamantane-2-thione with propiolic acid afforded a novel type of cycloadduct, spiro[adamantane-2,2′-6′H-[1,3]-oxathiin]-6′-one (3a), in quantitative yield. The reaction of thiobenzophenone with propiolic acid gave 2,2-diphenyl-6′H-[1,3]-oxathiin]-6′-one and 4-phenyl-3-thia-3,4-dihydronaphthoic acid in 34% and 35% yields, respectively. The reaction might proceed through a concerted process, as confirmed by kinetics. The reaction of adamantane-2-thione with 2-butynoic acid or phenylpropiolic acid gave the corresponding adducts regioselectively. Interestingly, only one isomer was obtained by the reaction of thiofenchone with propiolic acid, suggesting that the reaction proceeded diastereospecifically. Oxidation of adducts 3 by dimethyldioxirane or m-chloroperoxybenzoic acid gave the corresponding sulfoxides and sulfones. The sulfoxides were thermally decomposed to give disulfide or another type of 1,3-oxathiin-6-one.

Synthesis and Reaction of α-Dithiolactone

Co-reporter:Toshiyuki Shigetomi;Hiroe Soejima;Yoshinori Nibu;Kosei Shioji Dr.;Yoshinobu Yokomori Dr.

Chemistry - A European Journal 2006 Volume 12(Issue 29) pp:

Publication Date(Web):3 JUL 2006

DOI:10.1002/chem.200600412

Treatment of di-tert-butylthioketene S-oxide (5 a) with Lawesson reagent at room temperature resulted in the formation of 3,3-di-tert-butylthiirane-2-thione (4 a) in high yield. The oxidation of 4 a with mCPBA (mCPBA=m-chloroperbenzioc acid) gave 3,3-di-tert-butylthiirane-2-thione S-oxide (6) almost quantitatively. The reactions of 4 a with dimethyl acetylenedicarboxylate (DMAD) and benzyne afforded dimethyl 2-(2,2,4,4-tetramethylpentan-3-ylidene)-1,3-dithiole-4,5-dicarboxylate (13) and 2-(2,2,4,4-tetramethylpentan-3-ylidene)benzo[d][1,3]dithiole (15), respectively, in high yields, suggesting that 4 a is an excellent 1,3-dipole. The reaction of 4 a with ethylenebis(triphenylphosphine)platinum (16) gave dithiolato-platinum complex (22) in high yield. The structure of 22 was determined by X-ray crystallographic analysis.

Selenobenzophenones and Diazoalkanes: Isolation of Tetraarylethylenes by the Reaction of Benzophenone Hydrazones with Diselenium Dibromide

Co-reporter:Kentaro Okuma;Kazuki Kojima;Kosuke Oyama;Kento Kubo;Kosei Shioji

European Journal of Organic Chemistry 2004 Volume 2004(Issue 4) pp:

Publication Date(Web):4 FEB 2004

DOI:10.1002/ejoc.200300510

The reaction of selenobenzophenones with diazomethane afforded the corresponding diarylethylenes and symmetrical olefins. The reaction with diaryldiazomethanes gave three different types of tetraarylethylenes. This reaction proceeded through 1,3,4-selenadiazoline intermediates, and retrocyclization was observed. The formation of 1,3,4-selendiazolines was independently confirmed by the reaction of benzophenone hydrazones with diselenium dibromide, which afforded tetraarylethylenes in good yields. This method is applicable to the two-step synthesis of tetraarylethylenes from benzophenones. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

First Isolation of Thione-Propiolic Acid Adducts − Synthesis of Thiodioxenones

Co-reporter:Kentaro Okuma;Shinobu Maekawa;Shinji Shibata;Kosei Shioji;Thoru Inoue;Tsutomu Kurisaki;Hisanobu Wakita;Yoshinobu Yokomori

European Journal of Organic Chemistry 2003 Volume 2003(Issue 19) pp:

Publication Date(Web):16 SEP 2003

DOI:10.1002/ejoc.200300300

Treatment of adamantane-2-thione (1a) with propiolic acid (2a) afforded a novel type of cycloadduct, spiro[adamantane-2,2′-[1,3]oxathiin]-6-one (3a), in quantitative yield. The reaction proceeds through a concerted process, as was confirmed by kinetic analysis. Treatment of 1a with butynoic acid or phenylpropiolic acid gave the corresponding adducts regioselectively. Interestingly, only one isomer was obtained by treatment of thiofenchone with propiolic acid, suggesting that the reaction proceeded stereospecifically. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Unusual formation of a thiacyclopent-2-ene by the reaction of 4,4′-dimethoxythiobenzophenone with tetracyanoethylene

Co-reporter:Yoshikazu Tsujimoto

Heteroatom Chemistry 2001 Volume 12(Issue 4) pp:259-262

Publication Date(Web):30 MAY 2001

DOI:10.1002/hc.1041

The reaction of 4,4′-dimethoxythiobenzophenone (1a) with tetracyanoethylene (TCNE) afforded an unusual type of 2:1 adduct with the structure of thiacyclopent-2-ene (5a). On the other hand, the reaction of thiobenzophenone (1b) with TCNE afforded the corresponding thiophene, the normal 2:1 adduct (2b). The mechanism of the formation of 5a is discussed. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:259–262, 2001

A new simple synthesis of cis- and trans-3,5-di-tert-butyl-3,5-diaryl-1,2,4-trithiolanes from ketones and tetraphosphorus decasulfide

Co-reporter:Kentaro Okuma, Shinji Shibata, Kosei Shioji and Yoshinobu Yokomori

Chemical Communications 2000 (Issue 16) pp:1535-1536

Publication Date(Web):25 Jul 2000

DOI:10.1039/B004013O

The reaction of pivalophenones with tetraphosphorus decasulfide afforded cis- and trans-3,5-di-tert-butyl-3,5-diaryl-1,2,4-trithiolanes, which equilibrated to give other isomers in refluxing toluene via thiopivalophenones and thiopivalophenone S-sulfides.

Tandem carbon–carbon bond insertion and intramolecular aldol reaction of benzyne with aroylacetones: novel formation of 4,4′-disubstituted 1,1′-binaphthols

Co-reporter:Kentaro Okuma, Ryoichi Itoyama, Ayumi Sou, Noriyoshi Nagahora and Kosei Shioj

Chemical Communications 2012 - vol. 48(Issue 90) pp:NaN11147-11147

Publication Date(Web):2012/09/26

DOI:10.1039/C2CC36128K

One-pot synthesis of dibenzo[b,h][1,6]naphthyridines from 2-acetylaminobenzaldehyde: application to a fluorescent DNA-binding compound

Co-reporter:Kentaro Okuma, Tomohiro Koga, Saori Ozaki, Yutaro Suzuki, Kenta Horigami, Noriyoshi Nagahora, Kosei Shioji, Masatora Fukuda and Masanobu Deshimaru

Chemical Communications 2014 - vol. 50(Issue 98) pp:NaN15528-15528

Publication Date(Web):2014/10/23

DOI:10.1039/C4CC07807A

Reaction of arynes with amino acid esters

Co-reporter:Kentaro Okuma, Nahoko Matsunaga, Noriyoshi Nagahora, Kosei Shioji and Yoshinobu Yokomori

Chemical Communications 2011 - vol. 47(Issue 20) pp:NaN5824-5824

Publication Date(Web):2011/04/12

DOI:10.1039/C1CC11234A