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発表論文

Published in 2014

chemsci
Sunlight photocatalyzed regioselective β-alkylation and acylation of cyclopentanones
Megumi Okada, Takahide Fukuyama, Keiichi Yamada, Ilhyong Ryu, Davide Ravelli, Maurizio Fagnoni
Chem. Sci, 2014, 5, 7 pp. 2893 - 2898
DOI: 10.1039/C4SC01072H
6
Sunlight-induced direct regioselective β-alkylation of cyclopentanones with electron-deficient alkenes was accomplished by using tetrabutylammonium decatungstate (TBADT) as the catalyst. The regiochemistry can be rationalized by a polar transition state for an SH2 reaction. In the presence of CO, the reaction gave the three-component β-acylation product in good yield.

chemistry-AEur
Revisiting the Bromination of C[BOND]H Bonds with Molecular Bromine by Using a Photo-Microflow System
Yoshiyuki Manabe, Yuriko Kitawaki, Masahiro Nagasaki, Koichi Fukase, Hiroshi Matsubara, Yoshiko Hino, Takahide Fukuyama, Ilhyong Ryu
Chem. Eur. J., 2014, 20, 40 pp. 12750 - 12753
DOI: 10.1002/chem.201402303
image_n_nsch001
  The photobromination of C[BOND]H bonds by using molecular bromine was reinvestigated under microfluidic conditions. The continuous-flow method suppressed the production of dibrominated compounds and effectively produced the desired monobrominated products with high selectivity. Rapid bromination of benzylic substrates containing a photoaffinity azide group was achieved without any decomposition.

Org. Chem. Front.
Radical vinylation of dioxolanes and N-acylpyrrolidines using vinyl bromides
Takashi Kippo, Yuki Kimura, Ayami Maeda, Hiroshi Matsubara, Takahide Fukuyama, Ilhyong Ryu
Org. Chem. Front., 2014, 1, 7 pp. 755 - 758
DOI: 10.1039/C4QO00138A
5
Radical vinylation was investigated using vinyl bromides with an electron-withdrawing substituent at the β-position. The vinylation of 1,3-dioxolanes proceeded well to give 2-vinyl-1,3-dioxolanes in good yields. The α-vinylation of N-acylpyrrolidines also proceeded well to give 2-vinyl-N-acylpyrrolidines.

orgbiomolchem
Radical reactions of borohydrides
Takuji Kawamoto, Ilhyong Ryu
Org. Biomol. Chem., 2014, 12, 48 pp. 9733 - 9742
DOI: 10.1039/C4OB01784F
4
Borohydrides are an important class of reagents in both organic and inorganic chemistry. Though popular as hydride-transfer reagents for reduction, since earlier work from the 1970s, borohydride reagents have also been known to serve as hydrogen-transfer reagents. In pursuit of greener tin hydride substitutes, recent progress has been made to mediate radical C–C bond forming reactions, including Giese reactions, radical carbonylation and addition to HCHO reactions, with borohydride reagents. This review article focuses on state-of-the-art borohydride based radical reactions, also covering earlier work, kinetics and some DFT calculations with respect to the hydrogen transfer mechanism.

Organic Letters
Flow Update for the Carbonylation of 1-Silyl-Substituted Organolithiums under CO Pressure
Takahide Fukuyama, Takenori Totoki, Ilhyong Ryu
Org. Lett., 2014, 16, 21 pp. 5632 - 5635
DOI: 10.1021/ol5026958
3
The generation of, and subsequent reactions with, 1-silyl-substituted organolithiums with CO was carried out using serially connected flow microreactors. The flow system proved to be quite useful for the carbonylation of silyl-substituted organolithiums under slightly pressurized conditions of CO, which was created conveniently by the use of a back-pressure regulator. This flow system, coupled with heating, accelerated the carbonylation reaction of 1-silyl-substituted organolithiums and allowed the stable silyl-substituted alkyllithium, 1,3-disilylallyllithium, which was not effective in a batch-flask reaction under a CO atmosphere, to participate in an efficient carbonylation reaction.

Flow Carbonylation Using Near-stoichiometric Carbon Monoxide. Application to Heck Carbonylation
Hiromichi Akinaga, Naoki Masaoka, Kazuhiro Takagi, Ilhyong Ryu, Takahide Fukuyama
Chem.Lett., 2014, 43, 9 pp. 1456 - 1458
DOI: 10.1246/cl.140415
2

The Heck carbonylation of 1-bromo-3,5-bis(trifluoromethyl)benzene in methanol was successfully carried out by using a stainless steel tubular flow reactor with near-stoichiometric amounts of CO. Continuous flow experiment using a larger tubular reactor was also was successful, which allows for kilogram order of methyl ester of the aromatic carboxylic acid.  

Chem._Lett._
A Theoretical Study on Reduction of Acyl Radicals with Borohydride Anions
Takuji Kawamoto, Hiroshi Matsubara, Ilhyong Ryu
Chem.Lett., 2014, 43, 7 pp. 1140 - 1142
DOI: 10.1246/cl.140370
CL-140370figc
Ab initio and DFT calculations predict that the reduction of acetyl radical with borohydride proceeds via hydride attack at the carbonyl carbon to afford the ketyl radical.

Org. Lett
Cyanoborohydride-Promoted Radical Arylation of Benzene
Kawamoto, T., Sato, A., Ryu, I.
Org. Lett., 2014, 16, 8 pp. 2111 - 2113
DOI: 10.1021/ol500614q
論文10
Radical biaryl coupling of iodoarenes and benzene can be effectively promoted by tetrabutylammonium cyanoborohydride with air under photoirradiation conditions using a Xe lamp. The utility of this methodology is highlighted by its functional group tolerance and chemoselectivity

Chem. Commun.
A bromine-radical mediated three-component reaction comprising allenes, electron-deficient alkenes and allyl bromides: facile synthesis of 2-bromo-1,7-dienes
Kippo, T., Ryu, I.
Chem. Commun., 2014, 50, pp. 5993 - 5996
DOI: 10.1039/C4CC01597E
論文8
A bromine-radical mediated three-component coupling reaction was effectively achieved by the use of allenes, electron-deficient alkenes, and allyl bromides and led to the synthesis of 2-bromo-1,7-dienes in good to high yields. This protocol was extended to the three-component process using alkylidenecyclopropane, which gave 2-bromo-1,8-diene along with alkylidenecyclopentane.

Org. Lett
Synthesis of Fluorenones through Rhodium-Catalyzed Intramolecular Acylation of Biarylcarboxylic Acids
Fukuyama, T., Maetani, S., Miyagawa, K., Ryu, I.
Org. Lett., 2014, 16, 12 pp. 3216 - 3219
DOI: 10.1021/ol5012407
論文4
An efficient approach to the synthesis of fluorenones via the rhodium-catalyzed intramolecular acylation of biarylcarboxylic acids was developed. Using this procedure, fluorenones with various substituents can be synthesized in good to high yields. This work marks the first recorded use of catalytic intramolecular acylation to synthesize fluorenones.

J. Org. Chem
Borohydride-Mediated Radical Addition Reactions of Organic Iodides to Electron-Deficient Alkenes
Kawamoto, T., Uehara, S., Hirao, H., Fukuyama, T., Matsubara, H., Ryu, I.
J. Org. Chem., 2014, 79, 9 pp. 3999 - 4007
DOI: 10.1021/jo500464q
論文3
Cyanoborohydrides are efficient reagents in the reductive addition reactions of alkyl iodides and electron-deficient olefins. In contrast to using tin reagents, the reaction took place chemoselectively at the carbon–iodine bond but not at the carbon–bromine or carbon–chlorine bond. The reaction system was successfully applied to three-component reactions, including radical carbonylation. The rate constant for the hydrogen abstraction of a primary alkyl radical from tetrabutylammonium cyanoborohydride was estimated to be <1 × 104 M–1 s–1at 25 °C by a kinetic competition method. This value is 3 orders of magnitude smaller than that of tributyltin hydride.

Chem Sci
Sunlight photocatalyzed regioselective β-alkylation and acylation of cyclopentanones
Okada, M., Fukuyama, T., Yamada, K., Ryu, I., Ravelli, D, Fagnoni, M.
Chem. Sci., 2014, 5, 7 pp. 2893 - 2898
DOI: 10.1039/C4SC01072H
Sunlight photocatalyzed regioselective β-alkylation and acylation of cyclopentanones Sunlight-induced direct regioselective β-alkylation of cyclopentanones with electron-deficient alkenes was accomplished by using tetrabutylammonium decatungstate (TBADT) as the catalyst. The regiochemistry can be rationalized by a polar transition state for an SH2 reaction. In the presence of CO, the reaction gave the three-component β-acylation product in good yield.

BJOC
One-pot synthesis of cyanohydrin derivatives from alkyl bromides via incorporation of two one-carbon components by consecutive radical/ionic reactions
Sumino, S., Fusano, A., Okai, H., Fukuyama, T., Ryu, I.
Beilstein J. Org. Chem., 2014, 10, pp. 150 - 154
DOI: doi:10.3762/bjoc.10.12

The consecutive radical/ionic reaction consisting of radical formylation of alkyl bromides and nucleophilic addition of a cyanide ion was investigated, which gave moderate to good yields of cyanohydrin derivatives in one-pot.

 

 

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