The Ryu Research Group, Department of Chemistry, Graduate School of Science, Osaka Prefecture University

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Published in 2013

J Flow Chem cover
Continuous Microflow Bromination of Alkenes Combined with a Circulatory Recycling of a Fluorous Polyether as a Bromine Support
T. Fukuyama, Md. T. Rahman, N. Kamata, M. Tokizane, Y. Fukuda, I. Ryu
J. Flow Chem., 2013, 3, pp. 4 - 6
DOI: 10.1556/JFC-D-12-00023
Fluorous multi-phase bromination reaction of alkenes could be successfully transformed to a continuous microflow system in which a fluorous polyether, Galden® HT135, is employed as a recyclable molecular bromine support. This microflow bromination of alkenes could be carried out without any temperature control or an inert gas atmosphere. The circulatory continuous microflow reaction system for bromination of cyclohexene was created which gave 8.3 g (85%) of dibromocyclohexane after continuous operation for 6 h.

Ruthenium-Catalyzed Addition of 1,3-Diketones to Terminal Alkynes
Léotard, B., Fukuyama, T., Higashibeppu, Y., Brancour, C., Okamoto, H., Ryu, I.
Synlett, 2013, 24, 17 pp. 2287 - 2291
DOI: 10.1055/s-0033-1339708
i_u0619_ga_10-1055_s-0033-1339708 Ruthenium complex [RuCl2(CO)3]2 catalyzes the addition of 1,3-diketones to terminal alkynes. We observed C-addition with acyclic 1,3-diketones, whereas the use of cyclic 1,3-diketones systematically led to O-addition reactions.

Synthesis of Alkylated Nitriles by [RuHCl(CO)(PPh3)3]-catalyzed Alkylation of Acetonitrile Using Primary Alcohols
Kuwahara, T., Fukuyama, T., Ryu, I.
Chem. Lett., 2013, 42, 10 pp. 1163 - 1165
DOI: 10.1246/cl.130465

Alkylation reaction of acetonitrile using primary alcohols is effectively catalyzed by [RuHCl(CO)(PPh3)3] in the presence of K3PO4 as a base. Both benzylic and non-benzylic alcohols coupled with acetonitrile to give alkylated nitriles in good yields

Flow Giese reaction using cyanoborohydride as a radical mediator
Fukuyama, T., Kawamoto, T., Kobayashi, M., Ryu, I.
Beilstein J. Org. Chem., 2013, 9, pp. 1791 - 1796
DOI: 10.3762/bjoc.9.208

Tin-free Giese reactions, employing primary, secondary, and tertiary alkyl iodides as radical precursors, ethyl acrylate as a radical trap, and sodium cyanoborohydride as a radical mediator, were examined in a continuous flow system. With the use of an automated flow microreactor, flow reaction conditions for the Giese reaction were quickly optimized, and it was found that a reaction temperature of 70 °C in combination with a residence time of 10–15 minutes gave good yields of the desired addition products. continuous flow system cyanoborohydride flow chemistry iodoalkanes microreactor tin-free Giese reaction Introduction Organo halides are among the most useful precursors to access

RSC Advances
Ruthenium hydride/nitrogen tridentate ligand-catalyzed α-alkylation of acetamides with primary alcohols
Kuwahara, T., Fukuyama, T., Ryu, I.
RSC Adv., 2013, 3, pp. 13702 - 13704
DOI: 10.1039/C3RA42834F

The α-alkylation reaction of acetamides with primary alcohols to afford the corresponding amides was accomplished effectively using RuHCl(CO)(PPh3)3 as a catalyst, nitrogen tridentate ligand L1 as an additive, and KOtBu as a base. While the addition of bpy was effective only for benzylic alcohols, L1 affected the alkylation reaction when both benzylic and non-benzylic type alcohols were used.

A construction of 4,4-spirocyclic γ-lactams by tandem radical cyclization with carbon monoxide
Ueda, M., Uenoyama, Y., Terasoma, N., Doi, S., Kobayashi, S., Ryu, I., Murphy, J. A.
Beilstein J. Org. Chem., 2013, 9, pp. 1340 - 1345
DOI: 10.3762/bjoc.9.151

A straightforward synthesis of 4,4-spirocyclic indol γ-lactams by tandem radical cyclization of iodoaryl allyl azides with CO was achieved. The reaction of iodoaryl allyl azides, TTMSS and AIBN under CO pressure (80 atm) in THF at 80 °C gave the desired 4,4-spirocyclic indoline, benzofuran, and oxindole γ-lactams in moderate to good yields.

Transition-Metal-Free Suzuki-Miyaura Coupling Reaction of Arylpropar­gylic Bromides with Aryl- and Alkenylboronic Acids
Ueda, M., Nishimura, K., Ryu, I.
synlett, 2013, 24, 13 pp. 1683 - 1686
DOI: 10.1055/s-0033-1339199

In the absence of transition-metal catalyst, Suzuki-Miyaura coupling reaction between aryl- and alkenylboronic acids and arylpropargylic bromides proceeded to give the corresponding acetylenic products selectively.

Synthesis of Alkyl Aryl Ketones by Pd/Light Induced Carbonylative Cross-Coupling of Alkyl Iodides and Arylboronic Acids
Sumino, S., Ui, T., Ryu, I.
Org. Lett., 2013, 15, 12 pp. 3142 - 3145
DOI: 10.1021/ol401363t

Alkyl aryl ketones were synthesized by the carbonylative cross-coupling reaction of alkyl iodides and arylboronic acids under combined Pd/light conditions. In this reaction, it is likely that an acylpalladium species would be formed via carbonylation of the alkyl radical, which would then undergo transmetalation of an arylboronic acid to give the corresponding acyl(aryl)palladium species, ready to undergo reductive elimination to yield the alkyl aryl ketone.

Reductive Bromine Atom-Transfer Reaction
Sumino, S., Fusano, A., Ryu, I.
Org. Lett., 2013, 15, 11 pp. 2826 - 2829
DOI: 10.1021/ol4011536

Atom-transfer radical (ATR) reactions of alkenes with R–X usually give products having new C–C and C–X bonds at the adjacent carbons. However, when the reaction was carried out under irradiation using a low-pressure Hg lamp, addition/reduction products were obtained in good yield. Hydrogen bromide, formed by H-abstraction of a bromine radical from alkenes, is likely to play a key role in the reductive ATR reaction.

Modernized Low Pressure Carbonylation Methods in Batch and Flow Employing Common Acids as a CO Source
Brancour, C., Fukuyama, T., Mukai, Y., Skrydstrup, T., Ryu, I.
Org. Lett., 2013, 15, 11 pp. 2794 - 2797
DOI: 10.1021/ol401092a

Carbonylation reactions, such as Heck, Sonogashira, and radical carbonylations, were successfully carried out in a “two-chamber reactor” where carbon monoxide was producedex situ by the Morgan reaction (dehydration of formic acid by sulfuric acid). By a subsequent application in a microflow system using a “tube-in-tube” reactor where gas-permeable Teflon AF2400 was used as the inner tube, it is demonstrated that formic acid/sulfuric acid can be employed concomitantly with an amine base such as triethylamine in the Heck aminocarbonylation of aryl iodide.

Rhodium-Catalyzed Decarbonylative C–H Arylation of 2-Aryloxybenzoic Acids Leading to Dibenzofuran Derivatives
Maetani, S., Fukuyama, T., Ryu, I.
Org. Lett., 2013, 15, 11 pp. 2754 - 2757
DOI: 10.1021/ol4010905

Rhodium-catalyzed intramolecular C–H arylation of 2-aryloxybenzoic acids proceeded accompanied by decarbonylation to give dibenzofuran derivatives in high yields. The present reaction is widely applicable to substrates bearing various functionalities.

Efficient C–H/C–N and C–H/C–CO–N Conversion via Decatungstate-Photoinduced Alkylation of Diisopropyl Azodicarboxylate
Ryu, I., Tani, A., Fukuyama, T., Ravelli, D., Montanaro, S., Fagnoni, M.
Org. Lett., 2013, 15, 10 pp. 2554 - 2557
DOI: 10.1021/ol401061v

Tetrabutylammonium decatungstate (TBADT) accelerated the addition of C–H bonds to the N═N double bond of diisopropyl azodicarboxylate (DIAD) under irradiation conditions. The photoinduced three-component coupling between cyclic alkanes, CO, and DIAD was also achieved to give the corresponding acyl hydrazides.

Efficient Hydroxymethylation Reactions of Iodoarenes Using CO and 1,3-Dimethylimidazol-2-ylidene Borane
Kawamoto, T., Okada, T., Curran, D. P., Ryu, I.
Org. Lett., 2013, 15, 9 pp. 2144 - 2147
DOI: 10.1021/ol4006294

A hydroxymethylation reaction of a variety of iodoarenes proceeded effectively in the presence of CO, NHC-borane, diMeImd-BH3 (2) as a radical mediator, and a catalytic amount of AIBN. The reaction took place chemoselectively at the aryl-iodine bond but not at the aryl-bromine and aryl-chlorine bonds. A three-component coupling reaction comprising aryl iodides, CO, and electron-deficient alkenes also proceeded well to give unsymmetrical ketones in good yields. Control experiments show that 2 would act as a hydrogen donor to acyl radicals and iodinated NHC-borane as a reducing agent of aldehydes.

Free-Radical-Mediated [2 + 2 + 1] Cycloaddition of Acetylenes, Amidines, and CO Leading to Five-Membered α,β-Unsaturated Lactams
Fukuyama, T., Nakashima, N., Okada, T., Ryu, I.
J. Am. Chem. Soc., 2013, 135, 3 pp. 1006 - 1008
DOI: 10.1021/ja312654q

A free-radical-mediated [2 + 2 + 1] cycloaddition reaction comprising acetylenes, amidines, and CO was achieved by radical chain reaction to give five-membered α,β-unsaturated lactams in good yields. Both acyclic and cyclic amidines reacted with a variety of terminal acetylenes to afford monocyclic, bicyclic, and tricyclic lactams. We propose that vinyl radical carbonylation and nucleophilic addition of the amidine onto the resulting α-ketenyl radical give stable intermediates that are ready to undergo five-membered ring closure with elimination of tin radical.

Bromine Radical-Mediated Sequential Radical Rearrangement and Addition Reaction of Alkylidenecyclopropanes
Kippo, T., Hamaoka, K., Ryu, I.
J. Am. Chem. Soc, 2013, 135, 2 pp. 632 - 635
DOI: 10.1021/ja311821h

Bromine radical-mediated cyclopropylcarbinyl-homoallyl rearrangement of alkylidenecyclopropanes was effectively accomplished by C–C bond formation with allylic bromides, which led to the syntheses of 2-bromo-1,6-dienes. A three-component coupling reaction comprising alkylidenecyclopropanes, allylic bromides, and carbon monoxide also proceeded well to give 2-bromo-1,7-dien-5-ones in good yield.



Laboratory for Advanced Organic Synthesis
Organization for Research Promotion Osaka Prefecture University
Sakai, Osaka 599-8531, JAPAN
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