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発表論文

Published in 2005

200509
Tin-Free Radical Carbonylation: Thiol Ester Synthesis Using Alkyl Allyl Sulfone Precursors, Phenyl Benzenethiosulfonate, and CO
Kim, S., Kim, S., Otsuka, N., Ryu, I.
Angew. Chem. Int. Ed., 2005, 44, 38 pp. 6183 - 6186
DOI: 10.1002/anie.200501606

Remove contents from tin … Thiol esters have been successfully synthesized through tin-free radical carbonylation (see scheme; V-40=initiator). This approach can be further extended to sequential radical reactions involving cyclization, carbonylation, and trapping of acyl radicals by phenyl benzenethiosulfonate.

Unknown
Synthesis of Functionalized Hydroquinones via [Cp*RuCl2]2-Catalyzed Cocyclization of Alkynes, α,β-Unsaturated Carbonyl Compounds, and Carbon Monoxide
Fukuyama, T., Yamaura, R., Higashibeppu, Y., Okamura, T., Ryu, I., Kondo, T., Mitsudo, T.
Org. Lett., 2005, 7, 26 pp. 5781 - 5783
DOI: 10.1021/ol052291s

Catalytic [2 + 2 + 1 + 1] cocyclization reaction of an alkyne, an alkene, and two molecules of carbon monoxide, leading to functionalized hydroquinones, was studied. Using [Cp*RuCl2]2 as a catalyst, we found that a variety of electron-deficient alkenes, such as α,β-unsaturated ketones, esters, amides, and nitriles, can be employed as an alkene coupling partner to give the corresponding hydroquinones.

journal_ec
Radical Cyanocarbonylation Using Alkyl Allyl Sulfone Precursors
Kim, S., Cho, C. H., Kim, S., Uenoyama, Y., Ryu, I.
Synlett., 2005, 20, pp. 3160 - 3162
DOI: 10.1055/s-2005-921932

Acyl cyanides have been prepared by the three-component coupling reactions comprised of alkyl allyl sulfones, carbon monoxide, and p-tolylsulfonyl cyanide under tin-free radical reaction conditions.

journal_ec
Quadraphasic phase-vanishing method: Application to bromination reactions that produce acidic by-products
Rahman, M. T., Kamata, N., Matsubara, H., Ryu, I.
Synlett., 2005, 17, pp. 2664 - 2666
DOI: 10.1055/s-2005-917103

A quadraphasic phase-vanishing method was developed that employs water as the fourth phase acting as an ‘acid scavanger phase'. This protocol worked well for bromination of aceto­phenones giving high yields of the corresponding α-bromo ketones.

Unknown
CO-trapping reaction under thermolysis of alkoxyamines: Application to the synthesis of 3,4-cyclopenta-1-tetralones
Uenoyama, Y., Tsukida, M., Doi, T., Ryu, I., Studer, A.
Org. Lett., 2005, 7, 14 pp. 2985 - 2988
DOI: 10.1021/ol050951n

An efficient one-pot sequence comprising a PRE-mediated radical 5-exo-cyclization, a radical carbonylation, a nitroxide trapping reaction, and a subsequent acid-catalyzed Friedel−Craft-type acylation provides a new entry into 3,4-cyclopenta-1-tetralones. Eight examples are presented.

Unknown
An anionic strategy for three- and four-component coupling reactions leading to ketone frameworks based on vinylogous conversion of dilithio ketone α,β-dianions
Yamato, S., Yamamura, G,, Komatsu, M., Arai, M., Fukuyama, T., Ryu, I.
Org. Lett., 2005, 7, 12 pp. 2489 - 2491
DOI: 10.1021/ol050813y

Ketone α,δ-dianions are generated by vinylogous extension of ketone α,β-dianions with alkenes such as vinylarenes, vinylsilanes, and vinyl sulfides, which then undergo reactions at the δ and α positions with different electrophiles, creating ketone frameworks. This work represents a cascade-type anion method that achieved three- and four-carbon component assembly reactions leading to ketones.

200503
Theoretical Study on the Isomerization Behavior between α,β-Unsaturated Acyl Radicals and α-Ketenyl Radicals
Matsubara, H., Ryu, I., Schiesser, H.
J. Org. Chem., 2005, 70, 9 pp. 3610 - 3617
DOI: 10.1021/jo047868i

Ab initio calculations using 6-311G**, cc-pVDZ, aug-cc-pVDZ, and a (valence) double-ζ pseudopotential (DZP) basis set, with (QCISD, CCSD(T)) and without (UHF) the inclusion of electron correlation, and density functional methods (BHandHLYP, B3LYP) predict that α,β-unsaturated acyl radicals and α-ketenyl radicals exist as isomers. At the CCSD(T)/cc-pVDZ//BHandHLY/cc-pVDZ level of theory, energy barriers of 15.1 and 17.7−21.7 kJ mol-1 are calculated for the isomerization of s-trans-propenoyl and s-trans-crotonoyl radical to ketenylmethyl and 1-ketenylethyl radical, respectively. Similar results are obtained for the reactions of s-trans isomers involving silyl, germyl, and stannyl groups with energy barriers (ΔE) of 12.2−12.4, 13.1−13.9, and 12.9−18.2 kJ mol-1 at the CCSD(T)/DZP//BHandHLYP/DZP calculation, respectively. These results suggest that α,β-unsaturated acyl radicals and α-ketenyl radicals are not canonical forms but are isomeric species that can rapidly interconvert.

200502
Acetylene Carbonylation by Radicals: Tin Radical Catalyzed Synthesis of α-Methylene Amides from 1-Alkynes, Carbon Monoxide, and Amines
Uenoyama, Y., Fukuyama, T., Nobuta, O., Matsubara, H., Ryu, I.
Angew. Chem. Int. Ed., 2005, 44, 7 pp. 1075 - 1078
DOI: 10.1002/anie.200461954

A convergent synthesis of α-methylene amides exploits a hybrid radical/ionic concept in which radical carbonylation of alkynes is followed by ionic trapping of the resulting carbonyl-containing radical species with amines (see scheme). The reaction of substituted terminal alkynes with pressurized CO, Bu3SnH, and 2,2′-azobisisobutyronitrile in the presence of a large excess of amines gave good yields of the corresponding α-methylene amides.

Tetrahedron
Generation of ketone dilithio α,β-dianions and their reactions with electrophiles
Nakahira, H., Ikebe, M., Oku, Y., Sonoda, N., Fukuyama, T., Ryu, I.
Tetrahedron., 2005, 61, 13 pp. 3383 - 3392
DOI: 10.1016/j.tet.2005.01.047

Ketone dilithio α,β- and α,β′-dianions can be generated by a tin–lithium exchange reaction of the lithium enolate of β-tributyltin substituted ketones. A chelation-aided approach, which employs β-dichlorobutyltin substituted ketones and n-BuLi, is also useful for the generation of ketone α,β-dianions having the Z-geometry at the alkene. The generated dianions can be transformed into substituted ketones by reaction with various carbon electrophiles.

 

 

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