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| 1.
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Suga, Takuya ; Shimizu, Shoma ; Ukaji, Yutaka ; 菅, 拓也 ; 宇梶, 裕
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金沢大学理工研究域物質化学系<br />A concise method to directly generate benzyl radicals from benzyl alcohol derivatives has been devel
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oped. The simple and inexpensive combination of TiCl4(collidine) (collidine = 2,4,6-collidine) and manganese powder afforded a low-valent titanium reagent, which facilitated homolytic cleavage of benzylic C–OH bonds. The application to radical conjugate addition reactions demonstrated the broad scope of this method. The reaction of various benzyl alcohol derivatives with electron-deficient alkenes furnished the corresponding radical adducts.<br />Embargo Period 12 months
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Suga, Takuya ; Ukaji, Yutaka ; 菅, 拓也 ; 宇梶, 裕
概要:
金沢大学理工研究域物質化学系<br />A nickel-catalyzed cross-electrophile coupling reaction between benzyl alcohols and aryl halides has
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been developed using a homolytic C–O bond cleavage protocol that has recently been established. The treatment of a benzyl alcohol and aryl halide with a nickel catalyst and low-valent titanium reagent generated from TiCl4(lutidine) (lutidine = 2,6-lutidine) and manganese powder afforded the cross-coupled product in high yield. A mechanistic study indicated the intermediacy of the benzyl radicals that originate from the benzyl alcohols.<br />Embargo Period 12 months<br />This work was supported in part by a Mitsui Chemicals Award in Synthetic Organic Chemistry, Japan, a UBE Industries Foundation Award, and the Kanazawa University SAKIGAKE project.
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3. One‐Shot Radical Cross Coupling Between Benzyl Alcohols and Alkenyl Halides Using Ni/Ti/Mn System
Suga, Takuya ; Takahashi , Yuuki ; Ukaji, Yutaka ; 宇梶, 裕
概要:
金沢大学理工学域物質科学系<br />A “one‐shot” cross coupling between benzyl alcohols and alkenyl halides has been established. A combi
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nation of low‐valent Ti‐mediated C−OH homolysis and the prominent chemistry of Ni‐based radical catalysis afforded the desired cross‐coupled product with good efficiency. The reaction proceeded regardless of the electronic property of benzyl alcohols, and Ar−B bond remained intact throughout the reaction. Alkenyl bromides with various substitution patterns were applicable to this reaction. Attempts for utilizing sterically demanding tri‐substituted alkenes indicated that the steric hinderance mainly inhibited the radical‐trapping by Ni species. This reaction can be a simple and efficient strategy for synthesizing densely substituted allylbenzene derivatives.
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Takahashi, Ryosuke ; Nga, Hang Thi Phan ; Suga, Takuya ; Soeta, Takahiro ; Ukaji, Yutaka ; 菅, 拓也 ; 宇梶, 裕
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金沢大学理工学研究域物質化学系<br />Optically active γ-lactams were prepared by asymmetric dicarbonylation reaction of N-arylsulfonyl h
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omoallylic amines catalyzed by palladium in the presence of copper(I) triflate. By the use of benzyl-substituted bioxazoline ligand, the corresponding γ-lactams were obtained with enantioselectivities of up to 67% ee.<br />許可を得て公開2019.11.11.
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猪股, 勝彦 ; 宇梶, 裕 ; Inomata, Katsuhiko ; Ukaji, Yutaka
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金沢大学大学院自然科学研究科物質創成<br />金沢大学理学部
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Sakai, Hiroki ; Ding, Xia ; Yoshida, Tetsusuke ; Fujinami, Shuhei ; Ukaji, Yutaka ; Inomata, Katsuhiko
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金沢大学金沢大学理工研究域物質化学系<br />The regio- and enantioselective hetero Diels-Alder reaction of a nitroso compound with a cyclic
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dienol, cyclohexa-1,3-dienylmethanol, has been realized utilizing stoichiometric amount of tartaric acid ester as a chiral auxiliary to afford the corresponding dihydro-1,2-oxazine with complete regioselectivity and high enantioselectivity of up to 92% ee. A catalytic version of the asymmetric hetero Diels-Alder reaction of nitroso compounds with the dienol was also achieved to afford the corresponding optically active cycloadducts with up to 83% ee. The addition of MS 4A was crucial to realize reproducible high enantioselectivity. © 2008 The Japan Institute of Heterocyclic Chemistry All rights reserved.
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| 7.
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Wei, Weilin ; Hamamoto, Yoshihira ; Ukaji, Yutaka ; Inomata, Katsuhiko
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金沢大学大学院自然科学研究科物質創成<br />Asymmetric addition of diphenylzinc to C-alkynyl nitrones was achieved by utilizing di(t-butyl)
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(R,R)-tartrate as a chiral auxiliary to afford the corresponding optically active (S)-N-(1-phenyl-3-substituted prop-2-ynyl)hydroxylamines. By the addition of a product-like additive, enantiomeric enhancement was observed. A mixed zinc reagent, PhZnMe, improved the enantioselection to afford hydroxylamines in up to 92% ee. © 2008 Elsevier Ltd. All rights reserved.
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| 8.
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Serizawa, Masakazu ; Fujinami, Shuhei ; Ukaji, Yutaka ; Inomata, Katsuhiko
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金沢大学理工研究域物質化学系<br />The asymmetric addition of alkynylzinc reagents, prepared in situ from dimethylzinc and 1-alkynes, t
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o α-dinitrones derived from glyoxal and N-(4-isopropylbenzyl)hydroxylamine was investigated by utilizing dicyclohexyl (R,R)-tartrate as a chiral auxiliary. The addition reaction of methyl(2-phenylethynyl)zinc afforded the corresponding optically active C2-symmetric (R,R)-bis(hydroxylamine) derivative with enantioselectivities of 90% and 81% ee by utilizing a stoichiometric and catalytic amount of the tartrate, respectively. Furthermore, the catalytic addition reaction of several alkynylzinc reagents also furnished the corresponding bis(hydroxylamine) with moderate to good enantioselectivities. © 2008 Elsevier Ltd. All rights reserved.
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| 9.
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Yoshida, Mari ; Sassa, Naotaro ; Kato, Tomomitsu ; Fujinami, Shuhei ; Soeta, Takahiro ; Inomata, Katsuhiko ; Ukaji, Yutaka
概要:
Desymmetrization of the divinyl carbinol 1,4-pentadien-3-ol was accomplished by the asymmetric 1,3-dipolar cycloaddition
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of azomethine imines based on a magnesium-mediated, multinucleating chiral reaction system utilizing diisopropyl (R,R)-tartrate as the chiral auxiliary. The corresponding optically active trans-pyrazolidines, each with three contiguous stereogenic centers, were obtained with excellent regio-, diastereo-, and enantioselectivity, with results as high as 99%ee. This reaction was shown to be applicable to both aryl- and alkyl-substituted azomethine imines. The use of a catalytic amount of diisopropyl (R,R)-tartrate was also effective when accompanied by the addition of MgBr2. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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| 10.
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Takahashi, Kana ; Iwamoto, Ryoji ; Sakata, Ryo ; Soeta, Takahiro ; Inomata, Katsuhiko ; Ukaji, Yutaka
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Oxidation of 4-methylpyrrole-2-carboxylates with DDQ in the presence of a glycol proceeded smoothly on the methyl group
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at the C4 position regioselectively to afford the corresponding pyrrole-2,4-dicarboxylates directly. Direct oxidation of a methyl group of 2,4,6-trimethylphenol and 3-methyl-9H-carbazole into carboxylates was also demonstrated. © 2012 The Japan Institute of Heterocyclic Chemistry.
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