Itaru Nakamura
Verified @tohoku.ac.jp
Graduate School of Science
Tohoku University
Scopus Publications
Scopus Publications
Itaru Nakamura., Keiryo Kubota, Hiroki Tashiro, Yushiro Saito, and Masahiro Terada
Wiley
AbstractN‐Sulfinylimines derived from ortho‐alkynylbenzaldehydes were efficiently converted into the corresponding 4‐sulfinylisoquinolines in good to excellent yields. The reaction proceeds via cyclization followed by intermolecular migration of the sulfinyl group from the nitrogen atom to the silver‐bound carbon of the resulting cyclized vinylsilver intermediate with the aid of either a counteranion or a nucleophilic species. Moreover, the Ag‐catalyzed reaction in the presence of quinidine acetate as a chiral nucleophilic cocatalyst yielded chiral isoquinolines with high enantioselectivities through a dynamic kinetic asymmetric transformation (DYKAT).
Itaru Nakamura, Riku Konta, Yasuhiro Ishida, Mai Tachibana, and Masahiro Terada
Wiley
AbstractA divergent synthesis of ortho‐anisidines was achieved by controlling Cu‐catalyzed [1,3]‐methoxy rearrangement. The reactions of N‐alkoxyanilines having an electron‐donating group (EDG), such as an alkyl or anisyl group, at the ortho position and a pivaloyl group on the nitrogen atom in the presence of catalytic amounts of IPrMeCuCl and AgNTf2 afforded the corresponding 6‐substituted 2‐anisidines with good product selectivity through a [1,3]‐rearrangement of the methoxy group to the unsubstituted ortho position. In contrast, the reactions of N‐ methoxyanilines having a benzyloxycarbonyl group on the nitrogen atom using IPrCuBr and AgBF4 as catalysts afforded 3‐substituted 2‐anisidines via a domino process involving a [1,3]‐rearrangement of the methoxy group to the EDG‐substituted ortho position followed by a [1,2]‐rearrangement of the EDG of the resulting ortho‐quinol imine intermediate.
Itaru Nakamura, Ichiro Muranushi, Takato Asoh, and Masahiro Terada
Wiley
AbstractSilver‐catalyzed reactions of N‐sulfenylanilides afforded the corresponding p‐sulfenylanilides in good to high yields with good para selectivity. The transformation has a high compatibility of functional groups, such as ester, bromo, and iodo groups. Mechanistic studies indicate that the rearrangement reaction proceeds through intermolecular transfer of the sulfenyl group.
Sheng Zhang, Hidenori Matsuyama, Itaru Nakamura, Masahiro Terada, and Tienan Jin
American Chemical Society (ACS)
A tandem oxidative ring expansion of a six- to seven-membered ring was developed to construct a new class of negatively curved polycyclic arenes embedded with oxepine and thiepine, namely, dibenzo[b,f]phenanthro[9,10-d]oxepine (DBPO) and dibenzo[b,f]phenanthro[9,10-d]thiepine (DBPT), respectively. Mechanistic studies disclosed that an unexpected [4 + 2] cycloadduct formed between the alkene moiety of o-biphenyl-linked methylenexanthenes and o-chloranil serves as a radical cation or a dication equivalent that facilitates the FeCl3-mediated tandem ring expansion process.
Itaru Nakamura, Mai Tachibana, Riku Konta, Hiroki Tashiro, and Masahiro Terada
MDPI AG
Cu-catalyzed reactions of N-alkoxy-2-methylanilines and alcohols in the presence of catalytic amounts of IPrCuBr and AgSbF6 afforded the corresponding meta-aminophenol derivatives in good to high yields. These reactions proceed via a [1,3]-rearrangement, in which the alkoxy group migrates from the nitrogen atom to the methyl-substituted ortho position, followed by an oxa-Michael reaction of the resulting ortho-quinol imine intermediate.
Mao Suzuki, Masahiro Terada, and Itaru Nakamura
Royal Society of Chemistry (RSC)
[1,3]-Nitrogen rearrangement reactions of O-aryl ketoximes was catalytically promoted by IPrCuBr and BF3·OEt2. The oxidative addition of the N–O bond to the Cu catalyst is accelerated by donation of electrons from both nitrogen and oxygen atoms.
Itaru Nakamura
The Society of Synthetic Organic Chemistry, Japan
Takato Asoh, Hiroki Tashiro, Masahiro Terada, and Itaru Nakamura
American Chemical Society (ACS)
Itaru Nakamura, Satoru Nozawa, Yasuhiro Ishida, Ichiro Muranushi, Alexandra Mayerweg, and Masahiro Terada
Royal Society of Chemistry (RSC)
Copper-catalyzed [1,3]-alkoxy rearrangement reactions of polycyclic arenes and heteroarenes, such as naphthalenes, phenanthrenes, and indoles, afforded the corresponding ortho-aminoarenol derivatives in good yields and in a site-selective manner.
Itaru Nakamura, Kazuki Masukawa, Yasuhiro Ishida, and Masahiro Terada
American Chemical Society (ACS)
A Cu-catalyzed cascade reaction between N-alkoxyanilines having an electron-donating functional group at the ortho position and dienophiles, such as N-methylmaleimide, styrene, and indene, proceeded via a dearomative [1,3]-alkoxy rearrangement followed by the Diels-Alder reaction, affording the corresponding ketimines with highly functionalized bicyclic skeletons in an efficient and stereoselective manner. Our mechanistic investigations indicated that the [1,3]-rearrangement is the rate-determining process, efficiently suppressing unfavorable side reactions.
Hiroki Tashiro, Masahiro Terada, and Itaru Nakamura
Wiley
Au-Catalyzed reactions of alkynyl N -sulfinylimines were utilized to produce the corresponding 2 H -azirines that possess sulfenyl and acyl groups at the 3 position of the azirine ring, in good to excellent yields. These reactions involved an internal oxygen transfer of the sulfinyl oxygen to form a thiooxime intermediate tethered to an a-oxo gold carbene moiety. The subsequent N-S bond insertion into the carbene resulted in a ring contraction.
Itaru Nakamura, Arinobu Hirayama, Shinya Gima, and Masahiro Terada
Wiley
The Au-catalyzed reactions of O- homopropaylic oximes afforded the 3-alkenylated isoxazolines in good to high yields. The mechanistic studies suggest that the reaction proceeds via exo- cyclization followed by intermolecular methylene group transfer. In addition, oligomeric species of the starting material were observed in the reaction mixture by mass spectra, supporting our proposed mechanism, which proceeds through repeated intermolecular C-C bond forming process.
Itaru Nakamura, Keigo Shiga, Mao Suzuki, and Masahiro Terada
Georg Thieme Verlag KG
A synthetic protocol to access O-tert-propargylic oximes derived from tertiary propargylic alcohols was established via Nicholas reaction. Thus, BF3·OEt2-mediated reaction between the dicobalt hexacarbonyl complex of tert-propargylic alcohols and p-nitrobenzaldoxime followed by decomplexation with cerium(IV) ammonium nitrate afforded the corresponding O-tert-propargylic oximes in good to high yields. The obtained O-tert-propargylic oximes were effectively converted into heterocycles, such as four-membered cyclic nitrones, oxazepines, and isoxazolines, by using π-Lewis acidic catalysts.
Itaru Nakamura, Hiroki Tashiro, Yasuhiro Ishida, and Masahiro Terada
American Chemical Society (ACS)
meta-Substituted anilines were efficiently synthesized via copper-catalyzed [1,3]-methoxy rearrangement of N-methoxyanilines followed by Michael addition of nucleophiles to the in situ generated ortho-quinol imine. The present reaction exhibits excellent applicability of para-substituents, such as vinyl, methylthio, ester, and bromo, and carbon nucleophiles, such as 1,3,5-trimethoxybenzene, N-methylindole, and dimethyl malonate. Thus, the present rearrangement can resolve problems stemming from oxidation reactions, such as the use of stoichiometric amounts of oxidants and low compatibility of electron-withdrawing groups.
Itaru Nakamura and Masahiro Terada
Elsevier BV
Itaru Nakamura and Masahiro Terada
The Society of Synthetic Organic Chemistry, Japan
Keigo Shiga, Ilya D. Gridnev, Masahiro Terada, and Itaru Nakamura
Royal Society of Chemistry (RSC)
Au-catalyzed skeletal rearrangement reaction of O-propargylic oxime proceeded via N–O bond cleavage with the aid of a Brønsted base cocatalyst.
Shinya Gima, Keigo Shiga, Masahiro Terada, and Itaru Nakamura
Georg Thieme Verlag KG
We successfully extended our gold-catalyzed skeletal rearrangement reaction of O-propargylic oximes through C=N bond cleavage to include substrates having an ester group on the oxime moiety, affording the corresponding 2-isoxazolines having an alkoxycarbonylmethylene group at the 4-position in good to high yields. Our mechanistic studies indicated that the transfer of the alkoxycarbonylmethylene group proceeded in an intermolecular manner, confirming that the reaction proceeds through cyclization followed by intermolecular transfer of the alkoxycarbonylmethylene group.
Itaru Nakamura, Mao Owada, Takeru Jo, and Masahiro Terada
Beilstein Institut
A cationic cobalt catalyst efficiently promoted the reaction of N-alkoxycarbonyloxyanilines at 30 °C, affording the corresponding ortho-aminophenols in good to high yields. As reported previously, our mechanistic studies including oxygen-18 labelling experiments indicate that the rearrangement of the alkoxycarbonyloxy group proceeds in [1,3]-manner. In this article, we discuss the overall picture of the cobalt-catalysed [1,3]-rearrangement reaction including details of the reaction conditions and substrate scope.
Yasuhiro Ishida, Itaru Nakamura, and Masahiro Terada
American Chemical Society (ACS)
Multisubstituted ortho-anisidines were efficiently synthesized via cationic N-heterocyclic carbene-Cu-catalyzed domino rearrangement of N-methoxyanilines that possess an electron-donating functional group, such as an alkyl or an aryl group, at the ortho position. The reaction proceeded first through a [1,3]-rearrangement of the methoxy group to the ortho position bound to the electron-donating substituent, followed by a semipinacol type [1,2]-rearrangement of the electron-donating group from the ortho to the meta position. Mechanistic studies suggest that both rearrangement reactions are promoted by a cationic Cu catalyst.
Shinya Gima, Itaru Nakamura, and Masahiro Terada
Wiley
Enantio-enriched isoxazoles having a chiral side chain at the 4 position were efficiently synthesized by chirality transfer in the gold-catalyzed cyclization/intermolecular methylene transfer sequence followed by carbonyl ene reaction. The chiral information of enantio-enriched O-propargylic oximes was completely retained during gold-catalyzed reaction. The subsequent carbonyl ene reaction between the resulting 4-methylenated isoxazoline and glyoxylates proceeded with excellent level of chirality transfer by using BF3·OEt2 as Lewis acid. According to the relationship of absolute configuration between the starting propargylic oxime and the obtained alcohol having an isoxazole, the carbonyl ene-reaction proceeds in an endo manner.
Itaru Nakamura, Takeru Jo, Yasuhiro Ishida, Hiroki Tashiro, and Masahiro Terada
American Chemical Society (ACS)
The [1,3]-alkoxy rearrangement reactions of N-alkoxyanilines were efficiently catalyzed by cationic N-heterocyclic carbene (NHC)-Cu catalysts in affording 2-alkoxyaniline derivatives in good to excellent yields with high functional group compatibility. For N-alkoxyanilines having an electron-withdrawing substituent at the meta-position, the alkoxy group selectively migrated to the more hindered ortho-position. In contrast, the alkoxy group migrated to the less hindered ortho-position for N-alkoxyanilines having an electron-donating substituent. Mechanistic studies suggest that the rearrangement reactions proceed via an intramolecular route.
Itaru Nakamura, Keisuke Takeda, Yoshinori Sato, and Masahiro Terada
Wiley
We show that N-alkynylnitrones are efficiently converted to nitrogenous heterobicyclic compounds with a nitrogen atom at the bridgehead position by using a RhIII -catalyst. Our mechanistic studies suggest that the reaction proceeds via an allene intermediate, which is generated in situ through RhIII -catalyzed isomerization of the alkyne group.
Itaru Nakamura, Yoshiharu Oyama, Dong Zhang, and Masahiro Terada
Royal Society of Chemistry (RSC)
O-Homoallenylic α,β-unsaturated oximes were efficiently converted to the corresponding 2-alkenylpyridine derivatives by microwave irradiation.
Itaru Nakamura, Mao Owada, Takeru Jo, and Masahiro Terada
American Chemical Society (ACS)
O-(Alkoxycarbonyl)-N-arylhydroxylamines were efficiently converted to 2-aminophenol derivatives by cationic cobalt catalysts at 30 °C. The results of 18O-labeling experiments suggested that rearrangement of the alkoxycarbonyl group from the aniline nitrogen to the ortho position proceeded in an unprecedented [1,3] manner.