The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Kazuaki Ishihara - One of the best experts on this subject based on the ideXlab platform.
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Hypoiodite catalysed oxidative homocoupling of arenols and tandem oxidation cross coupling of hydroquinones with arenes
Chemical Communications, 2021Co-Authors: Muhammet Uyanik, Dai Nagata, Kazuaki IshiharaAbstract:We report the Hypoiodite-catalyzed oxidative C–C homocoupling of arenols to biarenols or biquinones using aqueous hydrogen peroxide as an oxidant. In addition, by combining Hypoiodite catalysis and lipophilic Lewis acid-assisted Bronsted acid catalysis under aqueous conditions, we achieved a tandem oxidation/cross-coupling reaction of hydroquinones with electron-rich arenes. These results highlight the substantial scope of Hypoiodite/acid co-catalysis for use in oxidative coupling reactions.
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Hypoiodite catalyzed chemoselective tandem oxidation of homotryptamines to peroxy and epoxytetrahydropyridoindolenines
Organic Letters, 2020Co-Authors: Muhammet Uyanik, Hiroki Tanaka, Kazuaki IshiharaAbstract:We developed the Hypoiodite-catalyzed tandem dearomative peroxycyclization of homotryptamine derivatives to peroxytetrahydropyridoindolenines under mild conditions. During the course of a mechanistic study, we found that a tandem oxidative cyclization/epoxidation as an unexpected reaction proceeded in the presence of TEMPO as an additive. Intramolecular oxidative aminocyclization of homotryptamines at the C-2 position would give tetrahydropyridoindole, a common intermediate for both reactions. Control experiments suggested that while oxidative coupling with TBHP at the C-3 position might afford peroxyindolenines, a preferential electrophilic addition of TEMPO+, which might be generated in situ by the Hypoiodite-catalyzed oxidation of TEMPO, at C-3 position followed by elimination and epoxidation might give epoxyindolenines. This serendipitous finding prompted us to develop a chemoselective divergent synthesis of peroxy- and epoxyindolenines by simple modification of the reaction conditions.
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Chemoselective oxidative generation of ortho-quinone methides and tandem transformations
Nature Chemistry, 2020Co-Authors: Muhammet Uyanik, Kohei Nishioka, Ryutaro Kondo, Kazuaki IshiharaAbstract:ortho -Quinone methides are useful transient synthetic intermediates in organic synthesis. These species are most often generated in situ by the acid- or base-mediated transformation of phenols that have been pre-functionalized at a benzylic position, or by biomimetic oxidation of the corresponding ortho -alkylphenols with metal oxidants or transition-metal complexes. Here we describe a method for the transition-metal-free oxidative generation of o -QMs from ortho -alkylarenols, using Hypoiodite catalysis under nearly neutral conditions, which can then be applied in one-pot tandem reactions. This method for the chemoselective oxidative generation of ortho -quinone methides may prove superior to previous methods with respect to environmental issues and scope, and can be applied to various tandem reactions such as inter- or intramolecular [4 + 2] cycloaddition, oxa-6π-electrocyclization, conjugate addition and spiroepoxidation. ortho -Quinone methides are highly reactive transient intermediates found in some organic syntheses and biological processes. The generation of these species often requires pre-functionalized substrates and/or metal oxidants, but now the chemoselective oxidative generation of ortho -quinone methides from ortho -alkylarenols has been achieved using Hypoiodite catalysis under nearly neutral conditions.
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high performance ammonium Hypoiodite oxone catalysis for enantioselective oxidative dearomatization of arenols
ACS Catalysis, 2019Co-Authors: Muhammet Uyanik, Takehiro Kato, Naoto Sahara, Outa Katade, Kazuaki IshiharaAbstract:A high-performance enantioselective quaternary ammonium Hypoiodite catalysis was developed for the dearomatization of arenols using oxone as an environmentally benign oxidant. The oxidation of not ...
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ammonium Hypoiodite catalyzed oxidative dearomatizative azidation of arenols
Chemistry Letters, 2019Co-Authors: Muhammet Uyanik, Kohei Nishioka, Kazuaki IshiharaAbstract:The first transition metal-free catalytic oxidative dearomatizative azidation of arenols has been developed using Hypoiodite catalysis with aqueous hydrogen peroxide and trimethylsilyl azide as an ...
Satoshi Minakata - One of the best experts on this subject based on the ideXlab platform.
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intramolecular c h amination of n alkylsulfamides by tert butyl Hypoiodite or n iodosuccinimide
Chemistry: A European Journal, 2021Co-Authors: Kensuke Kiyokawa, Keisuke Jou, Satoshi MinakataAbstract:1,3-Diamines are an important class of compounds that are broadly found in natural products and are also widely used as building blocks in organic synthesis. Although the intramolecular C-H amination of N-alkylsulfamide derivatives is a reliable method for the construction of 1,3-diamine structures, the majority of these methods involve the use of a transition-metal catalyst. We herein report on a new transition-metal-free method using tert-butyl Hypoiodite (t-BuOI) or N-iodosuccinimide (NIS), enabling secondary non-benzylic and tertiary C-H amination reactions to proceed. The cyclic sulfamide products can be easily transformed into 1,3-diamines. Mechanistic investigations revealed that amination reactions using t-BuOI or NIS each proceed via different pathways.
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transition metal free intramolecular c h amination of sulfamate esters and n alkylsulfamides
Chemical Communications, 2019Co-Authors: Kensuke Kiyokawa, Shogo Nakamura, Keisuke Jou, Kohji Iwaida, Satoshi MinakataAbstract:The transition-metal-free intramolecular C–H amination of sulfamate esters using iodine oxidants, tert-butyl Hypoiodite (t-BuOI) and N-iodosuccinimide (NIS) is reported. A method using NIS was also successfully applied to the oxidative cyclization of N-alkylsulfamides.
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oxidative dimerization of hetero aromatic amines utilizing t buoi leading to hetero aromatic azo compounds scope and mechanistic studies
Journal of Organic Chemistry, 2013Co-Authors: Sota Okumura, Youhei Takeda, Chunhsuan Lin, Satoshi MinakataAbstract:A straightforward synthetic method of both symmetric and unsymmetric aromatic azo compounds through an efficient and cross-selective oxidative dimerization of aromatic amines using tert-butyl Hypoiodite (t-BuOI) under metal-free and mild conditions has been developed. This method was also found applicable to the synthesis of heteroaromatic azo compounds. The spectroscopic study indicates the involvement of N,N-diiodoanilines in the oxidative reaction as the key intermediate.
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Oxidative Dimerization of (Hetero)aromatic Amines Utilizing t‑BuOI Leading to (Hetero)aromatic Azo Compounds: Scope and Mechanistic Studies
2013Co-Authors: Sota Okumura, Youhei Takeda, Chunhsuan Lin, Satoshi MinakataAbstract:A straightforward synthetic method of both symmetric and unsymmetric aromatic azo compounds through an efficient and cross-selective oxidative dimerization of aromatic amines using tert-butyl Hypoiodite (t-BuOI) under metal-free and mild conditions has been developed. This method was also found applicable to the synthesis of heteroaromatic azo compounds. The spectroscopic study indicates the involvement of N,N-diiodoanilines in the oxidative reaction as the key intermediate
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oxidative dimerization of aromatic amines using tbuoi entry to unsymmetric aromatic azo compounds
Angewandte Chemie, 2012Co-Authors: Youhei Takeda, Sota Okumura, Satoshi MinakataAbstract:It's all the hype: An oxidative dimerization reaction of aromatic amines utilizing tert-butyl Hypoiodite (tBuOI) under mild reaction conditions leads to aromatic azo compounds. The method allows access to unsymmetric aromatic azo compounds, which are difficult to prepare by conventional synthetic methods, in a selective manner.
Muhammet Uyanik - One of the best experts on this subject based on the ideXlab platform.
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Hypoiodite catalysed oxidative homocoupling of arenols and tandem oxidation cross coupling of hydroquinones with arenes
Chemical Communications, 2021Co-Authors: Muhammet Uyanik, Dai Nagata, Kazuaki IshiharaAbstract:We report the Hypoiodite-catalyzed oxidative C–C homocoupling of arenols to biarenols or biquinones using aqueous hydrogen peroxide as an oxidant. In addition, by combining Hypoiodite catalysis and lipophilic Lewis acid-assisted Bronsted acid catalysis under aqueous conditions, we achieved a tandem oxidation/cross-coupling reaction of hydroquinones with electron-rich arenes. These results highlight the substantial scope of Hypoiodite/acid co-catalysis for use in oxidative coupling reactions.
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Hypoiodite catalyzed chemoselective tandem oxidation of homotryptamines to peroxy and epoxytetrahydropyridoindolenines
Organic Letters, 2020Co-Authors: Muhammet Uyanik, Hiroki Tanaka, Kazuaki IshiharaAbstract:We developed the Hypoiodite-catalyzed tandem dearomative peroxycyclization of homotryptamine derivatives to peroxytetrahydropyridoindolenines under mild conditions. During the course of a mechanistic study, we found that a tandem oxidative cyclization/epoxidation as an unexpected reaction proceeded in the presence of TEMPO as an additive. Intramolecular oxidative aminocyclization of homotryptamines at the C-2 position would give tetrahydropyridoindole, a common intermediate for both reactions. Control experiments suggested that while oxidative coupling with TBHP at the C-3 position might afford peroxyindolenines, a preferential electrophilic addition of TEMPO+, which might be generated in situ by the Hypoiodite-catalyzed oxidation of TEMPO, at C-3 position followed by elimination and epoxidation might give epoxyindolenines. This serendipitous finding prompted us to develop a chemoselective divergent synthesis of peroxy- and epoxyindolenines by simple modification of the reaction conditions.
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Chemoselective oxidative generation of ortho-quinone methides and tandem transformations
Nature Chemistry, 2020Co-Authors: Muhammet Uyanik, Kohei Nishioka, Ryutaro Kondo, Kazuaki IshiharaAbstract:ortho -Quinone methides are useful transient synthetic intermediates in organic synthesis. These species are most often generated in situ by the acid- or base-mediated transformation of phenols that have been pre-functionalized at a benzylic position, or by biomimetic oxidation of the corresponding ortho -alkylphenols with metal oxidants or transition-metal complexes. Here we describe a method for the transition-metal-free oxidative generation of o -QMs from ortho -alkylarenols, using Hypoiodite catalysis under nearly neutral conditions, which can then be applied in one-pot tandem reactions. This method for the chemoselective oxidative generation of ortho -quinone methides may prove superior to previous methods with respect to environmental issues and scope, and can be applied to various tandem reactions such as inter- or intramolecular [4 + 2] cycloaddition, oxa-6π-electrocyclization, conjugate addition and spiroepoxidation. ortho -Quinone methides are highly reactive transient intermediates found in some organic syntheses and biological processes. The generation of these species often requires pre-functionalized substrates and/or metal oxidants, but now the chemoselective oxidative generation of ortho -quinone methides from ortho -alkylarenols has been achieved using Hypoiodite catalysis under nearly neutral conditions.
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high performance ammonium Hypoiodite oxone catalysis for enantioselective oxidative dearomatization of arenols
ACS Catalysis, 2019Co-Authors: Muhammet Uyanik, Takehiro Kato, Naoto Sahara, Outa Katade, Kazuaki IshiharaAbstract:A high-performance enantioselective quaternary ammonium Hypoiodite catalysis was developed for the dearomatization of arenols using oxone as an environmentally benign oxidant. The oxidation of not ...
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ammonium Hypoiodite catalyzed oxidative dearomatizative azidation of arenols
Chemistry Letters, 2019Co-Authors: Muhammet Uyanik, Kohei Nishioka, Kazuaki IshiharaAbstract:The first transition metal-free catalytic oxidative dearomatizative azidation of arenols has been developed using Hypoiodite catalysis with aqueous hydrogen peroxide and trimethylsilyl azide as an ...
Jijun Xue - One of the best experts on this subject based on the ideXlab platform.
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synthesis of γ rubromycin via a new Hypoiodite catalytic oxidative cycloetherification
Organic Letters, 2012Co-Authors: Liping Wei, Jijun Xue, Hongbiao Liu, Wenjing WangAbstract:A new synthesis of γ-rubromycin is presented through a new oxidative, bisbenzannulated spiroketalization as a key step which is catalyzed by an in situ generated Hypoiodite species, developed previously by our group. This key transformation has high efficiency and convenient conditions. This is a new and efficient catalytic application for organohypoiodine reagents.
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new fluoride promoted Hypoiodite catalytic oxidative cycloetherification to aromatic spiroketals
ChemInform, 2012Co-Authors: Wei Wei, Xiaohong Lin, Jijun XueAbstract:Hypoiodide reagents, generated in situ from Bu4NI, catalyze the synthesis of bisbenzannulated spiroketal cores.
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New fluoride-promoted Hypoiodite-catalytic oxidative cycloetherification to aromatic spiroketals
Organic & biomolecular chemistry, 2012Co-Authors: Wei Wei, Xiaohong Lin, Jijun XueAbstract:A new catalytic application of Hypoiodite reagents generated in situ from iodide ions is found, which succeeded in the synthesis of bisbenzannelated spiroketal cores for the first time. Fluoride was proven to be obligatory for this spiroketalization, which is the first fluoride-promoted oxidative cycloetherification to aromatic spiroketals.
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construction of aromatic 5 5 spiroketals via Hypoiodite catalyzed etherification combined in relay cascades
Organic Letters, 2012Co-Authors: Wei Wei, Yao Wang, Jianpeng Yin, Jijun XueAbstract:An approach is developed for the synthesis of bisbenzannelated spiro[5,5]ketals via a catalytic relay reaction cascade involving a new cyclo-etherification, which is prompted by fluoride and catalyzed by the Hypoiodite species generated in situ from irradiative aerobic oxidation of an iodide ion formed in the former step of the reaction cascade.
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Synthesis of (±)-γ-Rubromycin via a New Hypoiodite-Catalytic Oxidative Cycloetherification
2012Co-Authors: Liping Wei, Jijun Xue, Hongbiao Liu, Wenjing WangAbstract:A new synthesis of γ-rubromycin is presented through a new oxidative, bisbenzannulated spiroketalization as a key step which is catalyzed by an in situ generated Hypoiodite species, developed previously by our group. This key transformation has high efficiency and convenient conditions. This is a new and efficient catalytic application for organohypoiodine reagents
Youhei Takeda - One of the best experts on this subject based on the ideXlab platform.
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oxidative dimerization of hetero aromatic amines utilizing t buoi leading to hetero aromatic azo compounds scope and mechanistic studies
Journal of Organic Chemistry, 2013Co-Authors: Sota Okumura, Youhei Takeda, Chunhsuan Lin, Satoshi MinakataAbstract:A straightforward synthetic method of both symmetric and unsymmetric aromatic azo compounds through an efficient and cross-selective oxidative dimerization of aromatic amines using tert-butyl Hypoiodite (t-BuOI) under metal-free and mild conditions has been developed. This method was also found applicable to the synthesis of heteroaromatic azo compounds. The spectroscopic study indicates the involvement of N,N-diiodoanilines in the oxidative reaction as the key intermediate.
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Oxidative Dimerization of (Hetero)aromatic Amines Utilizing t‑BuOI Leading to (Hetero)aromatic Azo Compounds: Scope and Mechanistic Studies
2013Co-Authors: Sota Okumura, Youhei Takeda, Chunhsuan Lin, Satoshi MinakataAbstract:A straightforward synthetic method of both symmetric and unsymmetric aromatic azo compounds through an efficient and cross-selective oxidative dimerization of aromatic amines using tert-butyl Hypoiodite (t-BuOI) under metal-free and mild conditions has been developed. This method was also found applicable to the synthesis of heteroaromatic azo compounds. The spectroscopic study indicates the involvement of N,N-diiodoanilines in the oxidative reaction as the key intermediate
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oxidative dimerization of aromatic amines using tbuoi entry to unsymmetric aromatic azo compounds
Angewandte Chemie, 2012Co-Authors: Youhei Takeda, Sota Okumura, Satoshi MinakataAbstract:It's all the hype: An oxidative dimerization reaction of aromatic amines utilizing tert-butyl Hypoiodite (tBuOI) under mild reaction conditions leads to aromatic azo compounds. The method allows access to unsymmetric aromatic azo compounds, which are difficult to prepare by conventional synthetic methods, in a selective manner.
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Cyclizative Atmospheric CO2 Fixation by Unsaturated Amines with t‑BuOI Leading to Cyclic Carbamates
2012Co-Authors: Youhei Takeda, Sota Okumura, Saori Tone, Itsuro Sasaki, Satoshi MinakataAbstract:A cyclizative atmospheric CO2 fixation by unsaturated amines such as allyl and propargyl amines under mild reaction conditions, efficiently leading to cyclic carbamates bearing a iodomethyl group, have been developed utilizing tert-butyl Hypoiodite (t-BuOI)
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generation of nitrile oxides from oximes using t buoi and their cycloaddition
Organic Letters, 2011Co-Authors: Satoshi Minakata, Sota Okumura, Toshiki Nagamachi, Youhei TakedaAbstract:tert-Butyl Hypoiodite (t-BuOI) was found to be a powerful reagent for the cycloaddition of oximes and alkenes/alkynes, leading to the formation of a variety of isoxazolines or isoxazoles under mild conditions.
