|TATSUYA UCHIDA||Last modified date：2019.06.14|
Associate Professor / Division for Arts and Science / Division for Experimental Natural Science / Faculty of Arts and Science
|1.||Daiki Doiuchi, Hiroki Hayashi, Tatsuya Uchida, Ruthenium-Catalyzed 3° C–H Bond Selective Hydroxylation, 6th Japan–UK Symposium on Asymmetric Catalysis, 2018.11.|
|2.||Tatsuya Uchida, Asymmetric C–H Functionalization, 6th Japan–UK Symposium on Asymmetric Catalysis, 2018.11, Carbon–hydrogen bonds are ubiquitous and abundant in organic molecule. If that C–H bond can be directly converted to desired function group with stereo- and site-selective manner, C– H bond functionalization would really strong and efficient tool in organic synthesis. Recently, we found that ruthenium-salen complexes are efficient catalyst for nitrene and oxo transfer reactions using highly atom-economic oxidants such as azide and dioxygen.
(OC)ruthenium(II)-salen complex decompose azide compounds to corresponding nitrene intermediates with co-producing nitrogen gas as the by-product. Obtained ruthenium-nitrene can insert benzylic and allylic C–H bond with excellent site- and stereo-selective manner. Interestingly, ruthenium-catalysed C–H amination undergoes exclusively at methylene C–H bond on ethyl group. 1
On the other hand, (aqua)ruthenium(III) complex can activate dioxygen to superoxide intermediate via single electron transfer (SET). Obtained superoxide delocalized radical cation intermediate.2 This mechanism suggests that, arenols could be oxidized to the electrophilic radical intermediate and then converted to the desired bis(arenol)s. Based on this suggestion, we conducted the oxidative coupling of arenols using dioxygen as a hydrogen accepter. Under ruthenium-catalyzed aerobic conditions, arenols can converted to bis(arenol)s with good to high enantioselectivity. Under that conditions, C3-substituted 2-naphthols using C7-substituted 2-naphthols or phenol derivatives gave the cross-coupling products with good to high chemoselectivity, irrespective with electron nature of each arenols..
|3.||Hiroki Hayashi, Takamasa Ueno, Tatsuya Uchida, Ruthenium-Catalyzed Enanatioselective Oxidative Cross-Coupling of 2-Naphthols, The Fourth International Symposium On C–H Activation, 2018.08.|
|4.||Yuki Yamakawa, Takashi Ikuta, Hiroki Hayashi, Tatsuya Uchida, Highly Site-selective C–H Insertion via Iridium-Carbene Intermediate, The Fourth International Symposium on C–H Activation, 2018.08.|
|5.||Tatsuya Uchida, Asymmetric Oxidative Cross-Coupling of Arenols, The 13th International Symposium on Activation of Dioxygen and Homogeneous Oxidation Catalysis, 2018.06.|
|6.||内田 竜也, Site-selective Asymmetric C−H Bond Functionalization, The 1st Sino-Japanese Symposium on Catalysis for Precision Synthesis, 2018.05.|
|7.||内田 竜也, Activation of Molecular Oxygen and Catalytic Asymmetric Aerobic Oxidation, 第1回精密制御反応場国際シンポジウム, 2016.07, Molecular oxygen (O2) is an ubiquitous, abundant, and highly atom economic oxidant on the earth. However, most of O2 activation required heating and/or pressurizing conditions or the addition of co-reductant, unfortunately. Stereoselectivities of these oxidations are insufficient. On the other hand, typical biological oxidation proceeded with complete stereoselectivity albeit with consuming 2H+ and 2e- and producing water as a waste material. Thus, development of new methodology for O2 activation has been strongly required. Herein, we presented ruthenium-catalyzed highly enantioselective aerobic oxidation such as epoxidation and oxidative kinetic resolution of alcohol.Under aqueous conditions, ruthenium-salen complexes can activate O2 to active oxygen spices such as corresponding superoxide and oxo spices via single-electron-transfer (SET) and proton-coupled- electron-transfer (PCET) with water mediation, and catalyze epoxidation of trans- -methylstyrene derivatives with good to high enantioselectivity (up to 95% ee).1b On the other hand, under alcoholic conditions, racemic sec-alcohol was oxidized with high enantiomer differentiation (krel = up to 60).1a It was noteworthy that ruthenium-salen complexes catalyzed aerobic oxidations are proceed under ambient conditions without any activation methods..|
|8.||内田 竜也, Development of Catalytic C-C Bond Formation, I2CNER International Workshop -Natural and Chemical Catalysts for Technology-, 2017.02, C-H bond functionalization via carbene transfer reaction is one of strong and useful tool for the construction of carbon framework and has garner much attention. However, C-H bond, which is ubiquitous and abundant in organic molecule, is still difficult to convert desired function group at well. Herein, we found that (aryl)iridium(salen) complexes are efficient catalysis in C-H functionalization.1 (Aryl)iridium complex can decompose -aryl- -dizaoacetates to desired carbene intermediates and convert benzylic, allylic, and propargylic C-H bond to the corresponding C-C bond with excellent diastereo- and enantio-selectivities. Furthermore, iridium-catalyzed C-H insertion reactions showed interesting site-selectivity. That reaction carried out at only methylene C-H bond on ethyl group..|
|10.||Asymmetric Baeyer-Villiger Oxidation Using Metallosalen Complex as Catalyst.|
|11.||Asymmetric Aziridination Using Azide Compounds as Nitrene Precursor in the Presence of Robust Ru(salen) Complex.|