Kyushu University Academic Staff Educational and Research Activities Database
List of Presentations
TATSUYA UCHIDA Last modified date:2018.06.14

Associate Professor / Division for Arts and Science / Division for Experimental Natural Science / Faculty of Arts and Science


Presentations
1. 内田 竜也, Site-selective Asymmetric C−H Bond Functionalization, The 1st Sino-Japanese Symposium on Catalysis for Precision Synthesis, 2018.05.
2. 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..
3. 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..
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5. Asymmetric Baeyer-Villiger Oxidation Using Metallosalen Complex as Catalyst.
6. Asymmetric Aziridination Using Azide Compounds as Nitrene Precursor in the Presence of Robust Ru(salen) Complex.