Kyushu University Academic Staff Educational and Research Activities Database
List of Reports
Hiroyuki Morimoto Last modified date:2019.06.08

Lecturer / Biopharmacology, Department of Pharmaceutical Sciences / Department of Chemo-Pharmaceutical Sciences / Faculty of Pharmaceutical Sciences


Reports
1. Kazuhiro Morisaki, Hiroyuki Morimoto, Kazushi Mashima, Takashi Ohshima, Development of direct enantioselective alkynylation of αketoester and α-ketiminoesters catalyzed by phenylbis(oxazoline)Rh(III) complexes, Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry, 10.5059/yukigoseikyokaishi.76.226, 2018.01, Direct catalytic enantioselective alkynylation of carbonyl compounds and imines is one of the most efficient approaches for the synthesis of propargylic alcohols and propargylamines, which are potent building blocks for synthesizing functionalized molecules. While a variety of methods for the reactions with aldehydes and aldimines have been established, the reactions with ketones and ketimines remain underdeveloped due to their reduced reactivity and difficulty in stereocontrol. In this account, we summarized our studies on direct enantioselective alkynylation reaction of α-ketoester and α-ketiminoesters catalyzed by phenylbis(oxazolinephebox)-rhodium(III) complexes, affording enantioenriched propargyl alcohols and propargylamines with a tetrasubsti-tuted carbon stereocenter under proton-transfer conditions. The catalytic system was compatible to a wide range of functional groups, including electrophilic formyl groups, and allowed for the development of an efficient method to access enantioenriched α-CF3-substituted thalidomide analogs. Mechanistic studies revealed that generation of the (alkynyl(phebox)Rh(III) complex from the (diacetatophebox)Rh(III) complex determined the overall reaction rate in the initial stages of the reaction. These results, along with the observed facile exchange of the alkynyl ligand on the (alkynylphebox)Rh(III) complexes, led us to use (trimethylsilylethynylphebox)Rh(III) complexes as a new pre-catalyst. The new catalytic system with (trimethylsilylethynylphebox)Rh (III) precatalysts exhibited enhanced catalytic performance, reduced catalyst loading to as low as 0.5 mol%, and expanded the substrate scope of the reaction with less reactive α-ketiminophos-phonate and cyclic N-sulfonyl α-ketiminoesters..
2. 森崎 一宏, 森本 浩之, 大嶋 孝志, 真島 和志, Direct Enantioselective Alkynylation of α-Ketoesters and α-Ketiminoesters Catalyzed by [Bis(oxazoline)phenyl]rhodium(III) Complexes, Heterocycles, 2017.01.
3. Kazuhiro Morisaki, Hiroyuki Morimoto, Kazushi Mashima, Takashi Ohshima, Direct enantioselective alkynylation of α-ketoesters and α-ketiminoesters catalyzed by [bis(oxazoline)phenyl]rhodium(III) complexes, Heterocycles, 10.3987/REV-16-SR(S)4, 2017, This review summarizes our studies of the direct enantioselective alkynylation of α-ketoesters and α-ketiminoesters catalyzed by [bis(oxazoline)phenyl]rhodium(III) ((phebox)Rh(III)) complexes. The reactions provide chiral α-tetrasubstituted propargyl alcohols and propargylamines under proton-transfer conditions in high yield and with high enantioselectivity. The unique nature of (phebox)Rh(III) complexes allows the reactions to occur in the presence of various functional groups, including an electrophilic aldehyde functionality. Mechanistic studies revealed that the generation of (alkynyl)Rh(III) complexes limited the overall reactivity, which led us to use (trimethylsilylethynyl)(phebox)Rh(III) complexes as efficient pre-catalysts. The use of (trimethylsilylethynyl)(phebox)Rh(III) complexes reduced catalyst loading to as low as 0.5 mol%, and expanded the substrate scope to unprecedented α-ketiminophosphonate and cyclic N-sulfonyl α-ketiminoesters..
4. Hiroyuki Morimoto, Direct catalytic anti-Markovnikov addition reactions of oxygen nucleophiles to simple Alkenes, Yuki Gosei Kagaku Kyokaishi/Journal of Synthetic Organic Chemistry, 10.5059/yukigoseikyokaishi.72.1402, 2014.12, Development of direct catalytic anti-Markovnikov addition reactions of oxygen nucleophiles to simple alkenes is a difficult challenge due to the propensity to form Markovnikov adducts under ordinary reaction conditions. Herein selected recent examples that realize these reactions with high anti-Markovnikov selectivity are summarized..