We are developing novel transition metal catalysts that can promote efficient transformations of functional groups containing multiple bonds in organic molecules using hydrosilanes as a reducing reagent.

Outcome：

2024
We have already reported that the combination of Pd/C with Cu(acac)2 or Cu(OAc)2 acts as an efficient catalyst system for the preparation of alkyl silyl acetals by partial rsilane-eduction of esters using TMDS, and allylation reaction of aliphatic silyl asetals proceeds smoothly in the presence of Lewis acids. In this study, we found that nucleophilic substitution of lactone-derived cyclic silyl asetals also proceeds by using allyl silanes and ketene silyl asetals as nucleophiles without ring opening reactions.

2023
We have previously reported that the combination of Pd/C with Cu(acac)2 or Cu(OAc)2 acts as an efficient catalyst system for the conversion of esters to alkyl silyl acetals. These alkyl silyl acetals formed was converted effectively to the corresponding ethers by the addition of Lewis acids under low temperature. During the course of our continuous studies on the deoxygenative reduction of esters, desired ether compounds were obtained directly under mild conditions by Pd/C-Cu(OTf)2 in dimethoxyethane system.

2022
We have previously reported that the combination of Pd/C with Cu(acac)2 or Cu(OAc)2 acts as an efficient catalyst system for the conversion of esters to alkyl silyl acetals. During the course of our continuous studies on the half reduction of esters, zero-valent Pt species and/or Ag salts are also effective towards the present reaction.

2019
Combination of PdCl2 with 1,1,3,3-tetramethyldisiloxane in the presence of activated carbon was found to be an effective catalyst system for the cleavage reaction of C–O bond of O–t-Bu moieties. The present catalytic reaction offers a practical method for the deprotection of tert-butyl esters, tert-butyl ethers, O–Boc, and N–Boc derivatives under mild conditions. The addition of activated carbon in the reaction mixture was proved to be crucial for not only sustaining the catalytic activity but also trapping the palladium species after the reaction.

We are developing novel methods for synthesizing not only heterogeneous metal cluster catalysts supported on carbon materials and metal oxides but also soluble metal cluster catalysts that can promote efficient hydrogenation reactions.

Outcome：

2024
We have previously reported that carbon nanofiber-supported Ru clusters, prepared by thermal decomposition of Ru3(CO)12, show high catalytic activity and durability in the arene hydrogenation, but harsh reaction conditions were required for generating catalytically active species. During the course of our continuous studies on the supported Ru clusters, we found that catalytically active Ru clusters are generated under mild conditions by using Ru(II) complex bearing acetate ligand as a precursor, and Ru/ZrO2 acts as effective catalyst for hydrogenation of arenes having epoxide group remaining intact.

2023
We have previously reported thet Pd(OAc)2 on ZrO2 was easily converted to the corresponding Pd clusters under mild conditions, and these Pd clusters formed showed the catalytic activity towards hydrogenation of imino- group under atmospheric hydrogen. During the course of our continuous studies on the metal oxides-supported Pd clusters, we found that Pd clusters derived from diphenoxyimino Pd complex shows high catalytic activity towards alkenyl moieties but reduction of nitro groups did not proceed. The hydrogenation activity increased by using TiO2 as a support.

2022
Combination of Karstedt’s catalyst or Pt(dba)2 [dba: dibenzylideneacetone] with activated carbon was found to be an efficient catalyst system for the arene hydrogenation of a variety of functionalized aromatic compounds. The reaction proceeds at ambient temperature under atmospheric hydrogen pressure to afford the corresponding carbo- and heterocyclic compounds in good to high yields without contamination of the metallic species. The addition of activated carbon in the reaction mixture was proved to be crucial for not only sustaining the catalytic activity but also trapping the platinum species effectively after the reaction. Similar sustaining effect was observed by the addition of vinyl siloxane derivatives.

本研究では,「究極の嵩高さ」である三級炭素型保護基に着目し，「四級炭素に対する置換反応(保護)」と「除去困難なt-Bu基の脱保護反応」を融合させ，三級炭素型保護基の選択的保護と脱保護手法の確立や多官能性対称分子に対する非対称化手法を確立することで，より実践的な物質合成プロセスに応用展開することが目的である．

Outcome：

2024
アルコールおよびフェノール誘導体を基質とした立体的に嵩高い第三級α－ハロアミドに対するハロゲン部位での置換反応が，既に報告されている手法と比べてより効率的に進行することが明らかとなり，この結果はα－ハロアミドが水酸基のよい三級炭素型保護基として利用できることを示す結果である．また，三級炭素であるtert-ブチル基で保護されたエステルおよびエーテル化合物の脱保護反応についても金属触媒とヒドロシランを組合わせた反応により，良好な結果が得られている．これらの結果を基に，現在論文執筆中である．