研究テーマ

我々の研究は以下の三つの軸で進んでいる.
1)精密な触媒設計により基質を認識する反応場を構築し,配向基を有しない単純アレーンの位置選択的直接官能基化反応を実現することを目的としている.
2)合成化学の持続的発展を目指し,普遍金属触媒および試薬(有機ナトリウム試薬)の開発に取り組んでいる.
3)開発した合成法は,機能性分子および医薬品分子合成への応用を目指している.

最近の研究成果

Ligand-enabled site selective C–H functionalization
ACS Catal.  2021, 11, 5968–5973.   link
  Fluoroarenes are important compounds for drug discovery, and late-stage selective functionalization of these compounds allows structure-bioactivity relationship studies. We developed a new terpyridine ligand, which in combination with an iridium salt catalyzes the stoichiometric borylation of various fluoroarenes with high ortho-selectivity to fluorine. The catalytic system tolerates sensitive functional groups, and thus could be used for the selective functionalization of a complex drug molecule such as haloperidol. Preliminary mechanistic studies by experiment and calculation suggested that the terpyridine ligand does not coordinate iridium through the typical N, N, N-coordination mode, but instead undergoes rollover cyclometalation to generate an N, N, C-coordinated iridium complex.
 
Synthesis of organosodium compounds through halogen/sodium exchange
Commun. Chem. 20214, 76.     link
Review:  Synthesis  2021, DOI:  10.1055/a-1478-7061.  link
  Halogen–lithium exchange has been extensively used in organic synthesis because it allows rapid preparation of a large variety of organolithium compounds from (hetero)aryl or alkenyl bromides or iodides, typically using butyllithium or tert-butyllithium under cryogenic conditions. From a sustainability point of view, there is a growing demand for alternatives to the less abundant and increasingly expensive lithium. Sodium is an attractive candidate, but attempts at halogen–sodium exchange using alkylsodiums such as butylsodium and pentylsodium have met with significant challenges, such as low yields and formation of byproducts.
  We discovered that the use of a primary and bulky alkylsodium lacking β-hydrogens retards undesired reactions and enables efficient halogen–sodium exchange. The alkylsodium is readily prepared in situ from neopentyl chloride and an easy-to-handle sodium dispersion, and allows us to prepare a large variety of (hetero)aryl- and alkenylsodium compounds including tri- and tetrasodioarenes, many of them previously inaccessible by other methods.
  We believe that this reaction has the potential to replace the textbook halogen–lithium exchange, and open new frontiers for establishing organosodium-based organic chemistry.