Asymmetric Hydrogenation of Isoxazolium Triflates with a Chiral Iridium Catalyst

DOI Web Site Web Site 被引用文献1件 参考文献101件
  • Ryuhei Ikeda
    Department of Chemistry, Faculty of Science and International Research Center for Molecular Systems (IRCMS) Kyushu University 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan
  • Ryoichi Kuwano
    Department of Chemistry, Faculty of Science and International Research Center for Molecular Systems (IRCMS) Kyushu University 744 Motooka, Nishi-ku Fukuoka 819-0395 Japan

抄録

<jats:title>Abstract</jats:title><jats:p>The iridium catalyst [IrCl(cod)]<jats:sub>2</jats:sub>–phosphine–I<jats:sub>2</jats:sub> (cod=1,5‐cyclooctadiene) selectively reduced isoxazolium triflates to isoxazolines or isoxazolidines in the presence of H<jats:sub>2</jats:sub>. The iridium‐catalyzed hydrogenation proceeded in high‐to‐good enantioselectivity when an optically active phosphine–oxazoline ligand was used. The 3‐substituted 5‐arylisoxazolium salts were transformed into 4‐isoxazolines with up to 95:5 enantiomeric ratio (e.r.). Chiral <jats:italic>cis</jats:italic>‐isoxazolidines were obtained in up to 89:11 e.r., with no formation of their <jats:italic>trans</jats:italic> isomers, when the substrates had a primary alkyl substituent at the 5‐position. The mechanistic studies indicate that the hydridoiridium(III) species prefers to deliver its hydride to the C5 atom of the isoxazole ring. The hydride attack leads to the formation of the chiral isoxazolidine via a 3‐isoxazoline intermediate. Meanwhile, in the selective formation of 4‐isoxazolines, hydride attack at the C5 atom may be obstructed by steric hindrance from the 5‐aryl substituent.</jats:p>

収録刊行物

被引用文献 (1)*注記

もっと見る

参考文献 (101)*注記

もっと見る

関連プロジェクト

もっと見る

キーワード

問題の指摘

ページトップへ