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タイトル: | Critical profiles of chiral diether-mediated asymmetric conjugate aminolithiation of enoate with lithium amide as a key to the total synthesis of (−)-kopsinine |
著者: | Harada, Shingo Sakai, Takeo Takasu, Kiyosei https://orcid.org/0000-0002-1798-7919 (unconfirmed) Yamada, Ken-ichi Yamamoto, Yasutomo Tomioka, Kiyoshi |
著者名の別形: | 原田, 慎吾 山田, 健一 山本, 康友 富岡, 清 |
キーワード: | Total synthesis One-pot Lithium Asymmetric reaction Heterocycles |
発行日: | Apr-2013 |
出版者: | Elsevier Ltd. |
誌名: | Tetrahedron |
巻: | 69 |
号: | 15 |
開始ページ: | 3264 |
終了ページ: | 3273 |
抄録: | Chiral diether-mediated asymmetric aminolithiation of indolylpropenoate with lithium amide in toluene at -78 °C for 15 min gave, after aqueous ammonium chloride quench, the corresponding conjugate addition product with 97% ee in 89% yield. If hydrogen chloride in methanol was selected as a quencher, however, aminolithiation at -78 °C for 3 h gave the corresponding adduct with 97% ee in 54% yield, along with recovery of the starting enoate in 39% yield. Based on this finding of an incomplete and slow reaction at -78 °C, the aminolithiation conditions were optimized to be at -60 °C for 15 h and subsequent enolate trap with alkyl halide upon an addition of DMPU afforded the desired aminoalkylation product with 98% ee in 89% yield. Further approach toward total synthesis of (−)-kopsinine was carried out by examining asymmetric aminolithiation with N-hydroxyethylamine equivalent, one-pot piperidine formation, and Claisen condensation. |
著作権等: | © 2013 Elsevier Ltd. この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。 This is not the published version. Please cite only the published version. |
URI: | http://hdl.handle.net/2433/173087 |
DOI(出版社版): | 10.1016/j.tet.2013.02.035 |
出現コレクション: | 学術雑誌掲載論文等 |
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