翻訳と辞書
Words near each other
・ Modified Overt Aggression Scale
・ Modified pressure
・ Modified Rankin Scale
・ Modified Richardson iteration
・ Modified risk tobacco product
・ Modified starch
・ Modified Stave Notation
・ Modified stock car racing
・ Modified Toy Orchestra
・ Modified Transverse Mercator coordinate system
・ Modified triadan system
・ Modified universalism
・ Modified vaccinia Ankara
・ Modified waterfall models
・ Modified Wigner distribution function
Modified Wittig-Claisen tandem reaction
・ Modifier
・ Modifier key
・ Modifier letter apostrophe
・ Modifier letter double apostrophe
・ Modifier letter left half ring
・ Modifier letter right half ring
・ Modifier letter ring above
・ Modifier Tone Letters
・ Modify Watches
・ Modig
・ Modiga agenter
・ Modiga mindre män
・ Modigliana
・ Modigliana Cathedral


Dictionary Lists
翻訳と辞書 辞書検索 [ 開発暫定版 ]
スポンサード リンク

Modified Wittig-Claisen tandem reaction : ウィキペディア英語版
Modified Wittig-Claisen tandem reaction

Modified Wittig-Claisen tandem reaction is a cascade reaction that combines Wittig reaction and Claisen rearrangement together. The Wittig reaction generates the allyl vinyl ether intermediate that further participates in a Claisen rearrangement to generate the final γ, δ-unsaturated ketone or aldehyde product (Figure "Modified Wittig-Claisen tandem reactions").
The modified Wittig-Claisen tandem reaction has been a useful retrosynthetic strategy and has been applied to the synthesis of various complex natural products and other molecules. This reaction is especially useful for construction of cyclic ketones with double bond at the γ, δ-position. Paquette and co-workers reported the synthesis of 4-cyclooctenone structure by expanding the six-membered ring of a 2-cyclohexanone structure.〔Philippo, C. M. G.; Vo, N. H.; Paquette, L. A. J. Am. Chem. Soc. 1991, 113, 2763.〕 The key step was a tandem process that combines Tebbe olefination (a reaction similar to Wittig reaction) with Claisen rearrangement (Figure "Application of modified Wittig-Claisen tandem reactions for construction of 4-cyclooctenone structure").
Tandem Wittig-Claisen reaction has also been applied to the construction of the spiro() ring system in natural products such as horsfiline.〔Kulkarni, M. G.; Dhondge, A. P.; Chavhan, S. W.; Borhade, A. S.; Shaikh, Y. B.; Birhade, D. R.; Desai, M. P.; Dhatrak, N. R. Beilstein J. Org. Chem. 2010, 6, 876.〕 The synthesis started with a simple o-nitrobenzaldehyde. A Wittig-Claisen reaction sequence converted the starting material to a 4-pentenal derivative that could serve as a versatile intermediate for the synthesis of various natural products. In this case, the 4-pentenal derivative was further converted to the natural product horsfiline, the active ingredient of a traditional herbal medicine with analgesic effects.
==References==

*
*
*
*

抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)
ウィキペディアで「Modified Wittig-Claisen tandem reaction」の詳細全文を読む



スポンサード リンク
翻訳と辞書 : 翻訳のためのインターネットリソース

Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.