Rare Example of Nucleophilic Substitution at Vinylic Carbon with Inversion: Mechanism of Methyleneaziridine Formation by Sodium Amide Induced Ring Closure Revisited
作者:Jason J. Shiers、Michael Shipman、Jerome F. Hayes、Alexandra M. Z. Slawin
DOI:10.1021/ja0482684
日期:2004.6.1
(Z)-2-bromobut-2-enylamines by the pendant nitrogen atom leads to 2-ethyleneaziridines by way of stereochemical inversion at the vinylic carbon atom. The stereochemistry of the products is unambiguously established by X-ray crystallography performed on two derivatives. These cyclizations represent some of the first examples of substitution with inversion in unactivated vinylic substrates. In conjunction
(E)- 和 (Z)-2-bromobut-2-enylamines 的 C-Br 键被侧氮原子的分子内亲核取代通过在乙烯基碳原子上的立体化学反转产生 2-亚乙基氮丙啶。产物的立体化学是通过对两种衍生物进行的 X 射线晶体学明确确定的。这些环化代表了在未活化的乙烯基底物中进行反转取代的一些第一个例子。结合额外的氘标记实验,该反应的公认机制被证明是有缺陷的。
Generation and electrophilic substitution reactions of 3-lithio-2-methyleneaziridines
作者:Cyril Montagne、Natacha Prévost、Jason J. Shiers、Gildas Prié、Sabitur Rahman、Jerome F. Hayes、Michael Shipman
DOI:10.1016/j.tet.2006.06.083
日期:2006.9
2-Methyleneaziridinyl anions can be produced by selective deprotonation of the parent aziridine at C-3 using sec-BuLi/TMEDA. Subsequent reaction with a wide variety of electrophiles including MeI, ICH2CH2CH2CH2Cl, PhCH2Br, allyl bromide, Me3SiCl, Bu3SnCl, PhCHO and Ph2CO provides the corresponding C-3 substituted derivatives in moderate to good yields (43-91%). In the case of homochiral methyleneaziridines bearing an (S)-alpha-methylbenzyl group on nitrogen, high levels of diastereocontrol (up to 90%de) can be achieved in this lithiation/alkylation sequence. (c) 2006 Elsevier Ltd. All rights reserved.