intermediates generated from electrophilic cyclizations for tandem C–C bond construction is a challenging task but constitutes an excellent tool for constructing complex motifs from simpler substrates. We realize herein such a cyclative annulation of alkynyl-oxime ethers with maleimides for the facile construction of isoxazole-phthalimide hybrid motifs throughPd(II) catalysis. This protocol features excellent
利用亲电环化产生的有机钯中间体进行串联 C-C 键构建是一项具有挑战性的任务,但它是从更简单的底物构建复杂基序的绝佳工具。我们在此实现了炔基肟醚与马来酰亚胺的环化,以便通过 Pd(II) 催化轻松构建异恶唑-邻苯二甲酰亚胺杂化基序。该方案具有出色的 C-H 选择区域选择性、广泛的底物范围、良好的官能团耐受性和可扩展性。必要的 KIE 和标记研究可以深入了解反应机制。
Iron(III) Chloride/Diorganyl Diselenides: A Tool for Intramolecular Cyclization of Alkynone <i>O</i>-Methyloximes
作者:Adriane Sperança、Benhur Godoi、Gilson Zeni
DOI:10.1021/jo302770g
日期:2013.2.15
This report describes the synthesis of 4-organoselenylisoxazoles via FeCl3/RSeSeR-mediated intramolecular cyclization of allcynone O-methyloximes. The optimized conditions allowed the cyclization to proceed at room temperature under ambient atmosphere, and the reaction requires a short time to be completed. The reaction conditions tolerated neutral, electron-donating and electron-withdrawing groups present in both substrates, alkynone O-methyloximes and diorganyl diselenides. Treatment of 4-organoselenylisoxazoles with n-butyllithium, followed by trapping with electrophiles, furnished the functionalized isoxazoles in good yields. The obtained products also proved to be suitable substrates for the preparation of 4-bromoisoxazoles via Br/Se exchange reaction.