Friedel−Crafts Reactions of 2,2-Difluorocyclopropanecarbonyl Chloride: Unexpected Ring-Opening Chemistry
作者:William R. Dolbier、Eric Cornett、Henry Martinez、Wei Xu
DOI:10.1021/jo200423y
日期:2011.5.6
3-difluoropropyl ketones. The ring-opened product was formed exclusively, and therefore the reaction may be synthetically useful when relatively unreactive arene substrates such as benzene, toluene, and p-xylene are used. No conditions were found where ring-intact products could be formed exclusively when using substituted benzenes as substrates, with the very reactive substrate thiophene being most selective in that
2,2-二氟环丙烷羰基氯与各种芳烃的Friedel-Crafts反应未导致预期的芳基2,2-二氟环丙基酮的直接形成。取而代之的是,根据芳烃的反应性,反应通过不同程度地进行,该反应通过最初形成的酰基离子的明显重排而形成新的芳基3-氯-3,3-二氟丙基酮。开环产物仅形成,因此当相对不活泼的芳烃底物(例如苯,甲苯和对苯二甲酸)反应时,该反应可能在合成上有用使用了二甲苯。在使用取代的苯作为底物时,没有发现仅能形成环完整产物的条件,就这一点而言,反应性极强的底物噻吩具有最高的选择性,有利于环完整产物3,其选择性为98:2。检查了开环的区域选择性并将其与其他相关系统进行了计算比较。