Friedel-Crafts Cyclization of 1,1-Difluoroalk-1-enes: Synthesis of Benzene-Fused Cyclic Ketones via α-Fluorocarbocations
作者:Junji Ichikawa、Hideharu Jyono、Takao Kudo、Masaki Fujiwara、Misaki Yokota
DOI:10.1055/s-2004-834910
日期:——
1,1-Difluoroalk-1-enes bearing a phenyl group at the C-3, -4, or -5 position, readily obtained from 2,2,2-trifluoroethyl p-toluenesulfonate, are treated with FSO3H·SbF5 to undergo Friedel-Crafts cyclization in (CF3)2CHOH. The cyclization takes place via α-fluorocarbocations, followed by spontaneous hydrolysis of the C-F bond to afford bicyclic ketones including a five, six, or seven-membered ring in good yield.
1,1-二氟烷基-1-烯在 C-3、-4 或 -5 位上带有一个苯基,很容易从 2,2,2-三氟乙基对甲苯磺酸酯中获得,经 FSO3H-SbF5 处理后,在 (CF3)2CHOH 中发生 Friedel-Crafts 环化反应。环化是通过δ-氟碳化合物进行的,随后 C-F 键自发水解,从而得到双环酮,包括五元环、六元环或七元环,收率很高。