Efficient reductive Claisen rearrangement of prop-2'-enyloxyanthraquinones and 2'-chloroprop-2'-enyloxyanthraquinones with iron powder in ionic liquids

Abstract

A rapid and selective iron-mediated reductive Claisen rearrangement of various prop-2'-enyloxyanthraquinones and 2'-chloroprop-2'-enyloxyanthraquinones to 1-hydroxy-2-(prop-2'-enyl)anthraquinones and anthrafurandiones is presented. All reactions are carried out in a mixture of ionic liquids, [Bzmim]Cl (1-benzyl-3-methylimidazolium chloride) and [Hmim]BF$_{4}$ (1-methylimidazolium tetrafluoroborate), in short reaction times (5-35 min). Our study showed that 1-(prop-2'-enyloxy)anthraquinone is more active than 1-(2'-chloroprop-2'-enyloxy)anthraquinone to perform this rearrangement.