title: Syntheses of Anthracenones. 3. Revised Preparative Route to 10-Benzoyl-1,8-dihydroxy-9(10H)-anthracenones.
abstract: The acylation of anthralin (1,8-dihydroxy-9(10H)-anthracenone) with acetylsalicylic acid chloride in toluene and collidine was found to give the O-acylated product, rather than 10-(acetylsalicyl)anthralin. A procedure is described for benzoylation of anthralin in the 10-position which involves reaction of 1,8-diacetoxy-9(10H)-anthracenone with benzoyl chloride and sodium hydride in THF followed by hydrolysis of an intermediate enol ester. Furthermore, when benzoyl chloride and DMF were used for the acylation of anthralin, a Vilsmeier-type reaction was observed leading to a novel enamine derivative of anthralin which was hydrolyzed or benzoylated to an enol or enol ester, respectively.
authors.affiliation: Institut für Pharmazie, Pharmazeutische Chemie I, Universität Regensburg, D-93040 Regensburg, Germany.
authors.forename: Helge
authors.initials: H
authors.lastname: Prinz
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wiegrebe
authors.forename: Klaus
authors.initials: K
authors.lastname: Müller