Functionalization of anthracene: A selective route to brominated 1,4-anthraquinones

Abstract

SummaryEfficient and stereoselective syntheses are described for the preparation of 2,3,9,10-tetrabromo-1,4-dimethoxy-1,2,3,4-tetrahydroanthracenes 7, 8 and the corresponding 1,4-diol 17 by silver ion-assisted solvolysis of hexabromotetrahydroanthracene 6. Base-promoted aromatization of 7 and 8 afforded synthetically valuable tribromo-1-methoxyanthracenes 10 and 11. The reaction of 17 with sodium methoxide generated tribromodihydroanthracene-1,4-diol 27, whose oxidation with PCC gave 2,9,10-tribromoanthracene-1,4-dione (28). Therefore a selective and efficient method was developed for the preparation of compound 28 starting from 9,10-dibromoanthracene (1), in a simple four-step process. Compounds 10 and 11, and diol 27 constitute key precursors for the preparation of functionalized substituted anthracene derivatives that are difficult to prepare by other routes. The studies also reveal the broad range of reactivity and selectivity of the stereoisomeric anthracene derivatives.

Regiodefined synthesis of brominated hydroxyanthraquinones related to proisocrinins

“…Anthraquinones constitute the largest group of naturally occurring quinones [ 1 – 5 ]. Isolated mainly from fungal sources, they display a wide range of biological activities which include anti-inflammatory, antifungal, antiparasidal, and cytotoxic properties [ 6 – 11 ]. Anthraquinones are well-known as colorants in foods, drugs, and textile industries.…”