The Synthesis of Hallachrome Leucotriacetate (2,7,8-Triacetoxy-1-methoxy-3-methylanthracene)

Abstract

The synthesis of 2,7,8-triacetoxy-1-methoxy-3-methylanthracene (30), a derivative of hallachrome (7-hydroxy-8-methoxy-6-methylanthracene-1,2- quinone ) (1), the red pigment of the marine worm Halla parthenopeia ( Delle Chiaje ), is described. The key step in the synthesis relied on the alkylation of the aryl cuprate derived from the oxazoline (13) with the benzyl bromide (19), thus ultimately providing the benzylbenzoic acid (25) and thence the anthracene (30).