Patent ID: 8324411

Claim:
A process for the preparation of 4,5-bis(acetyloxy)-9,10-dihydro-9,10-dioxo-2-anthracene carboxylic acid of formula (I) and its salts, which comprises: a) reacting a protected aloe-emodin of formula (II) in which Pr is a benzyl or substituted benzyl group not hydrolysable in an aqueous environment, with an oxidising system which comprises the radical 2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl of formula (III): where R 1 is chosen from H, OH, O-alkyl and O-alkanoyl, in the presence of an alkaline or alkaline-earth chlorite and an alkaline or alkaline-earth hypochlorite, in an appropriate solvent, to give the compound of formula (IV) b) replacing the Pr protector groups with acetyl groups and optionally isolating and purifying the compound of formula (I) thus obtained.