In contrast to the synthesis of 2a, the subsequent oxidation to 3a required considerable optimization. Initially, we followed a protocol reported by Boldt et al., which relies on crystallization of 3a from the reaction medium at room temperature and additionally requires extraction and crystallization steps to improve the yield to 71%. Unfortunately, we did not observe any crystallization of 3a at room temperature (also storing at -18°C overnight just afforded small amounts of precipitate). As we wanted to simplify the protocol anyways, we decided to directly evaporate the reaction solvent as well as volatile by-products instead of storing the reaction for crystallization. The resulting solid was then recrystallized from 1,4dioxane affording tetrone 3a as red needles. Rapid weathering prevented analysis of the crystal structure, but NMR spectroscopy confirmed the purity, except for some 1,4-dioxane, which disappears during storage or when heating the solid, as was observed before. Very good yields of 85% were obtained. Our other target compound, 1,4,5,8-anthracenetetrone 3b, can be prepared by oxidation of 1,4,5,8-tetrahydroxyanthracene using freshly prepared silver oxide, but the yields of this -5-reaction (and the five reactions to prepare the tetrahydroxyanthracene) were reported to be unsatisfactory by Miller et al. Instead, they suggest to oxidize 5,8-dimethoxy-1,4-anthraquinone, which they prepared in a sequence of seven reactions. Obviously, both routes do not comply with our aims of high yields and low work load.