Fluorenone-4-carboxylic acid synthesis

Patra et al. described the regiospecific synthesis of benz[a]anthracene-5,6-dione 9 and their efficient conversion to benzo[h]fluorenones 11 through the carboxylic acid 10. The transformation of 9 to 10 has been effected by benzilic acid rearrangement employing the method of Toda et using powdered KOH in dioxane. Several other conditions such as NaOH in water, KOH in a mixture of ethanol and water, KOH in a mixture of dioxane and water and NaOEt in ethanol did not give satisfactory results. 

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