Marschalk reaction of leucoquinizarin (2) with readily obtainable 4-bromo-2-acetoketal-1-butyraldehyde (3), from ethyl acetoacetate or acetone, gave in one step 4-demethoxy-7, 9-dideoxydaunomycinone (1a) in 60% yield.
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AYYANGAR et al. (1987) studied this question.
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