6,7-Dimethyl-3,4-benzotropolone (III; R1= H, R2= Me) and the related 5-hydroxy-3,4-benzotropolones (III; R1= OH, R2= Me) and (III; R1= OH, R2= H) are formed in good yield when derivatives of 2-acetyl-3,4-dihydronaphthalen-1 (2H)-one ate treated with zinc in acetic acid. The reductive ring expansions are discussed in terms of cyclopropanediol intermediates.
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