Steganolide

An oxidative bond formation between aromatic carbons was described using ruthenium dioxide as the catalyst (Eq. 73).205 in a mixture of dichloromethane, trifluoroacetic acid, and anhydride, the open precursor is cyclized to a steganolide. Sonication permits high yields with only 1.1 equiv. of the catalyst, while twice the amount is required under stirring. 

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