Tf2O-catalyzed Friedel–Crafts alkylation to synthesize dibenzo[a,d]cycloheptene cores and application in the total synthesis of Diptoindonesin D, Pauciflorial F, and (±)-Ampelopsin B

By using Tf2O as a catalyst, we have developed a protocol for the preparation of various dibenzo[a,d]cycloheptene cores via Friedel–Crafts alkylation. Using this method as the key step, we also present concise and useful routes to synthesize the natural products Diptoindonesin D, Pauciflorial F, and (±)-Ampelopsin B. Notably, this process exhibited following very attractive features: (i) the process is metal free, with only catalytic amounts of Tf2O being employed, and (ii) the process is simple and environmentally conscious, avoiding the use of excess amounts of base, oxidant, or other additives.

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