A concise total synthesis of biologically active frutinones via tributylphosphine-catalyzed tandem acyl transfer-cyclization

A concise and step-economical total synthesis of biologically active frutinones has been achieved. Tributylphosphine (PBu3) efficiently induced the tandem acyl transfer-cyclization of carbonates 5 to afford 3-methoxycarbonylflavone derivatives 4 in excellent yields. Finally, concomitant deprotection and lactonization under acidic conditions furnished the desired frutinones A (1a), B (1b), and the proposed structure of frutinone C (1c).

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