SYNTHESIS OF NEOLIGNANS VIA A PROPOSED BIOSYNTHETIC INTERMEDIATE - TOTAL SYNTHESIS OF (+ -)-FUTOENONE/

The attempted spectroscopic observation of a quinone methide proposed to be an intermediate in the biosynthesis of neolignans is reported. T he results afforded substantial indirect evidence for the formation of quinone methide 3. The synthesis of racemic bicyclo[3.2.1]octenedione 22, a natural product, is proposed to occur through a similar quinone methide intermediate. The synthesis of (+/-)-futoenone via a benzylic cation intermediate related to quinone methide 3 is reported. The res ults provide support for Gottlieb's proposal that several different ne olignans arise from a common biosynthetic precursor. The efficient syn thesis of (+/-)-futoenone and related spiro[5.5]undecanoids using a Bu chi quinone ketal cycloaddition is also described.