Sr. Angle et Kd. Turnbull, SYNTHESIS OF NEOLIGNANS VIA A PROPOSED BIOSYNTHETIC INTERMEDIATE - TOTAL SYNTHESIS OF (+ -)-FUTOENONE/, Journal of organic chemistry, 58(20), 1993, pp. 5360-5369
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.