Unprecedented Elimination Reactions of Cyclic Aldols: A New Biosynthetic Pathway toward the Taiwaniaquinoid Skeleton

The acid treatment of 6,7-seco-abietane dialdehydes gives, in high yield, the corresponding derivatives with the 4a-methyltetrahydrofluorene skeleton of taiwaniaquinoids. A mechanism involving the elimination of formic acid from the cyclic aldol intermediate is proposed here. This process can be postulated as a new biogenetic pathway from abietane diterpenes to taiwaniaquinoids. Using this novel reaction, the first enantiospecific synthesis of bioactive natural cupresol and taxodal has been obtained.

Automated summary

The acid treatment of 6,7-seco-abietane dialdehydes leads to the synthesis of derivatives with the 4a-methyltetrahydrofluorene skeleton of taiwaniaquinoids in high yield. The proposed mechanism involves the elimination of formic acid from the cyclic aldol intermediate. This novel reaction enables the enantiospecific synthesis of bioactive natural cupresol and taxodal.