Key points are not available for this paper at this time.
A route to the AB ring system of verrucarol is described. The successful scheme involved the formation of the A ring by a boron triacetate catalyzed Diels-Alder reaction. The second ring can be appended by an intramolecular Knoevenagel reaction to afford lactone 12b. This lactone could be converted into the desired keto alcohol 3b by reduction of the lactone and nitrile followed by an oxidation and Curtius degradation.
Kraus et al. (Sat,) studied this question.