Synthetic Approach Toward the Total Synthesis of Kempane Diterpenes via Transannular Diels−Alder Strategy
作者:Franck Caussanel、Keyan Wang、Sreekanth A. Ramachandran、Pierre Deslongchamps
DOI:10.1021/jo061230k
日期:2006.9.1
transannular Diels−Alder reaction (TADA) serving as the key step for the stereoselective formation of tricyclic [6.6.5] system 3. This synthetic approach also reveals that the geometry of the C3 group of such a tricyclic system plays an important role for the formation of the seven-membered kempane skeleton.
Sulfur helps! The first totalsynthesis of the title diterpene was accomplished starting from the Wieland–Miescher ketone. A diastereoselective sulfa-Michael addition enabled the generation of the delicate β,γ-unsaturated ketone moiety, while the tetracyclic kempane skeleton was readily constructed through domino metathesis.