Total Synthesis of (+)-Allocyathin B2
journal contributionposted on 09.03.2005, 00:00 by Barry M. Trost, Li Dong, Gretchen M. Schroeder
The first enantioselective synthesis of (+)-allocyathin was achieved. The synthesis features a Pd-catalyzed asymmetric allylic alkylation to install the first quaternary center, a Ru-catalyzed diastereoselective cycloisomerization to construct the six-membered ring, and a diastereoselective hydroxylative Knoevenagel reaction to introduce the final hydroxyl group. The unusual olefin isomerization of the Ru-catalyzed cycloisomerization was discussed and exploited for the synthesis.