Total Syntheses of (+)-Secosyrins 1 and 2 and (+)-Syributins 1 and 2

First total syntheses of (+)-secosyrins 1 and 2 and total syntheses of (+)-syributins 1 and 2 are described. The two chiral centers of diisopropyl tartrate were incorporated into target natural products. Stereoselective construction of the spiro skeleton of secosyrins could be realized by taking advantage of an alkyne−cobalt complex. The synthesis of these compounds established their relative and absolute stereochemistry unambiguously

Construction of the Benzylic Quaternary Carbon Center of Zoanthenol by Intramolecular Mizoroki−Heck Reaction of Enone

Stereocontrolled synthesis of the ABC ring framework of zoanthenol has been achieved. Our studies show that a β,β-disubstituted enone can act as a good acceptor of arylpalladium intermediates in the formation of a congested benzylic quaternary carbon center through an intramoleculer Mizoroki−Heck reaction. The cis B/C ring system was stereoselectively converted to the trans-fused framework through a SmI2-promoted deoxygenation of the α-hydroxy ketone