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.