Enantioselective total synthesis of (+)-tricycloclavulone.

The first total synthesis of (+)-tricycloclavulone having a unique tricyclo[5,3,0,01,4]decane skeleton and six chiral centers was achieved in a highly stereoselective manner. It includes a catalytic enantioselective [2+2]-cycloaddition reaction using novel chiral copper catalyst, extremely effecting an intramolecular ester transfer reaction, and asymmetric reduction of the carbonyl group on the alpha-chain using Noyori's chiral ruthenium catalyst.

New marine diterpenoids from the Okinawan soft coral Clavularia koellikeri.

Chemical investigation of the Okinawan soft coral Clavularia koellikeri resulted in the isolation of two new cembrane diterpenoids (1 and 2) and one new dollabelane diterpenoid, 3. Their structures were determined on the basis of the results of spectroscopic analysis. Compounds 1 and 3 were examined for in vitro growth-inhibition effects toward tumor cells.