Oshimalides A and B, Sesterterpenes of the Manoalide Class from a Luffariella sp. Deep-Sea Marine Sponge: Application of Asymmetric Dihydroxylation in Structure Elucidation.

Oshimalides A (1) and B (2) were isolated from a Luffariella sp. marine sponge. The absolute configurations of the stereogenic centers in the cyclohexenone ring were determined by the modified Mosher's analysis of the reduction product. The absolute configuration of the stereogenic center in the dihydropyran ring was assigned by analysis of the 1H NMR data of the vicinal diols which were prepared by AD-mix reagents stereoselectively.