Prevezols A and B:: new brominated diterpenes from the red alga Laurencia obtusa

Two novel brominated diterpenes, prevezols A and B, have been isolated from the organic extract of the red alga Laurencia obtusa, collected from the coastal rocks of Preveza in the Ionean Sea, Greece. The structures of the new natural products, as well as their relative stereochemistry, were established by means of spectral data analysis, including 2D NMR experiments along with molecular calculations. (C) 2001 Elsevier Science Ltd. All rights reserved.