Unusual chlorinated pregnanes from the eastern Pacific octocoral Cavijoa multiflora

Two unique chloro-pregnane steroids have been isolated from the eastern Pacific octocoral Carijoa multiflora and their structures and stereochemistries were determined on the basis of spectral studies and molecular mechanics calculations. © 2003 Elsevier Ltd. All rights reserved. Pregnane steroids and their glycosides are rare in the marine environment and, ahhough the first pregnane derivatives were isolated from starfish,'"^ the richest sources of these types of compounds appear to be corals/ sponges/ and less frequently, echinoderms.'' In spite of the relatively few pregnane steroids isolated so far from marine invertebrates, several differing structural features deserve to be pointed out. For instance: (a) all pregnane derivatives from starfish possess a A^*"'nucleus simultaneously oxygenated at C-3, C-6, and C-20, (b) all pregnane steroids from sponges have a A^*^'-nucleus, (c) a 5a-pregnane nucleus with a vinyl side chain appears to be characteristic of corals. In pregnanes from sponges and terrestrial plants* the C-3 hydroxyl group is always ßoriented. However, in octocoral pregnanes the 3-OH may have indistinctly an aor ß-stereochemistry. In this work we report on the structure elucidation of two chloro-pregnane steroids 1 and 2 isolated from the eastern Pacific octocoral C. multiflora ( = Telesto