Absolute Configuration of the Cytotoxic Marine Alkaloid Monanchocidin A

The absolute configuration of the cytotoxic guanidine alkaloid monanchocidin A with 11 stereogenic centers from the marine sponge Monanchora pulchra was determined as 5R, 8S, 10S, 13R, 14S, 15R, 19R, 23R, 37S, 42S, 43R after extensive reductive degradation and conversion of the resulting alcohols to MTPA derivatives.