Structural Assignment of Tetrabromostyloguanidine: Does the Relative Configuration of the Palau'amines Need Revision?

摘要

The total synthesis of palau'amine and its congeners is currently a major topic in synthetic organic chemistry. So far, none of the research groups involved in the syntheses have managed to reach the complete structure of palau'amine. Herein, we present a new congener of palau'amine, tetrabromostyloguanidine (1; Scheme 1) which was isolated from the marine sponge Stylissa caribica. In contrast to the relative configuration of the palau'amine congeners that have been published, our studies on 1 have revealed a different relative configuration. Dibromopalau'amine (2 c) was also isolated from the same sponge.